Comments by "GH1618" (@GH-oi2jf) on "The US electrical system is not 120V" video.

  1. I just looked up the voltage standard for Pacific Power in Oregon. it is 114/228 to 126/252 at the point of delivery. That agrees with your statement.
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  2. That just isn’t his subject here.
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  3. The United States and Canada have 120/240V split-phase service as described here, but we also have 3-phase sevice available for those who need it. Three-phase service would usually be 120/208V or 277/480V.
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  4. Exactly. I'm an old retired guy and I have never been shocked while handling a plug. I think I have been shocked only twice. Once as a young child sticking something in a receptacle. Once as a teen tinkering with electrical things. I had a device mounted on a board connected to power through two bolts put through the board. I reached behind it and put my wrist across the terminals (accidentally). The modern way to protect against shock is to have ground-fault circuit interrupters on every circuit with receptacles.
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  5. Not going to happen. Can you imagine the cost of changing the design of our electrical system? There is nothing wrong with it the way it is.
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  6. The hum is from that little transformer mounted on the side of the cabinet.
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  7. Our power outlets in kitchens typically are 20A circuits. To get more power you would need to install a 240V circuit, but few people have that in a residence. Commercial kitchens might have some 240V outlets. We just put a kettle on the stovetop to boil water.
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  8. We normally just assume RMS when discussing AC power. Peak to peak is for engineers.
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  9. Wrong. You pay for energy, not current.
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  10. No, you will not have double the current when you receive a shock from a 120V power line. The current will depend on the voltage and the residtance of the load (in this case, your body). The load will depend on what kind of shoes you are wearing, if any, what you are standing on, and whether you are holding on to something else with the other hand. All else being equal, the higher voltage will send more current through your body.
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  11. I woul guess the cntrol room had inadquate ventilation. Maybe the Plexiglas interfered with the ventilation.
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  12. will gates — Sixty cycles (Hz) was chosen by Westinghouse, who developed Tesla’s AC power system, after experimentation, as being the best balance of efficiency and practicality. Europeans adopted 50 Hz for no other reason than they thought 60 was too “American.” Using 100 was impractical, so they chose 50 Hz. There is no better example of the difference between American and European engineering.
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  13. New construction requires ground fault circuit interrupters. We don’t generally require old work to be upgraded merely because there are new codes.
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  14.  @shamrockshore6308 — Ok, but you are getting into details beyond the scooe of this presentation.
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  15. This example is not normal. He has a large breaker box. The main breaker comes with the box. The more slots, the bigger the main breaker. He may or may not get close to the capacity of the main breaker. Most houses will have a 100A to 150A breaker. I live in an apartment and have a 60A main breaker.
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  16. We do not use Imperial units in the United States. We use US Customary units and Metric units.
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  17. The distribution grid is 3-phase. Customers who need 3-phase power have a transformer which supplies it.
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  18. The bare wires are ground wires, which are as safe as the metal box containing the breakers and connections. He has removed the cover; normally, the box is covered and nothing is exposed.
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  19. If your receptacles are all switched, you wouldn’t ned a switch on a power strip. People who use power strips typically have a bunch of devices they want to turn off at the same time, so they need a switch somewhere. Some workbenches contain a row of receptacles and a switch.
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  20. I think a 240V induction hotplate would be useful, for heating water, but nothing else. Electric kettles are too specialized. They are for tea drinkers. You can just put an ordinary kettle on an induction heater, as long as it is induction-compatible. There are 240V microwaves, if you are into microwave cooking.
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  21.  @alazynoob7655  — Oh, I see what you mean.
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  22. Call it what you like, he is just explaining how it is configured.
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  23. No. Why would we do that? There is no advantage to be had in using 240V for common household devices. We have 240V available when we need it for high-power devices.
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  24. The US system also has 3 pin plugs, and the ground pin is also longer than the others. Not everything needs the ground pin, however, so 2 pin plugs are common. We also have receptacles with a shutter which opens only when a plug is inserted. They are required in some jurisdictions. I hate them. I bought some cheap ones to pass an inspection, then replaced with better ones without the shutter.
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  25. I’ve been in Europe a few times. I hate those plugs. Round pins? Harvey Hubbell tried round pins at first, but soon settled on the flat blades we (in North America) use today because they make a more reliable connection.
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  26. Moran Taylor — No, US is 240V single phase, with a center-tapped neutral.
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  27. We didn’t make mistakes. Our system has worked rather well for us for more than a century.
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  28. In the United States, most electrocutions happen when someone tries to work on an appliance without unplugging it. Next, they use an electric device in the bathtub, like a cell phone on the charger. Or they erect an aluminum ladder into electrical wires. Our plugs are not as dangerous as people think. The way to make them safer is to put ground fault interrupters on every circuit.
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  29. csongor végh — The US system has four wires: two hots (L1 and L2), neutral, and ground. An appliance that needed only 240V would get the operating voltage across L1 and L2 and would not need the neutral. If it had a metal chassis, that would be connected to ground.
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  30. Stephen Gerish — You are wrong. US households normally get only one phase from the 3-phase grid.
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  31. Color conventions are arbitrary. The US convention probably goes back to the very beginning of electrical service when all the wiring was black.
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  32. This fellow just likes having lots of circuits. His breaker box is not typical. But 240v circuits always have only one receptacle per breaker according to code.
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  33. pontymike56 — Browning has it right, except the substation, which delivers power to the final transformers, serves much more than a neighborhood. One substation can serve an entire small town, or a similarly sized section of a city.
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  34. Not the same. We do not have rings in our wiring.
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  35. Ni5ei — Those connectors are for high current fixed appliances, mainly dryers and ranges. They are hidden behind the appliance and rarely handled. A 15 or 20A 240V plug is much smaller and more convenient for tools and smaller appliances.
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  36. Saddutchman — He has a 200A main breaker because he wanted a load center with a lot of breaker positions. The main breaker just comes with the box.
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  37. We have 3-phase service available in the United States. It is used in commercial and industrial buildings.
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  38. Hans Wurst — The U. S. Customary system of measurement is a standard, it just isn’t your standard.
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  39. TmOnlineMapper — Ok, I’m imaging billions of 120V devices heading to landfills or recycling centers. I’m imagining companies that make motors and transformers unable to keep up with demand, and electricians planning to retire in luxury because of the insatiable demand for their services. I’m imagining homeowners trying to install 120v circuits in their homes so they can keep some of their favorite devices. I’m imagining people of modest means worrying about how they will pay for rewiring their home and replacing all of their appliances. In short, I’m imagining a disaster on an epic scale.
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  40. In the USA, we call that a Ground Fault Circuit Interrupter (GFCI). We can get circuit breakers with a GFCI built in. We can also get receptacles with the GFCI function, which are often found in bathrooms.
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  41. Akotski1338 — Sometimes the herd needs to be thinned.
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  42. He has a 200A main breaker because he has a breaker box with a large number of circuits, many more than is typical for a residence. It doesn’t mean he is using that much power. The box probably came with the main breaker already installed.
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  43. A transformer can produce whatever is wanted.
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  44. Meatbyproducts — I agree. I have made two trips to Europe recently. They are the worst.
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  45.  @paulobernay8040  — I have a graduate engineering degree and understand electricity very well. You are in no position to judge my knowledge of electric power. The point you raised to which I took exception was the current through a person’s body who receives a shock, not the current through a kettle. I don’t care how much current a kettle draws.
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  46. Usually two or three in a neighborhood of single-family homes.
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  47. J. A. G. — The importance of that incident is exaggerated. At any rate, how things might have been different is mete speculation. The United States has been involved in the development of metric standards for a long time, yet we still like our inches and feet.
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  48. Michał Pełka — We have them. What is your question, specifically?
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  49. Almost every receptacle in a modern US residence is grounded.
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  50. Marvin Heidenstedt — We have a 3-phase distribution system, but most households get just one phase, derived from two of the distribution grid phases. We can get 208Y/120V for residential use, but higher voltages are for commercial or industrial use.
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  51. The AC system used in North America was designed by Westinghouse, not Edison.
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  52. Rob Marrin — I doubt it. In my long life, I’ve never seen or heard of someone doing that. Every time you bought some small appliance, like a coffeepot, you would have to change it. You would have to order all your parts from the UK. If you did that to your phone charger, it wouldn’t work in an airport, so you would have to carry an adapter with you for domestic flights. Whether you owned or rented, you would have to change all the outlets back when you moved. It’s a truly loony idea.
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  53. Your figures are off. RMS for a sine wave is 70.7% of peak, so 169 peak volts gives 120V RMS. The 240V RMS that we use in the United states is twice the 120V RMS, so 338V peak. We commonly just use RMS values without stating “RMS” explicitly.
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  54. For a single 240v circuit, I expect. I have two 120v circuits which have the switch handles tied together. They were installed by an electrician and inspected. He had a reason for doing it having fo do with Ground Fault detection.
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  55. Only pedants argue about this. There are two ways of looking at it, and they are equivalent.
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  56. runforitman — I don’t recommend testing this hypothesis.
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  57. It is incorrect to think of the neutral as carrying the current back to the source. AC current flows both directions. The correct view is to think of the 3-wire system as having two 120v circuits comprising one hot wire and the neutral each, in opposite phase. The shared neutral carries the difference of the current for 120v circuits. A 240v circuit uses just the hot wires, which add to make 240v because they are in opposite phase. Any circuit only needs two wires, so the neutral is unnecessary.
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  58. In North America we have a lot of trees that are suitable for power poles. They are relatively inexpensive, naturally nonconductive, and can be climbed by linemen using simple equipment. We also distribute power underground in places, but it is far more expensive to do it that way.
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  59. SpaceBuckaroo — I hate those. I got some cheap tamper-proof outlets for my recent kitchen work because my electrician said I needed them for code, then replaced them with Eagles after I passed inspection.
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  60. Mar Tijn — Few American homes use that much power. Sometimes we just like plenty of headroom in the main breaker. Having lots of breaker slots is what one often wants, and a larger breaker box might come with a large main breaker already installed.
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  61. James 4theDoctor — These are the 3-phase options from my power company. Getting 480V is just a matter of using the appropriate transformer. The distribution voltage is much higher than that. 240/120, 4-wire 240, 3-wire* 208Y/120, 4-wire 480/3-wire** 480/277, 4-wire 480Y/277, 4-wire
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  62. A 240v circuit in the US is single-phase. You only need two wires for 240v, but if a 240v appliance also has 120v components, then a third wire is needed for the neutral. The fourth wire is for ground.
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  63. Marshall Dudley — This is a muddled description.
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  64. We always use RMS when referring to AC voltage, implicitly.
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  65. Antonio Fdez — Oh, you wouldn’t want to do that. You could get a very nasty shock from a floating system. Holding the neutral at ground gives you a defined voltage to ground.
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  66. Correction: They would have to compare the neutral current with the difference of the two hot lines.
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  67. Dima Golovin — That would be trivial. The differences are 20, 15, and 35.
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  68. fluffigverbimmelt — I scoff from my kitchen with a professional gas range.
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  69. crapcbm — In the US, the common 240V service for households is single phase. It is split to get two 120V sides.
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  70. Nominal service voltage is 120V +-5%. Utilization voltage can be a little lower because of voltage drops in the customer wiring. It doesn’t matter whether you call it 110, 115, or 120, it’s all the same thing.
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  71. Do you mean the pilot light? Normal.
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  72. Exposed wires? Normally, there is a cover on the box.
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  73. Tea Extra Hot Please — Edison was being practical. He was just trying to build a practical lighting system. He was a jerk, but that came later.
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  74. Luka Marinov — A circuit is whatever you put on one breaker. That’s how we commonly use the term, anyway. We have underground power wherever people want it and are willing to pay for it. It isn’t cheap. Tall, straight trees for poles are plentiful in the US.
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  75. basil katakuzinos — Isn’t an RCD the same thing as what we call a GFCI in the US?
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  76. For lighting, and 480v 3-phase for the elevator motors.
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  77. The bare copper wires are grounds.
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  78. He did it using DC, though.
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  79. Most likely you did not get a bad shock only because you did not provide a good path to ground. Touching one hot wire can be very dangerous, possibly fatal, if you have a good contact with ground.
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  80. Mr Glide — I’ll add that if you want to standardize something important, get the British and most of their Commonwealth to drive on the right.
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  81. We (in the USA) have devices that detect ground faults by comparing currents. The best way to install these is in the circuit breaker. Any new work should be using these.
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  82. Matej matej — From an American viewpoint, it is, although as of late the distinction has become much clearer.
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  83. David Sheik — It doesn’t have to be pretty to be safe, just wired properly and securely. There is a cover except when working on it.
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  84. The power of a circuit is nearly all dissipated in the device, not in the wire bringing power to the device. Consider a simple resistive heating element. The resistance of the heating element must be low enough to allow a significant current to flow, but will still be much higher than the copper wiring. The voltage drop in the circuit is proportional to the resistance of the various parts of the circuit, so that will be greatest across the heating element. The current is the same everywhere and the power is the product of the current and the voltage drop. The power loss in the wire therefore should be small. But if the circuit wires are too small, their resistance wll be proportionally higher, the voltage drop will be higher, and the power dissipation will therefore be higher. The power is what heats up the heating element and the wires. You don’t want the wires to get hot. You control that by increasing the diameter, thus lowering the resistance, thereby lowering the voltage drop and the power dissipated in the wires.
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  85. Except that 480/277V would be a three-phase service.
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  86. Eddhick — The voltage is commonplace, but typically it is used in only a few applications: resistance heating, water heaters, ranges (cooking), clothes dryers. Small appliances and power tools are almost always 120V.
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  87. It also affects the efficiency and size of transformers.
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  88. We do have GFCIs, but they are only required on new work. Therefore, we have a lot of unprotected circuits in older houses.
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  89. Having only 120V in a kitchen is a limitation in that regard. Our 120V induction plates are only 1800 Watts, which isn’t that much if you have to boil a large pot of water. I would like to have one 240V kitchen outlet for a commercial induction plate, but I’m not sure what the electric code says about that. I know the manufacturer of a leading 240V induction plate says it is not for residential use.
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  90. Pavel Peřina — It was probably a cheap outlet device, or worn out. You should have reported it to the hotel.
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  91. Dennis S — Some people do not like that term. It is 3-wire 240/120V.
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  92. If one phase of a 3-phase system is 230V to neutral, phase to phase is 400V.
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  93. Laddie — You need headroom. You don’t want your average current to be too near the breaker limit or surges will be tripping the breaker. Another factor is that there are usually at least two duplex receptacles on one kitchen circuit. You might be running your inducion heater at max to boil water, then somebody wants to toast a bagel.
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  94. phorzer32 — Or, you could just calculate it.
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  95. Correct me if I’m wrong, but I don’t thing Europeans are allowed to work on their own electrical systems. Is that right? In the USA, a homeowner may do his own wiring, subject to permits and inspections. That’s one reason lower voltage is advisable. But the main reason for lower voltage is just historical.
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  96. I don’t know to which country you refer. In the USA, the plugs for 240V are entirely different from those for 120V. There are a few different plugs for each voltage. They differ based on the current demand. We do have circuit protection (we call them ground fault interrupters), but existing circuits don’t have to be upgraded to have them.
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  97. When I travel back in time, we were destroying German infrastructure from one end of Europe to the other.
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  98. John DoDo Doe — You are right about arc lamps, but they didn’t last long. The original Edison DC system in New York City used 110V for his incandescent lamps and for two arc lamps in series. Everything developed from that, in particular our (in the US) 3-wire system.
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  99. I don’t believe that. Urban myth stuff, unless you have a citation from a respected scientific journal.
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  100. I’m pretty old, and I have never been shocked while making or breaking a connction with a US plug. I’ve never heard of it happenning. If it did happen, it would be survivable.
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  101. 1) Why? several reasons: Because we only have to install a GFCI for new work. We rarely work on the main breaker. We add a circuit and add a GFCI breaker for that circuit. Because when GFCIs came in, we only had to have them on outlet circuits near water, in the bathroom and kitchen. They were usually provided with a combo receptacle/GFCI. Some houses don’t even have a main breaker. It used to be that if you could turn off everything with six switches, you didn’t have to have a main breaker. I don’t know if the current rule is different.
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  102. Lewis Templeman — It is mostly old, poorly maintained wiring that is unsafe. We do have a lot of that. Low usage of GFCI breakers also detracts from safety. But a new installation of a North American system, installed correctly by a licensed electrician, with AFCI/GFCI breakers on every circuit, is as safe as any other system. The basic design of the system is not unsafe. When people are injured or killed by electricity, it is almost always due to their own negligence, not to a fundamental design weakness in the system.
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  103. jazwiec — We would be if it were a race to the highest voltage. It isn’t. We have high voltage where we need it.
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  104. Fahrenheit38 — No. Most electrocutions have nothing to do with the plug. A common one is using a metal ladder near power wires. There’s a good argument for undergrounding.
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  105. It is possible to get 277/480V 3-phase service, but not everywhere. You would also need 120/240. Generally, 3-phase service would be available in commercial areas.
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  106. christopher huff — The most common cause of non-work related electrocutions in the United States is from people trying to repair their appliances, according to the Consumer Product Safety Commission.
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  107. Murlock2000 — No. Hot wires are black. Neutral is white. Ground is green or bare. Sometimes red is used for unusual applications.
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  108. Gustav Streicher — If that’s the case, your household wiring also has reactance.
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  109. Ground is the same everywhere. If there are three pins on the connector, one of them is ground.
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  110. Charles — When the panel is closed, it is all metal. There is no way for a mouse to get in.
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  111. Basil Kearsley — The US and Canada use 60 Hz because that was determined to be the best compromise of performance, efficiency and practicality when the Westinghouse system was developed. If the frequency is too low, some lamps will give unsteady light. Higher frequencies also mean more efficient transformers, but too high a frequency has consequences for the dynamos. Sixty cycles just worked out to be the optimal compromise.
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  112. Travis — You wouldn’t want to connect two grids with unsynchronized frequencies.
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  113. horaxtax — Some have green insulation, but in a cable the grounding wire is usually bare.
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  114. That's a shocking admission. I started working with electricity about 65 years ago and have only been shocked by line voltage twice that I can remember.
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  115. I would not want to test that assertion. I have been shocked by 120VAC only a couple of times, and that is enough.
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  116. Douglas A — I don’t think we are. You would have to do a detailed analysis to answer that question. To start, what is the diameter of copper conductor used for the most common household circuit in Europe?
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  117. Electric chairs have not been used in a long time.
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  118.  @TheDutchGuyOnYT — There are five states that still have it. The last execution by electric chair that I remember was of Ted Bundy, a serial killer. He deserved it. I think it is the most barbaric of modern methods, myself. Edit: The last seems to have been in 2018 in Tennessee. I didn’t know that it was used that recently. It should be abolished. I am not opposed to all death sentences, however.
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  119. His subject here is 120/240v split phase, which is particular to N. America.
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  120. MrFreddyFudpucker — It is not earth return. The wire near the base of the transformer is the neutral.
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  121. RMS is implied when we are discussing AC.
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  122. Sarah Court — Part of the reason for them is that arcing current on disconnect from a 240V line can damage the socket. We don’t have that problem with 120V. As old as I am, I’ve never seen or heard of this happening with our receptacles. It’s just a cost issue in my opinion, not a safety issue. Any safety issue has been addressed by tamper-proof receptacles, and by ground fault interrupters. A switch doesn’t provide much protection, because almost any child can throw a switch. We (in the USA) have a simple, reliable power receptacle. There is no need to mess with it. Anybody who wants a switched outlet can get one easily by replacing a duplex receptacle with a singl and and a switch.
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  123. You are wrong. This is is a very basic subject. You need to go back to the beginning to learn practical electricity.
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  124. checkwegg — The bare wire is ground.
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  125. mikael Lolpi — Sure. You can get 208/120V 3-phase in the US.
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  126. AsiAzzy — I think you have some mistakes here. Residential grade 3-phase is 208Y/120V. I don’t know why you think you would have trouble welding in the USA. We do welding here. Whatever welder you have, you just need to get a suitable electrical service.
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  127. Jelle Smits — The meter shows energy, not power. Energy is power integrated over time. There is usually one meter per household, located near the circuit breaker box wher the power lines come in. Remote reading of meters is a technology which is independent of the thing being metered. Where I live, we have that on our natural gas meters.
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  128. When I (in the USA) was young and reckless I made a hot dog (frankfurter) cooker by putting two nails through a board, connecting a line cord, impaling a frankfurter, and plugging it in. This device was not UL approved. I wonder how that would work at 230V — it might explode, I think. For the curious, it did cook the frank, but there was a flaw. The ends beyond the nails didn’t get cooked.
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  129. Sampull MC — We do not use Imperial units in the United States. Our common units are U. S. Customary units, which predate Imperial and differ in some respects.
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  130. In my long life I have never received a shock while inserting or removing a US electrical plug. I do not think there is anything wrong with them. The modern way to make them safer is to use ground fault circuit breakers on all outlet circuits.
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  131. The main breaker probably came preinstalled in the panel. He probably chose a large panel because he wanted a lot of breakers. It is more convenient to have more circuits with fewer devices on each when you have turn off a circuit. He might never be using half the capacity of his panel.
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  132.  @groh — The power company decides what wire to use for the service drop, based on evaluation of the customer's needs. It isn't likely the wire would be damaged before the breaker would trip. A 200A main breaker is not unusual in the USA.
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  133. When referring to AC power, we use RMS voltage, which is a type of average. If the supply is stable, and the loads are constant, the RMS voltage at the customer will be stable. When the RMS voltage fluctuates, it is due to changes in the loads or in the supply.
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  134. Lord Garth — We have underground power wherever the propery owners are willing to pay for it. We don’t coerce our citizens to pay for something they don’t need, at least on that subject. There may be another factor in play also. There was so much destruction in European cities during WW II that major reconstruction was required. I’m guessing that a lot of the undergrounding of the power grid was done at that time.
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  135. true
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  136. Manuel — I’ll bet a lot of underground wiring in Europe was paid for under the Marshall Plan. You’re welcome. We do have underground wiring where people are willing to pay for it. We don’t generally force it on the property owners. My hometown recently refurbished the main street through town to include underground wiring along with other improvements. I’m guessing the cost was distributed over the whole town. Normally, undergrounding would be paid for by the property owners directly affected.
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  137. People with electric cars install a 240v charging circuit. Charging on a 120v outlet is slow.
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  138. stinchjack — The 208V is just an artifact of producing 3-phase with 120V legs. That would be a practical way to modernize the North American electrical system. We have that service available now, but we don’t have many devices designed for 208V. Mostly motors. You might get that service if you had a shop with a lot of motors. I wonder what happens if a dual voltage 120/240V device is plugged into 208V.
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  139. Normally in the US there will be 240V outlets only for a clothes dryer and an electric range. Those are in hard-to-reach places and use a cumbersome plug which is intended to stay plugged in indefinitely. For portable devices a different, smaller plug is used. You would have to have a circuit installed in your kitchen to get that. I have never seen a residential kitchen equipped with one. If I added a 240V outlet to a kitchen, it would be for a commercial induction unit so I could boil water for any purpose. I don’t see the advantage of an electric kettle. For just boiling enough water for tea, a common 1800 watt 120V induction unit should suffice.
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  140. What about it? Our transmission and distribution systems are 3-phase. Commercial and industrial customers often have 3-phase power. Residential customers usually have single split phase power.
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  141.  @williamschnl — The three phase system is the same, in principle, everywhere, but the voltages will differ. In the United States the voltage will usually be either 208/120 or 480/277.
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  142. dave miller — And 60 Hz is more efficient than 50 Hz.
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  143. He’s not forgetting anything. This video just isn’t about your system.
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  144. Alays use a Tripp Lite Isobar with your computer. Or switch off the power during a storm.
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  145. feeldennis — North American system is single phase with a center-tapped neutral. But conceptually you could think of it as 2-phase with a 180° phase angle. They are equivalent.
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  146. They work for us. The voltage is relatively safe. The connectors are compact and inexpensive.
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  147. But it isn’t twice the “cable” size, in practice. I looked up typical wiring for the UK system and it appeared to me they used wires as large as those in the US. That assertion requires documentation.
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  148. Why what?
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  149. We can put a switch on any receptacle. We usually do it only for one which will be used for a lamp. If we thought it was generally useful, we would have them.
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  150. DJAlup — The US has 480Y/277V 3-phase. It is a commercial service. You can’t put it in your home.
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  151. Derpu Wolf — The neutral is a current-carrying wire at ground potential.
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  152. A homeowner can do such work without being licensed, but a permit is required and the work must be inspected and approved.
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  153. It is not “standard.” It is the largest breaker typically seen in a residence. A main breaker of 100 or 150 is more common.
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  154. Engy Wuck — The only thing compatible with the Edison DC system is the 120V base voltage and the screw base on an Edison lamp.
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  155. Kevin Brammer — Does that mean “fault interrupter”? Sure we do.
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  156. Andreas Kuhn — I learned E = IR. What happened to that?
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  157. Harrick V Harrick — Most people only have to touch those pins a couple of times before learning not to do that.
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  158. Robert Cartier — It is also related to the voltage difference. A 240V connection does require more protection.
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  159. Why?
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  160. Julius Eskola — Yes, if you give two phases to a customer, and it is 400V across the phases, that would be 400V service. But you could give only one phase to a customer, then it would be 230V.
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  161. Obsolete.
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  162.  @joekirklin  — Maybe, but it isn’t used much anymore, at least not on farms.
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  163. Strothy2 — We would have the power company provide it and have an electrician install it.
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  164. antagonist9000 — Two-phase would just be two phases of a three-phase scheme. Do you mean split-phase? That is a single phase, not two-phase.
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  165. Wes Johnston — Not much to that. Westinghouse determine that it was the optimal compromise. It more efficient in transformers and transmission lines than lower frequencies, but practical problems arise with generating higher frequencies.
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  166. Westinghouse developed our AC electrical grid.
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  167. Glenn Chartrand — I’ve never heard of that. I won’t believe it without an authoritative reference.
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  168. security camera — A load center with a 200A main would not allow you to use all that capacity through one breaker circuit. A level 2 (240V) charger is about 10-12 kW.
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  169. Marco Pöhler — You haven’t stated what material you think is not safe. I assure you, we have codes which govern the design of electrical panels, and their use. Square D is a top brand, but I won’t vouch for how it has been used here.
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  170. Very Interested — It’s 170v peak.
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  171. It is pointless to argue about what to call it. Call it whatever you like. What is important is to understand how it works and the presenter here has done a good job of explaining that.
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  172.  @jonathonshanecrawford1840  — It is actually the other way around. We derive 120V 2-phase from a single-phase 240V supply by using a center tap on the secondary of the transformer.
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  173.  @jonathonshanecrawford1840  — Saying that “it’s the current that kills” is simplistic. In any case, for a given resistance, say the resistance of your body between a hot wire and ground, the current is proportional to the voltage.
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  174. Are you referring to the main breaker in his panel? Electrical service panels often come with a main breaker installed by thr manufacturer. This is an usually large panel for residential use. It contains a 200 Amp breaker simply because of the number of breaker positions in the panel. If it were used in an industrial application, it could easily need a 200 Watt main.
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  175. I doubt it is more expensive, all things considered.
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  176. What do you mean "just sits in a box"? Do you mean they are not connected to a circuit? The pin between the toggles just makes them work together as a double pole breaker.
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  177. It is for transmission and for large motors, but it is not necessary for all the little electrical things found in a residence. If you have a shop with a lot of stationary power tools, you can get three phase in the US if you want it.
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  178. We use 3-phase in the USA also, just not usually in residences.
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  179. It isn’t a competition. He is metely explaining how US electric service works.
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  180. GBiv78 — In the United States we use U. S. Customary units, not Imperial.
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  181. The exposed copper is ground.
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  182. x9x9x9x9x9 — baloney
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  183. Ground fault circuit breakers are the modern solution.
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  184. Habit. Even electricians do that.
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  185. 415 is 240 times the square root of 3.
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  186. scott web — That depends on your intended result.
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  187. Jonathan Rabe — Phase out 120v? Who? The USA? We have billions of 120v devices! You want us to throw them all out and rewire our houses? In phases? How would that work?
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  188. Alexander Zamani — The bare wires are grounds and the panel is closed unless being worked on.
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  189. His panel probably has much more capacity than he actually needs.
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  190. The best way to install leakage current switches in the North American system is to use circuit breakers which contain the function. What is your objection to a snap-in breaker? They hold tightly. I’ve never heard of a problem with the breaker connection to the bus bar.
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  191. John Davies — In the US, a household has two 120V phases in opposite phase. We have 240V between the hot wires of the two phases.
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  192. metalliferous1 — It would be better if we had 208/120V 3-phase everywhere. Then it wouldn’t seem weird.
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  193. We have three phase power and three phase motors, where needed. They are not needed for residential appliances. Despite our "Neanderthal" technology, we (in the United States) were the dominant industrial power in the world during the 20th century. We are not dominant today, but not because of our electrical power system.
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  194. Yes, the voltage is 120 or 240 V RMS, but the "RMS" is usually implied. It isn't necessary to keep restating it.
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  195. Eric Tay — Calling “gasoline” “petrol” is a little strange as well. It is derived from petroleum, but it isn’t petroleum.
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  196. Mike Flynn — He certainly can.
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  197. David James — The catch is that rooms get reused. Children grow up quickly and people change rooms or move. It would be a nuisance keeping up. My view is that parents have a duty to child-proof their homes as needed.
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  198. There is no need for 3-phase power in a residence, but you can get it.
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  199. ESSBrew — I have a brand-new pair of ganged breakers. My electrician used that for some obscure reason.
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  200. EIEIOlsen Studios — I don’t advise paying off an electrician. The way to do it would be to put a US plug on the kettle. But your problem is, you don’t have a 240V receptacle in your kitchen except possibly for a range, and that’s the wrong one in the wrong place. An electrician might be able to put a 20A 240V receptacle in the kitchen if the codes allow it. In my dream kitchen I would have one such outlet for a commercial induction unit, then I would boil water in any compatible vessel.
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  201. Epsilonsama — It isn’t voltage that distinguishes 3-phase power. You can have a y voltage in single-phase or multi-phase. The advantage of 3-phase power is that a simple motor design will self-start in the proper direction.
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  202. Ralph Little — No, the frequency is what it is, regardless.
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  203. Ralph Little — If you look at the waveform across any two legs of a 120° 3-phase system, it is sinusoidal.
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  204. john van kampen — That makes sense.
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  205. Few residences in the USA have 3-phase. That is a different subject.
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  206. J D — But in countries with 240V or more to ground, they take extra precautions which we don’t. The recessed outlets are a simple example of that.
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  207. Richard McGee — Good point. Everybody is familiar with household service, of course, but the commercial sector is a huge part of the picture.
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  208. SH66 LARS — US 240V is not “phase shifted.”
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  209. Jan B. — The neutral wire is different from the ground wire, even though the neutral is grounded at the panel.
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  210. I think that’s an urban legend with little basis in fact, if any.
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  211. You are mixing up power, current, and voltage and not making a coherent argument. The pincipal advantage of 3-phase over single phase is that less copper is required to transmit a given power. That is also true for voltage: higher voltage means lower current, hence less copper for a given power. These two reaons are why power transmission is done with 3-phase (delta) high-voltage everywhere. When power is delivered to a residential customer, it is not so simple. Most electric devices in a residence, lighting and electronics, are inherently single-phase. Motors designed for 3-phase are simpler and more efficient n the use of materials, but this is only important for large motors. Residences don’t have large motors running most of the time, so a 3-phase supply would not usually have a well-balanced load, which would be needed for maximum efficiency. In the USA, the power company balances the load by distributing 3-phase power, but feeding residences with one of the three phases, using all three phases to serve a nighborhood. We also use 3-phase poer for commercial buildings and multiple unit residential buildings. In a large commercial building the lighting (all of which is on at once, usually) will be distributed among the phases. Large motors, such as for elevators and air conditioning, will be 3-phase. In an apartment builing, living units will be distributed mong the phases. Common equipment fo elevatrs and ventilation will use 3-phase motors. That way you get the balance needed for efficient use of a 3-phase transformer. It is not true that the single phase transformer that we use to deliver power to one (or a few) single residences is inefficient. It’s a complicated problem. You can’t get the answer with hand-waving arguments, or by considering just small pieces of the system. You would have to compare the two systems for a small town, at least, because the distribution systems are different. You would have to take into account all of the components of the distribution system and the end use. It isn’t worth the trouble, though, because the power companies worked out their respective systems long ago and they aren’t going to change them. They both work well for their intended purpose.
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  212. Devices generally have switches. Only low power devices, like cell phone chargers, lack switches. That little spark is harmless when the power is low.
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  213. gadjetsvideo — In the USA, up is on, by convention. But if you have two switches controlling one light, you have to break the convention. In that case, the light should be on when one switch is up and the other is down.
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  214. We use single-phase 120v motors in residences, mostly. I just counted eight motors in my apartment, not counting small tools and appliances like a mixer and a drill. They all work perfectly well. Someone with a large power tool such as a table saw might have a 240v single-phase motor, but it could be 120v. Only someone with a shop containing several power tools would be likely to consider getting 3-phase service. In that case it would probably be 120/208 3-phase. Industrial customers would be the most likely to have higher power 3-phase service.
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  215. I have never heard of accidentaly getting the wrong voltage. I have never heard of someone being electrocuted on a 120V circuit, although it is possible if well grounded. Most electrocutions inside the home happen when people try to work on an appliance without unplugging it first. Or trying to do their own wiring and being careless. Outside the home, using an aluminum ladder near power lines is a favorite way to electrocute yourself.
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  216. I’ve been there and used those plugs. I don’t get the round pins on the plugs. The first plugs in the US had round pins also, but they were soon changed to flat blades.
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  217. EP1CMINER — It’s the same thing. We try to maintaing 120V.
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  218. MalteseOwl — That’s not the reason.
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  219. A typical Level 2 (240v) charging station that we would put in our home would be up to 50A on a single phase. That’s 12KW. To get more power you would probably need to get special service from the power company. You can’t get multiple phases from single phase service with a transformer.
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  220. I don’t understand your use of “awkward.” We flip a switch and the light comes on, just like anywhere else. I’ve used European plugs. I plug something in and it works. There is no important difference. The plug and the voltage must be compatible, otherwise it is the same to a user.
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  221. Conspiracy Caves — Rural electrification started in the 1930s. I expect a lot of remote places have 240V by now. Besides, you only need three wires to run 3-phase Delta.
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  222. Martin Houlton — Your higher voltage requires use of more secure receptacles. Current US standards require ground fault protection on outlets, which suffices.
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  223. The switches are on the devices. We don't unplug a lamp to turn it off. There are some common devices without switches. A charger for a cell phone has no switch. We unplug it, but we don't leave it on the floor. Why would anyone do that?
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  224. When engineers get it right the first time, there is no need to keep tinkering with it,
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  225. John Meredith — There is no question that safety devices are the key to making any electrical system safer. We have them, but they are only required on new work. We have a lot of old work in the US.
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  226. sapphirepilot — Which power leads do you think waste copper?
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  227. Witgang Younotube — In the US, a pole-mounted transformer might serve up to four customers. It depends on the layout. The power company will use a transformer which is sufficient for the particular requirements.
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  228. 2009mechanic — Transformers are generally sized for typical loads. A customer who has greater than usual loads should discuss it with the power company beforehand.
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  229. Cees Borger — Not really. You have polyphase service with 230V legs. In the US, we have 120V legs. In most jurisdictions, there cannot be more than 150V to ground in a dwelling, except for a permanently wired device.
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  230. Blanchy10 — 12, 24, etc. are decimal numbers, just not multiples of ten. The base system is arbitrary. We happen to use base ten. It does not follow that 100V would be the optimal value for operating your lights. It turned out to be 120/240 because the engineers who developed it weren’t French, they were practical people.
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  231. You could have a 240v receptacle for a 240v device.
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  232. Daniel Louw — It doesn’t matter if one side of the split phase carries more current. That just means there will be current flowing in the neutral at the supply.
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  233. Everybody who understands electricity knows that whether you use "110" or "115" or "117" or "120," it is all the same thing. It is a trivial thing to let annoy you.
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  234. It is nothing to quibble about. We know how the North Americam electric service works. We know how European 3-phase service works. It is what it is, whatever you call it.
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  235. That is a reasonable way to look at it, but even so, I think quibbling about what to call it is pointless. It is better just to understand how various systems work, without judgment. We, in North America, have the voltages and the power to do what we need to do. I expect the same is true of Europe.
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  236. We have a lot of trees for poles, so it is practical. The pole is an insulator. It can be climbed by linemen with simple equipment. Of course we also have steel towers for transmission lines and we can put distribution lines and transformers underground. It is just a matter of cost. Undergrounding is expensive so it isn’t done everywhere.
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  237. SuperRecordman — I don’t get this “flimsy” complaint. I have never in my long life broken a prong on a US-style plug. The flat prongs made good contact with the mating surface inside the receptacle, and the plug is held in place securely. Those are the main things you need in a plug.
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  238. Transmission is done t high voltage everywhere.
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  239. You are the reason we have to have tamper proof receptacles nowadays.
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  240. Lyks Zyxer — I’ve never touched the prongs while inserting or removing a US plug in my long life. Why would anyone do that?
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  241. Bailey Harrison — Induction motors don’t need brushes.
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  242. Honest Troll — Right.
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  243. stampy Dragon — No, there is no phase shift.
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  244. It does not. Energy is the measure of usage of electricity, not voltage.
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  245. Don’t believe everything you are told. In either case, be careful when working with electric wiring.
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  246. l00k4tstuff — Wrong.
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  247. Danielle — That’s baloney. Where did you get that?
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  248. It isn’t important. For example, I have looked at specifications for motors which can be configured for either 120V or 240V. The spec says that it doesn’t matter. We use 240V when we need higher power, such as for heating elements, because the current would otherwise be too high. Our 120V circuits are generally limited to 20A. If you want better efficiency, turn off lights when you don’t need them.
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  249. It isn’t a contest. We have 3-phase service with higher voltage as well, typically 480/277, but not for residential use.
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  250. In the US, a modern residence usually has an upper limit of 48,000 Watts of power available. That is more than enough for almost everybody. People who need more power for some reason can get a special service with more power.
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  251. What the heck is “2.5 phase”? Three phase power is available for those who need it.
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  252. Soylent Green — Where I live, 3-phase service is 208Y/120 or 480Y/277. My building is mixed service, with 208Y for the heavy-duty motors and 240 split phase for the residential units.
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  253. Paul Standaert — Old school, because now there is a probe which can sense the voltage through the insulation, and by only touching one wire.
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  254. Markus Quatember — The Ground Fault Circuit Interrupters are either built into the breaker for a single circuit, or combined with a receptacle on the circuit. The energy meter is usually on the outside of a house near the panel.
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  255. jochum334 — What would you use?
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  256. Probably he does not use close to 200A. That is the maximum size breaker normally used in residences. The main breaker comes preinstalled in breaker panels. He got a large panel because he wanted lots of circuits, and the large panels come with large breakers.
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  257. Rhian Taylor — The fatality rate is not due to either the voltage or to the frequency. That is simplistic thinking.
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  258. It is more efficient in one respect to bring the medium-voltage distribution lines close the point of service, to keep the low-voltage service lines shorter. Everything is a tradeoff, though. You would have to look at the entire distribution system for a small city in all of its characteristics to get a meaningful comparison. The North American electrical distribution system works well, it is just different.
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  259. Alvin Yugika — That’s a little misleading. The modern nits are defined in terms of metric units, just to avoid the redundancy of having two separate standards. The origin and philosophy are totally independent.
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  260. Cory Swanson — In the US, we need three-phase service to get 208V.
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  261. I don't know about "most." For small apartment buildings with only one or two stories, that may be so, but buildings tall enough to need an elevator are likely to have three-phase. My building has only 40 units but four stories. We have three-phase for our elevator, but the individual units get a single phase 120v. I'm not sure if we have 240 or 208, because I don't use that circuit and have never measured it.
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  262. Kevin Derr — 400 Hz is easier to filter to get nice, quiet DC. I used to use computer systems that were powered from 400 Hz motor-generators for that reason.
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  263. We (in the USA) use whatever we need. Power customers who need higher voltage 3-phase can get 480/277. Nobody needs 400 volts in a residence.
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  264. I learned it as E = IR. It doesn’t matter.
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  265. zlac — That’s baloney. It’s rationalization for using a less efficient frequency.
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  266. I don't believe what people say about 60 Hz; nobody ever gives a citation. As for RCDs, we have Ground Fault Circuit Interrupters in North America, which is another name for the same thing.
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  267. Derek O'Smith J. — People with electric cars usually have 240V chargers installed. It is possible to get more.
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  268. Jason Reynolds — What’s wrong with a bare earth? The breaker box is metal, after all. Just a little paint separating you from the electrical ground.
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  269. I have no dryer, a benefit of living in a low humidity climate. Much cheaper than either dryer type.
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  270. Projects Forever — You would run into other problems.
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  271. Tom Joad — It is not.
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  272. Loading Official — The panel is grounded.
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  273. Most likely, he never gets close to the capacity of the main breaker. He has a large panel, probably because he wants lots of circuits. A large panel will come with 200A breaker pre-installed.
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  274. David Dunmore — What is the OS Code?
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  275. Jason Slagle — It varies, but 2300V and up.
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  276. Your 400V is less than 460V (twice 230V). It’s the same principle.
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  277.  @mathaithomas3642  — You are only allowed one device on a 240v circuit.
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  278. Bobby Winters — We settled on 60 Hz very soon after we invented AC power, because it gave the best balance of efficiency and practicality. The transformers are more efficient and the light from early incandescent bulbs was more uniform. A higher frequency than that would run into practical problems for generation. It just worked out. Europe uses 50 Hz because they think the numeral “6” is the mark of the devil, and no other reason.
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  279. William Smith — You need to replace your outlet. Get a better grade.
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  280. Nobody who works with lumber expects it to be. That’s called a “nominal size.”
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  281. We do have Ground Fault Circuit Interrupters, but it doesn’t look like he has any GFCI breakers here.
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  282. This isn’t about European electrical systems, so of course that is “missing.”
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  283. I looked up motor specs awhile back and the manufacturer said there was no difference in efficiency whether you hooked it up for 120v or 240v. That’s for small motors. At 240v the current draw will be lower and there is some advantage to that. Large motors might be three phase and there are advantages to that.
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  284. Jeremy Andrews — It is very easy to put a switch and outlet combo in place of a duplex outlet. Anybody who wants one can have one.
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  285. Brian B — Two hot wires in a household circuit in the US is single phase.
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  286. It would be better to add a 240V circuit. The 30A plug for a dryer is too cumbersome for light duty use, and it would be unnecessary risk to be swapping plugs frequently. That plug is designed for semipermanent use. Your drier generally stays plugged in until you repair or replace it. You should always turn off the circuit at the panel before inserting or removing the plug.
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  287. Teun Noordkamp — We (in the US) can put leakage detectors in our breaker boxes. We call them GFCI breakers. A GFCI can also be installed on a circuit as part of an outlet.
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  288. Why do you care? I just want my coffee maker to work, and it works well on 120v.
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  289. You would use a 240 V GFCI breaker.
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  290. TimDVProjects — “Electrocution” is fatal by definition.
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  291. Plp Hrmon — If the panel is only 40 years old and does not have a main breaker, then I’m guessing it has a small number of circuits. Is that right? Code required a main breaker only if there were above a certain number of circuits.
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  292. I don't like tamper-proof receptacles. If you have a ground fault interrupter, there is no point to having a tamper-proof receptacle. Particularly where there are no small children.
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  293. Donkeyno9 — That isn’t really wrong. The voltage should be in a range of 110-120 or 220-240, depending on where you measure it and what is happening in the supply.
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  294. Josef — We do, but you can’t put it in a residence. It’s 480V delta, or 277/480V Y.
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  295. Joe the Stack — Interesting problem. Was it a new installation?
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  296. 1crazypj — There are many plugs and sockets. Some are cheaper than others. The most commonly available parts are Leviton. I don’t like them because they do seem cheap. I generally by Eagles (which aren’t called that anymore), because they are sturdy “specification grade” devices. Plugs vary widely. When I buy an extension cord I try to get a good one. I just looked at a few of my plugs on various devices and most of them seem good to me, so I’m not sure what you think is an example of a cheap one. I like the flat prongs better because I think they have a more secure feeling when plugged in and they make good contact. I’ve used the European plugs recently, so am familiar with them. It is interesting that Harvey Hubbell’s first plugs for US power had round pins. He switched to the flat prong still used today because it worked better.
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  297. Transformers can increase voltage, but not energy. In fact, some energy is lost to heat in any transformer.
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  298. ammo2222 — Amps are not power. Power is the product of Amps and Volts.
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  299. Nobody but an electrician should be messing with commercial wiring.
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  300. I don't that's required in the main box in the US when the main dusconnect is in the same box.
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  301. David King — What would be the point of that?
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  302. What two standards?
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  303. We (in the USA) would put the switch in the wall next to the receptacle rather than in the plug. In fact there are devices which combine a single receptacle with a switch in the form factor of a duplex receptacle.
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  304. Fermitu Poupon — I encountered one of those special razor outlets in a European hotel recently. It wasn’t good for anything else. What a useless device!
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  305. chefboyjc — By “our” do you mean USA? A lot of people around the world just like to dis the USA for any reason, with or without merit. A lot of other people just want to come here.
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  306. Brian Leeper — That would be unusual, I expect.
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  307. Glenn De Jong — Load centers (breaker boxes) often come with a main breaker installed. What people really want is a lot of breaker positions, because it is convenient to be able to switch off small parts of your system, and because it is a pain to run out of room in your breaker box. This fellow has a lot of circuits, so his box probably came with a 200A breaker without ordering it separately.
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  308. 9peppe — You would do it because 208 between two phases is what you have available in some buildings. It is likely enough for an overnight charge.
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  309. Bio Emiliano — You won’t get a live ground if it’s wired properly. The ground is connected to neutral only near the main disconnect.
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  310. Janick Spielmann — We have Ground Fault Circuit Interrupters, and Arc Fault Circuit Interrupters.
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  311. Simon A — It is one phase, center-tapped. A duplex outlet is usually wired with both receptacles on the same side of the power, but it is possible to wire them with the upper receptacle on one side of the power and the lower receptacle on the other side of the power. Or, you might decide to have half of the devices switched for portable lamps.
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  312. A connection will also arc at 120V when unplugged. Generally, the things that can’t be turned off are low power devices like my cell phone charger. The arc doesn’t seem to do any damage to those. A higher power device is just turned off before being unplugged. Why does the switch need to be at the plug?
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  313. Wooden power poles are cost-effective, at least in North America. And they are nonconductive. There are not nearly as many problems with them as you imagine.
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  314. Paul Pantsoff — To which country are you referring?
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  315. Darwin award.
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  316. The North Americam electrical system is not executed "terribly." It is a practical system which has worked well for more than a century. As for switched receptacles, anyone can install one, if desired. Any easy way to do it is to use a single receptacle combined with a switch in pkace of a duplex receptacle. We can put switches wherever we need them. The most common use of a switched receptacle is to control a floor lamp which plugs into a receptacle. In that case we mount a switch high on the wall, not at the receptacle.
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  317. The skin effect is not important for low frequency AC used in homes. Besides, you just wire a home according to code.
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  318. pahom — Europe is 400, if two phases are delivered to the customer and if he can connect to and use 400V.
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  319. Stefan Jönsson — It is just the presenter’s unusual way of explaining things.
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  320. woowooNeedsFaith — The United States does not use Imperial Units. We were out of the Empire when those units were standardized.
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  321. Jean Emar — The breaker box is grounded. I have never heard of anyone getting a shock from the box. If you can find any authoritative statistics on this, please post a link. If a hot wire touches the box, there will be an arc and the circuit breaker will trip. The neutral wires are white. The lines are black. Of course if a breaker box is wired improperly, there could be a danger. That’s why only a licensed electrician should work on a breaker box. The neutral wire is not the ground, although it is tied to ground at the box. We (in the USA) do, indeed, have Ground Fault Circuit Interrupters (GFCIs). You are just making this stuff up. You don’t have to have a 200A main breaker. That is as large as they come for household circuits. A more typical value might be 125A.
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  322. kkuukkoo2 — It is usual for the individual circuit breakers to be sideways for any brand of panel. The geometry just works better. The convention is that the cicuit is on when the switch is toward the center.
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  323. John Irby — You don’t carry voltage on a wire. You carry current on a wire. Voltage is the potential difference between two nodes. We call a double breaker a 240V breaker because there is a 240V potential difference between the two wires other than the neutral. It’s more convenient to call it that. Besides, there does not have to be any current in the neutral for the breaker to trip, so it is not the same as two individual 120V circuits.
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  324. PhillC02 — I expect 120V service came into general use first, for lighting. Then the split phase system was developed as an upward-compatible way of providing 240V. That’s just a guess. We use 120V for most things because you don’t need 240V to brew coffee and such.
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  325. yoksel99 — Here, it is just a notation indicating that the legs are in opposite phase with respect to neutral. It isn’t really “wrong.” He may use whatever notational devices he prefers. It would have been better had he explained the point.
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  326. Wouter Weggelaar — You (in Europe) can have your clunky plugs. We don’t like them and we don’t need them.
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  327. DEmma1972 — I have never experienced arcing doing any damage to a 120V US-style plug or socket. I wouldn’t mess with a 240V plug without shutting off the circuit, even with the device off.
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  328. I have several AC motors in my apartment, running on 120V single-phase. There are countless such motors in operation everywhere. They work perfectly well. Heavy-duty electric motors are often 3-phase. Why would his house burn down?
    1
  329. The reason he has a 200A main breaker is because he has a large panel with many breaker positions. The main breaker is preinstalled in the panel and the largest panels will always have the 200A breaker.
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  330. Wuety06 — In the US, we have both, and combo breakers. Where did you get the idea we don’t?
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  331. The grid in the USA is high voltage, so the service can be anything. Residential service is conventionally 120/240, but higher voltage three phase service is available.
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  332. Large computer systems generally have special power installations. That’s true of industrial equipment generally. The power company will provide what you need.
    1
  333. The main problem with US electric connections is the proliferation of cheap receptacles.
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  334. Not necessarily. In a multiple dwelling building, you could have a three phase main panel, and single phase subpanels for each unit.
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  335. I would not take it for granted. The severity of the shock depends on how well grounded you are.
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  336. Gerwin Smelt — I’m not buying that. Europe adopted 50 Hz power not because it is safer (it isn’t), but only because they thought the number “60” sounded too American.
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  337. Darragh Finnan — We have Ground Fault Circuit Interrupters (GFCIs) and now Arc Fault Circuit Interrupters (AFCIs). The GFCI can be built into a receptacle or a circuit breaker. There are combination circuit breakers, but not for every application, unfortunately.
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  338. Michael West — If you want a switched outlet in the US, you can have one. An outlet is normally duplex, but you can buy a device with a switch replacine one of the outlets.
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  339. Np, it isn't. In N. America we typically supply 240v to residences, which supports 240v and 120v service. He explains how that works.
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  340. David Stewart — Not using a backing panel does seem daft. He probably installed it himself.
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  341. cosmolv — It should be about 417V phase to phase with 240V on each leg of a 3-phase system. Can you explain that? We (in the USA) have 480/277V.
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  342. Powder-phun — It is very rare to have it in a single-fanily home or duplex. Apartment buildings might have it, but it wouldn’t be provided to individual units. My condominium has it for the elevator, rollup doors, and ventilation.
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  343. ammo2222 — Ironic, because Schneider took over Square D. Yes, I know it’s a French company.
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  344. Not many people need 3-phase, but we (in the USA) have it if a customer needs it. I don’t see why a household needs it.
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  345.  @undeath6010  — You would have to show me a wiring diagram for such a range for me to understand it. Do you mean one heating element would be powered by one phase and a second heating element by another, as a way of distributing the load?
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  346. TheChipmunk2008 — What he is discussing is the common houshold power, which is 120/240vac. By referring to all those other voltages, you are just showing off. I’m sure European countries also have more voltages.
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  347. Our (North American) duplex receptacle can easily be replaced with a single receptacle with a switch.
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  348. In the North American system, we have both neutral and ground.
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  349. Fr David Joyce — Probably faster, but in any case motors manufactured in the USA will run properly on 60 Hz.
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  350. Such receptacles are unusual.
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  351. Simon Liu — Yet somehow Facebook and Google run huge server farms.
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  352. That’s a distribution “medium” voltage, not high voltage.
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  353. David James — They aren’t “phases,” they are “legs.” The N. American system is single-phase for hosehold use.
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  354. A 24 vac circuit is fairly common for doorbells, but there isn’t much of anything above that until you get to 120 vac, at least in residences. Low voltage lighting is 12v.
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  355. SgtMantis — The power company provides three lines: L1, L2, and Neutral. An AC potential of 240V (RMS) is placed across L1 and L2. N is connected to the center tap of the secondary, so Ln to N is 120V. Neutral is held to ground potential at the transformer. Common small devices, like a toaster, are 120V, so connected to one hot line and to Neutral. There is a circuit from the transformer to the load and back through the two lines, as with any other electrical system. Two 120V devices attached to different hot lines share the Neutral. Because the lines are opposite phase, The current in the Neutral is the difference of the individual currents in the hot lines. The Neutral will never carry more current than one hot line, so it is the same size. The ground circuit connects the metal of the system: boxes, conduit, and metal frames of devices. Ground carries current only when there is a fault, such as a hot wire coming loose and touching grounded metal. The ground provides a path back to the transformer because it is connected to neutral at the head end of the system, near the main disconnect. If there is sufficient fault current, such as from a short, a circuit breaker will trip. If there is a small fault current, a GFCI will trip the breaker.
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  356. It isn't "dumb" to keep using a system that has worked well for 135 years anf for which every building is wired and for which there are countless devices compatible with it. What is dumb is thinking that the differences between North American and European electric power are important enough to argue about. I have visited Europe. The only electrical device I needed to take was my iPad. It is dual voltage, and it switches to the supply voltage automatically. The only adapter I need is an inexpensive device to allow the charger to be plugged in. The voltage difference is not an impediment or inconvenience. I also have a couple of appliances made in Europe. They have power supplies designed for the North American market. The difference isn't great enough to make it impractical to sell European appliance brands in North America.
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  357. ⁠ @SandmannOZ — It isn't substandard, it isn't unsafe, and it isn't "low usability." I don't even know what you mean by that last thing. We have electric power for anything we need to do that can be done with electric power. It's just a little different than your system.
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  358. Doesn’t matter. It’s a range. It doesn’t have to be controlled precisely.
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  359. partizan forces — That’s why they are covered up.
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  360. Adam Antly — I would boil the water on my gas cooktop, if I drank tea. If I didn’t have gas, I would get a small induction unit. Those are pretty fast.
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  361. The transformer design synthesizes two 120V circuits 180° out of phase. It is just a way of looking at it, really, or a semantic argument. It is not a substantive argument.
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  362. I doubt literally every home in Europe has 3-phase service. Likely there are some homes which receive one 230V phase.
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  363. Westinghouse chose 60 cycles per second through experimentation when they developed their system. Better to ask why Europe chose 50 cps when 60 cps was already established.
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  364. TheKHfan358over3d — Anybody who wants a switched outlet in the American system can have one: https://www.gordonelectricsupply.com/p/Cooper-Tr291W-20A-120V-Cmbo-Sw-Rcp/6047313
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  365. I think electricians generally say “110” out of long habit. The voltage can vary throughout a range, of course, and be considered acceptable.
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  366. What is this baloney about poor receptacles in the USA? I have traveled to a few European countries in recent years, and my opinion is that US receptacles are far and away the best design. Granted, the most common brand found in hardware stores is junk, but I buy Eagles which are much better. Furthermore, the three-wire 120-N-120 system is better and safer. There is no need to use 220v or more for small appliances and lights. Our 110-120v receptacles have space for a ground pin, and also have polarized slots for two-pin plugs to ensure that the neutral side is connected properly for devices where it matters. The design also accommodates a slight modification to one pin for 20A devices to prevent them being used on 15A circuits. It’s an ingenious design which covers a variety of connections in one scheme. And, as you mentioned, we have 220-240v using a different connector. Then there’s 60 cycle vs. 50 cycle. AC power was invented by Westinghouse in the USA. They chose 60 cycle as the best compromise of efficiency and practicality. When Europeans implemented AC power, they rejected 60 cycle only because it sounded too “American.” But 100 cycle was less practical, so they chose 50 cycle. They were pretending that it had something to do with the metric system, when it really has nothing to do with it. For most things, the difference in frequency doesn’t matter, but nevertheless it is one of the stupidest decisions in electrical engineering ever made. It illustrates the difference in the way American and European engineers think. (Ironically, Nikola Tesla, who worked for Westinghouse, came from Europe.) Edit: “cycle” should be “Hertz.” I’m showing my age.
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  367. Normally, there is a cover on the box. The breakers can be operated with the cover on.
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  368. We don’t usually have a disconnect at the meter in the USA.
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  369. Philip Dillard — There is nothing weird about 208 120V 3-phase.
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  370. MaskinJunior — We do for industrial use, not dwellings.
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  371. The energy delivered to your body is what kills. It doesn’t matter what current an appliance carries. When a person receives a shock, the current will be determined by the voltage and by the resistance of the circuit of which the person is a part. So if you are well grounded, your body will provide a low enough resistance to receive a substantial shock. The current will be twice as high if the voltage is twice as high. That’s Ohm’s law — the first formula you wrote.
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  372. Wrong, but define "load."
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  373. Ruslan M. — Common household service is 240V single phase, with two 120V single phase sides. EU has 480 (or 400, or whatever) from two phases, so has 480V service provided that voltaged is delivered and made available to the customer. Does your electric water heater operate at 480V? If so, you have 480V service.
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  374. That “fact” is not something I am willing to test. I’ve been shocked by 120VAC once or twice in my long life. That’s enough for me.
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  375. Motors will operate over a range of voltages. That is not a significant difference.
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  376. Александр Мелихов — Why would you touch hot wires? Safety is not achieved by lowering the voltage, it is achieved by having proper installation of wiring and by using Ground Fault Circuit Interrupters.
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  377. tenraek — Aluminum wire was a bad idea. Knob and tube can still be found in old houses. It isn’t anything to fret over. Nobody installs it today.
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  378. It is a ground wire. The potential relative to the metal box is zero.
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  379. It isn’t simpler, just different.
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  380. Brian — I have never seen anything like that. It doesn’t make any sense.
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  381. Omar Abalkhail — Not likely. Only a smart device could reconfigure itself to use the same power at 208 and 240 volts. A simple resistive heater designed for 240V will draw less current at 208V and use less power.
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  382. Maxwell Greening — That’s just wrong. Ordinary households in the USA get a single split phase of 240V (two 120V sides).
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  383. robert linke — “The side of that thing ...” What thing? Please give the time.
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  384. We have never used Imperial units in the USA. We use US Customary units (and metric units). Imperial units weren’t defined until half a century after the United States left the Empire.
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  385. Nils Bergman — A homeowner may do his or her own electrical work in the USA, subject to permit and inspection. A license is not required. I installed a new circuit breaker box years ago, with no special credential. I wouldn’t do that today, though. I just finished an electrical project and hired an electrician to do it. But when I had to make one little change to pass my final inspection, I did it myself.
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  386. Ben Dover — You mean “huge.” His panel is not typical.
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  387. Electrocution is fatal by definition.
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  388. Herr Bönk — “Service” is not just the fuse or breaker, it is the wires, meter, electricity. The power company is selling a service to the customer — electric power at up to 100 amperes at 240 volts.
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  389. You could also call it 115/230. It is all the same. Your voltage may differ.
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  390. MyTech — The 20A 240V outlet has one prong turned sideways.
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  391. All color conventions work equally well, because the electricians know the convention in use where they work.
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  392. “Runs on” doesn’t mean anything as used above. We have motors that run on 120V or 240V or something else. The North American power system just supplies the voltages needed.
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  393.  @Pitoco367  — We know that, but this video explains the North American system.
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  394. The thermostat senses the heat, not the voltage. As long the oven produces enough heat on 208V to reach the set temperature, it will work properly. It will take longer to preheat, though.
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  395. ralmslb — The main breaker comes preinstalled in a panel with that many circuit positions, whether you need it or not.
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  396. Ram-n_dodge — Yes, and it’s a nuisance when doing work. An inspector reviewing my plan told me to use an afci on a particular circuit. My electrician said he had use a double-pole breaker to replace two singles, for some obscure reason I didn’t understand. But for my type of panel there is no combo double-pole breaker available. So he put in a gfci breaker, saying that was more important. I was worried about having to explain this to the final inspector, but as it turned out he didn’t even raise the issue and I passed final in about five minutes. That’s what I hate about electrical work. Every few years they think of something new which causes trouble when working on old circuits. My view is that if the authorities are going to require both gfci and afci, then they ought to first require every manufacturer of breakers to make a combo device for every type of breaker one is likely to need. If I were building new, I would choose a panel type that offered a combo breaker for every circuit I needed, because I would rather have the gfci in the panel than on the wall.
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  397. Gregg Weber — There is no problem with that arrangement.
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  398. We don’t all have 200A service. I live in an apartment and have a 60A breaker for my unit.
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  399. You need a receptacle which is wired across the two sides of the electric service. There are a few types of receptacles for 240V. Consult NEMA for information. Then you need a matching plug on your 240V device.
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  400. No, we don’t use twice the copper in the USA. In order to compare the efficiency of copper use, you would have to audit a complete distribution system. The organization of the distribution systems is quite different between Europe and North America. Considering just one piece of the electrical system is not meaningful, especially when it is done only theoretically, not by actual audit.
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  401.  @hardrout17 — Simplistic “analysis” is not helpful. Electrical engineering portal is a good place to see European and North Americam electrical systems compared.
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  402. Paul Dixon — I’ve had two European condensing dryers because I don’t have a vent. They both failed. Now we just do without a dryer because our climate is dry enough to air dry. I wish an American company would make one so I could get a reliable one.
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  403. Okuno Zankoku — All this back-and-forth over what to call things is silly. I would just say “US household power.” I know how it works. When I go to Europe I make sure I have the adapter I need for any device I intend to use.
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  404. It’s short for “gasoline.” I assure you, nobody is confused by this.
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  405. pd4165 — In some places, we do. It’s much more expensive, so generally done only in densely populated areas, and then only when the residents are willing to pay for it.
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  406. I would never try to use European electrical equipment which had not been adapted for use in the USA by the manufacturer. I do have a couple of European appliances, but they are US models.
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  407. dynorat12 — In the US, they are bonded only near the main disconnect. Otherwise, they are separate circuits. The ground normally does not carry current, but in the event of a ground fault it must complete the circuit to the main panel neutral in order to trip the circuit breaker.
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  408. Wrong. If you lower the voltage to an incandescent lamp, it will consume less power and it will be less bright. You won’t get much light out of a 100W lamp if you operate it at half voltage. This is basic.
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  409. RomaineRC — That’s the tradeoff when you use a higher voltage. At 120V, it isn’t a problem. In technology, everything is a tradeoff. There are different ways of doing things, and often there are advantages and disadvantages to both alternatives.
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  410. CaberFeidh — The peak-to-peak voltage is not important to the subject of the video. 60 Hz is more efficient. That’s why Westinghouse chose it.
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  411. John DoDo Doe — Was undergrounding in urban areas done as a part of general rebuilding, or was that common before WW II?
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  412.  @kylejohnson4662 — In my case, they are just the two separate kitchen receptacle circuits. There is no connection between them except the coupler on the toggle. I think the electrician thought they might have a shared neutral. They are GFCI breakers, so a fault on either circuit will trip both.
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  413. Sigfrido Gil — I’ve been zapped by a 120Vac circuit when I was young and reckless. It wasn’t pleasant, but I lived. It was within one arm, though.
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  414. No. He has an unusually large breaker panel, even for the US. He probably drives a large pickup or SUV.
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  415.  @jeffm2787  — The way to understand it is to think of the two 120V circuits individually. L1 and N make one circuit; L2 and N make the other. Becase L1 and L2 are opposite phase, their currents will flow in opposite directions on N. Thus they subtract rather than add.
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  416. Dinky — Why do you think we can’t make tea? I expect a countertop induction heater would be the fastest way to boil water for tea.
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  417. Voltage is not what does work. Power, volts times amps, does the work. As for for 3-phase, we have that also, but households don’t need it. At home, we power lights, make coffee, and charge our phones. We have small motors in appliances. None of these requires high power. Commercial and industrial buildings have higher power 3-phase service to provide wide-area lighting, and run elevators and heavy equipment. The United States has never been held back in industry by its 120-volt residential electric service.
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  418. electro1622 — “Illegally”? You are just making this up.
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  419. Nathan Kayle — We do have 240V outlets available, but there aren’t many devices that use them.
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  420. Marcos Victor — Which wires, exactly? A common 20A outlet is wired with #12. That’s a little over 2 mm. What wire size do you use?
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  421. agentcrm — No, common household electric service in the US is single (split) phase.
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  422. SolarizeYourLife — Now consider the cost of replacing or modifying all of the 120V devices.
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  423. SolarizeYourLife — The neutral wire in the service drop often is aluminum.
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  424.  @victorseastrom3455  — It’s a high impedance device. Current is voltage divided by resistance, according to Ohm’s law. When he selects a voltage range, appropriate resistance is switched into the circuit.
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  425. It doesn’t, usually. This has been explained in the comments.
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  426. Nathan — I don’t believe we (in the US) do. I would have to see a detailed analysis to believe that. Hand-waving won’t do. Start with your distribution transformer and add it all up for a typical number of homes. Then draw an equivalent American system and add that up.
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  427. Is that what we call a Ground Fault Circuit Interrupter in the US?
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  428.  @francocozzo7235  — The US has breakers with a built-in ground fault protection feature. We install them on individual circuits, not the main for the whole box. Old work may not have them, because we are only required to upgrade our wiring to newer standards when it is being worked on.
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  429. andywolan — You don’t understand it. You have it wrong. Listen to it again and read all the comments.
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  430. Gunnar Parment — The ground pin on a US plug is also longer than the other two.
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  431. It isn’t about 3-phase.
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  432. Every electrician knows the convention. It isn’t a problem. Red is used for another purpose.
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  433. We can get 3-phase for residential use, but few have it. A normal connection for a residential electric range is 50A at 240V, or 12 kW, single phase. There are some 3-phase induction cookers available in the US. They require 208/120 3-phase power They are more likely to be found in commercial kitchens. A Garland single-hob induction range is 5 kW.
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  434. Lee — I don’t doubt it is safer, if ground fault interrupters are in common use. We have them, but they are mandated only for new work.
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  435. David Stenström — No, the US distribution system is mostly 3-phase. One phase is transformed to the household 3-wire system near the customer.
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  436. Plague — They do, if two phases are delivered to the home and receptacles supplied to use it.
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  437. In N. America it is usual for there to be a neutral connected from the substation to the customer’s wiring.
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  438. Álvaro Andrés — You are just playing with words. The common household electrical service in the US is 240VAC split-phase, which supports both 120V and 240V circuits.
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  439. It is prudent to switch off the circuit at the panel when messing with the 240V plugs. I expect she learned a lesson.
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  440. Ground and neutral are different wires. The ground wire at a 240v appliance would always be connected to the chassis. If a neutral were at the outlet, it would be unused if the appliance had no 120v circuits.
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  441. Anima — He no doubt put the cover back on. We don’t leave our panels open.
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  442. DarkEvilgenius — Sure we do, just not in dwellings. In a commercial or industrial setting, you can get higher voltages.
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  443. That’s the same thing. It is just another way of looking at it.
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  444. Wher I live in the US we are now required to have child-proof outlets like that, so I had to put them in when I had some kitchen work done. I hate them, and had already bought some high grade devices, so bought cheap ones with the child-proof feature to get through the inspection, then changed them back. Considering that the outlets are above the kitchen counter, protected by a ground fault circuit interrupter, and that there are no children in my home, they are completely safe. I know the people who develop codes are just trying to keep everyone safe, but sometimes their requirements are just a nuisance.
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  445. Systems Science & Maths — I studied a schematic of a gas refrigerator a few years ago and figured out how it worked, but I couldn’t explain it today.
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  446. Horace Wong — If I (in the US) had a work bench with a soldering iron, I could very easily install a switched outlet for it. This sort of complaint is unrelated to the fundamental differences of the various systems.
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  447. Henrik Jensen — If you deliver the 400V to a customer, who may connect to it, then the customer has 400V/230V service. But you could deliver only the 230V, in which case the customer has 230V service. It is clearer to think of it from the point of view of a customer, because any power system has many possible configurations, including that in North America. By the way, what does a 400V receptacle look like?
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  448. That’s just the size of his main breaker. He has a large box with the capability of holding many circuits. It probably came with the breaker installed. It is the maximum size because of the size of the box.
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  449. andy parry — Undergrounding wires is not cheap. In the USA, we usually put wires underground only when the customers agree to pay for it. New developments are likely to have underground piwer, because the developer incorporates it rather than leaving it to others who buy into the development. Then there are economies of scale. You will see the most poles in older areas which were developed piecemeal, not as a single project encompassing a neighborhood.
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  450. Roger Moore — You can get 240V lawn mowers. Nowadays there are cordless mowers, but I don’t know how well they work. Gasoline-powered mowers are most common in North America.
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  451.  @vicroc4  — Yes, you get a 120v circuit out of either a 3-prong or 4-prong 240v receptacle. It seems to me that an appliance which is designed for a 4-wire receptacle should not be used on a 3-wire receptacle. I would read the installation instructions carefully before doing that. It would be better to upgrade the circuit. You are just wrong about the 240v circuit, though. It is single phase. What we sometimes call “2-phase 120v” is synthesized from a 240v single phase transformer by putting a center tap on the secondary. It is better called “split phase.”
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  452. Odd Fellow — I don’t have an electric kettle, but I have an electric coffeemaker. It stays plugged in almost all the time. Why would I unplug it? When I do unplug it, it is turned off on the device. Why would I unplug it if it were on?
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  453. Dick Bateup — Sixty cycles was found to be the best balance of efficiency and practicality when the AC power system was developed by Westinghouse. The Europeans adopted 50 cycles for reasons having nothing to do with engineering.
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  454. We implicitly use RMS when referring to AC voltage.
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  455. Edison actually used 110 VDC in his system. That’s why our US AC systems started out generating 110 VAC (RMS), so the lamps would be compatible. It was later increased to 120 VAC.
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  456. Children are not dying by mishandling US power plugs. In my long life, I was shocked once as a child from a 120V outlet. It isn’t fatal. The only eal danger is using electrical devices while in the bathtub. Don’t do that! The solution is to have ground fault circuit interrupters on every circuit with outlets.
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  457. A Christian — Have you asked your power company whether they can provide 3-phase in your area? If the answer is no, maybe you can set up a shop in a nearby commercial zone.
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  458. Ed French — I’m sure that isn’t significant. A higher current will dissipate more heat, but a higher voltage will spark across a larger gap. If you want to avoid fires, you need wiring that is properly designed and is in good condition.
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  459. vuortenpoika — It is not live wire. It is a grounding wire.
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  460. Please spell out your terms.
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  461. That’s a term which is sometimes used. It doesn’t matter what term you prefer. It is what it is.
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  462.  @uTube486  — No, you are just quibbling about terminology. We know what the waveforms look like.
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  463.  @uTube486  — If you use the term “split phase” for something else, why not say what it is? I don’t care for the term myself. I would just call it the North American 3-wire residential power system (NA3wRPS), but that’s a mouthful.
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  464. Victor Johnson — There is no “standard” on that. In newer buildings, 20A circuits are common.
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  465. Andrew Owen — By “leakage current” I assumed he meant ground faults.
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  466. John Goldsmith — Nobody actually gets shocked on the prongs. It’s a purely hypothetical risk. When one has small children, a room where they may play unsupervised must be childproofed. You remove all the cords and put plastic inserts in the outlets. But nowadays, with ground fault detection, the risk has been eliminated.
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  467. sween187 — We can, but it isn’t commonly wired that way.
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  468. M G — All this is true, but the argument is pointless. There is just a lot of one-upmanship going on here. It is what it is. Learn how it works if you want to, or don’t. It doesn’t matter. We all have electric lights in our homes and motors that move things. It’s all good.
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  469. Brian Gregory — The common 3-wire systen used in North America is rooted in history. It would be vastly difficult to change it and there is no particularly good reason to do so.
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  470. AC voltage is expressed in RMS, not peak-to-peak. 240V RMS is 679V peak-to-peak.
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  471. What he wants is a panel with a lot of circuits, which probably comes with a 200A main breaker installed. He may never get close to the current capacity of the breaker.
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  472. I guess the bill would be lower because so many things won’t run on 240V. There’s no place to plug in his vacuum cleaner so he has to sweep.
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  473. Scott Plumer — In the United States, you can get a combined switch/outlet if you really want one.
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  474. He does. It would be zero, because they are on the same bus.
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  475. His large panel is not typical for a single family residence.
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  476. No, 3-phase doesn’t work that way. You can’t put the three phases in series. If you have a 4-wire Y service with 240V on each phase, you would have 416V phase to phase.
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  477. Tomie Dotson — Look at your pen-penultimate sentence carefully.
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  478. Tomie Dotson — Here is the word on box bonding from Schneider Electric: https://www.se.com/us/en/faqs/FA100207/ The box is grounded.
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  479. Wheelie-bin Workshop — The United States has done fairly well with industry and technology.
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  480. Normally, there would be a cover on the panel.
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  481. JanTube — We know it is weaker. It is lower voltage by design. We prefer it. We can make higher voltages when it suits us.
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  482. Scott smith — Question from USA. Why don’t you spell those terms out so we know what the heck you are writing about? Example: We do have Ground Fault Circuit Interrupters (GFCIs) in the USA.
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  483. RogerWilco — To what country are you referring?
    1
  484. Your expectation is peculiar. Customary units don’t fit neatly with Metric units because they originated in antiquity. Units related to electricity originated in the nineteenth century, after the Metric System was already established.
    1
  485. Slavko Glamočanin — So how would you convert heat to electricity?
    1
  486. The best plug is the one that fits the receptacle you have available.
    1
  487. PyrusLex86 — You can have a switched outlet in the American system. It isn’t brain surgery.
    1
  488. Does Not Exist — We know how to do those things in the US.
    1
  489. We (in the USA) take one phase from the 3-phase distribution network to supply 240/120 split phase for residential service. If 3-phase power is needed, it would usually be either 208/120 or 480/277. Only commercial customers would get 480/277.
    1
  490. Linus Persson — It must be poor presentation, because it is very simple. If you are familiar with a 3-phase “Y” service, here’s how you can derive the North American system from the 3-phase “Y”: 1. cut off one phase and associated line 2. change the phase angle to 180° 3. change the voltage to 120V phase-to-neutral That’s all there is to it.
    1
  491. Wouter — Anybody who wants a switch on on outlet can have one. There is no rule against it. One way to make US outlets safer is to replace worn-out outlets with a better grade of outlet which grips the plug tighter.
    1
  492. MigotRen — You don’t have to have 200A service. Many households can get by with 125A. I wouldn’t go lower than that.
    1
  493. Doc Daneeka — We have ground fault circuit interrupters available for individual circuits.
    1
  494. The US national standard is ANSI C84.1. You have to distinguish between service voltage and utilization voltage. The current service voltage standard is 120 + or - 6. Utilization voltage is a little lower.
    1
  495. In the beginning, we had only 110V. A lot of useful things were made using that voltage. It was later raised slightly, and the 240V system was designed in a way that was compatible with the lower voltage, so as to not make everything operating at that voltage obsolete. Devices designed for 120V work perfectly well, so why change it?
    1
  496. Our split-phase system is a simple standard with a lot of history behind it. By the way, we have never used the Imperial System in the United States. We use US Customary units.
    1
  497. Dokter Roetker — Because my coffeemaker requires 110V. I have to have my coffee!
    1
  498. repoman — No, the transformer acts like a transformer, which is what it is.
    1
  499. It is better to have a properly wired 240V receptacle where you need one. Let an electrician do this.
    1
  500. LegosheepIsAwesome — You could turn off an entire circuit at the breaker.
    1
  501. SilentServiceCode — A flammable gas that comes out of the ground. It’s a mixture of gaseous compounds.
    1
  502. A Karim Siddiqui — Neutral and ground are not the same.
    1
  503. SkyEarthOcean — People with EVs often install a 240v charger.
    1
  504. The United States standardized on 60 Hz because Westinghouse found that to be the best compromise of efficiency and practicality.
    1
  505. andreas eversberg — In a residence in the US, you might be able to get 208/120 3-phase. If your device will run on 240, it might work on 208. A better option is a 240V single-phase to 3-phase converter.
    1
  506. NZ2Pepper — “Split phase” is not a good term for it, though, because it has other meanings.
    1
  507. A 60A service used to be common. I have 60A service, but is just for a small apartment with gas for cooking, heating, and water heating.
    1
  508. People always say that, but they don’t say what gauge wire is used for a common 230 vac circuit in European homes. Can you provide a link to a specification which documents this? For comparison, we use AWG #12 for 20 amp circuits, which are typical in modern construction. We can use #14 for a 15 amp circuit. Edit: I found this for UK wiring on diydoctor.org.uk: “In most domestic situations the cable size used for sockets on a ring main or radial main is 2.5mm twin and earth cable.” AWG #12 is 2.05mm diameter, so I don’t see where the saving is. AWG #14 is 1.63mm diameter.
    1
  509. Ram Shor — Do you mean from arcing when disconnected under load?
    1
  510. Our North American electrical grid works well. There is nothing to learn about power distribution. It is a mature industry in both Europe and North America.
    1
  511. A 240 vac receptacle may have two, three or four connections. When there are three wires, the third may be neutral or ground. In a 4-wire connection there is a neutral and a ground. See NEMA for recptacle types.
    1
  512. NMTCG — Ground should be connected to neutral only near the main disconnect.
    1
  513. David Garcia — Do you mean transformer? He said it was for the doorbell.
    1
  514. David Garcia — The transformer produces 24 vac., which can be run anywhere with a twisted pair of lightweight wire. No conduit or outer sheathing needed. You can feed it through a small hole to get it where you need it. It is much easier than putting the transformer near the doorbell.
    1
  515. It must have been a poorly made computer if it wouldn’t run on anything 110v to 120v. I’ve never heard of that problem.
    1
  516.  @RandomTorok  — Yes, but what brand was it?
    1
  517. Things like phone chargers don’t have switches, at least in the US. We just plug them into hot receptacles. At 120V, it isn’t a problem. There isn’t enough current to damage the plug or receptacle.
    1
  518.  @TheThickSherpa — The phone charger plugs into 120V and produces 5V for the phone. Things that use significant power, like a coffeemaker or other small appliance, have a switch on the appliance. A small soldering iron is typically about 25 to 100 watts, which will not damage anything if plugged in without a switch.
    1
  519. Rutzki 29 — No question earth leak breakers make the system safer.
    1
  520. Chris — We (in the USA) can get higher voltage service when there is a need for it, but for household use there is no need for more than 240Vac. What is your point here? What do you do with 400V?
    1
  521. Andrew Young — We have 277/480V Y 3-phase, for those who need it. Or 230/400V.
    1
  522. Wolfram Sandig — Yes, 400/230V 3-phase is the way to describe that.
    1
  523. many have.
    1
  524. Electrocution is fatal by definition. You probably just got shocked.
    1
  525. Yes, there are 2-pole GFCI breakers for 240V circuits on the North American split phase system. They trip when the two lines are not balanced.
    1
  526. Moritz Hübner — So, what? I use E.
    1
  527. Mike Page — The only fuse upstream from the main breaker is on the primary of the transformer. I don’t know what it takes to blow that.
    1
  528. Lesserthannone — In the US, sockets are now being made with protective shutters. You have to push on both shutters at once to open them.
    1
  529. I don’t see how it has anything to do with safety. The problem with unplugging something which is operating is that there is a small arc as the connection separates, which could, over time, damage the receptacle. In practice, it isn’t a problem on our 120V circuiits, because mostly low power devices like phone chargers lack switches.
    1
  530. What devices actually use the 400V potential? Resistance heating, I suppose.
    1
  531. Jean-Michel Bocal — I have never heard of anyone getting shocked using one that was in good condition. I certainly have never been myself. In my opinion, they are suitable for our system. Modern Hubbell plugs have a flange just before the prongs which prevents your hand sliding forward as you push it in. That’s a worthwhile improvement.
    1
  532. Not really. The US distribution system is 3-phase, but, typically, only one of the distribution phases is used to provide 3-wire service to a residence. The 3-wire split phase organization can be thought of as a 2-phase service, but it lacks the directional property of a 3-phase system, so a 240v motor for the US 3-wire system is a single phase design, not a 3-phase design.
    1
  533. You are paying for the energy you use. The meter figures that out somehow.
    1
  534. Lex Smith — I have been to Prague recently. I’m not buying it. Besides, we do have 3-phase service in the USA, if you have a need for it.
    1
  535. It is pointless to argue about such things. Just explain how it works and leave it at that.
    1
  536. He is not using the full power capacity of his panel. He has a 200A main breaker merely because he has a lot of breaker positions. The panel probably came with the main breaker pre-installed.
    1
  537. Alastair McCormack — What is it you don’t like about them? I just put a couple of brand-new switches in my kitchen. They are conventional toggles, but smooth and quiet instead of the old snap-action mechanism. Still the best design for a switch, in my opinion.
    1
  538. I have one of those small soldering irons that have no switch. They have always been that way. Normally, you would just leave it on at a workbench and unplug it when no longer needed. Some workbenches might have a switch for a row of outlets, so you would just turn off your entire bench.
    1
  539. When a circuit is dedicated to one device, there is no point to its having a larger rating than necessary. For example, my furnace circuit is 15A. There is no place to connect another device to that circuit. A 15 A circuit may be wired with 14 guage copper wire. I don’t know if mine is. Since it’s the only 15A circuit I have, it might be wired in 12 guage like the rest. There could be circumstances for which the cost differential was important, not for an individual homeowner, perhaps, but for a builder.
    1
  540. Anything unfamiliar can be considered weird. For people in the USA who have worked with our power system and understand it, it is normal.
    1
  541. A shock from 120V can be fatal, but usually when a person is well grounded and the path goes through the heart. I’ve been shocked just once or twice in my life by 120V, and it was not life-threatening. Most electrocutions in the United States happen when someone disregards basic safety protocols, like using an aluminum ladder near power lines.
    1
  542. Vivisect — Not just breakers, but ground-fault interrupters. Often, they are combined with a receptacle.
    1
  543. A. Volt — We boil water on our gas cooktops.
    1
  544. Yiannis Mantheakis — An ordinary household does not need polyphase power.
    1
  545. Keith A. — That’s a whole ‘nother problem, though.
    1
  546. Hundreds? In my whole life (I’m retired), I think I’ve been shocked twice.
    1
  547. Edward Skinner — Is that true that every household circuit in the UK is ground fault protected? When did you start doing that? How long did it take? What did it cost?
    1
  548. The argument about what to call it is a tempest in a teapot. He is explaining how the split phase North American system works, and that is what matters.
    1
  549. G. Reynolds — That fourth digit is not significant. We don’t control the voltage that accurately.
    1
  550. Are you serious? When the AC power system was developed in the United States, 60 cps was chosen for engineering reasons as giving the best balance of efficiency and practicality. Our engineers do not have a notion of one number being uglier than another. We just want the number which works the best. This illustrates the difference between American and European sensibilities.
    1
  551. The bare copper wires are grounds.
    1
  552. mrcrtking — A center tap break alone would be almost impossible to come by. A tree falling across your service drop would take out everything. I don’t see where else it could break at all. The power company’s connection to the transformer is pretty sturdy.
    1
  553. His explanation is correct but his drawing could be better. It is 120° phase-to-phase (the red arc) in a 3-phase system. If you rotate the phase marked “120 V” to be opposite the phase drawn at the bottom, adding the dotted blue arc to the red arc, you get 180°.
    1
  554. Ugly German Truths — So? The UK has “toy” aircraft carriers that can’t launch anything but short takeoff aircraft because they don’t have catapults.
    1
  555. stickyfox — Yes, it’s a range 110-120V in which the voltage should fall. It need not be precise to the Volt.
    1
  556. Now look up “nominal.”
    1
  557. The United States has never used the Imperial System.
    1
  558. It looks better and is safer when the cover is on.
    1
  559. Sean Young — There is such a thing as 2-phase, but US household power is a single split phase.
    1
  560. Andrew Lankford — The people who design the transformers do that.
    1
  561. He isn’t trying to compare it to anything. He is just explaining how it works in the US.
    1
  562. Paul S — I have found traveling in Europe recently fairly easy, because the devices we needed are compatible. All we needed was the adapter for the plugs.
    1
  563. Yes, our distribution system is 3-phase. Residential customers are usually connected to just one phase.
    1
  564. Breakfast of Champions — What is a “professional” appliance? We have three-phase service available in commercial and industrial zone, for heave-duty motors and such. Motors for household purposes, such as for a freezer or dishwasher, are single-phase induction motors. For larger motors, you might use a 240V circuit.
    1
  565. Jolyon Welsh — It’s the most common, not “the standard.”
    1
  566. Elvin Haak — Some homes do not have gas. Some homes do not have a 220V range circuit. Some homes have both. I have never seen a range that combined an electric oven with a gas cooktop. If I were building a new kitchen and wanted that, I would get a gas cooktop without an oven, and a wall-mounted electric oven. Or I might have a regular gas range and add a second electric oven.
    1
  567. GBiv78 — We have switched outlet devices. Anybody can have them, but they aren’t widely used. I have one.
    1
  568. At least a hundred years. About 120 years ago, we started delivering 110 vac to homes, which eventually became 120 vac. Some time after that, the 3-wire service was added to support 220-240 vac devices while retaining compatibility with 120 vac service. Most people didn’t need 240 vac at first, so there were many homes that had only 120 vac service. Eventually, as older homes were replaced or renovated, 120/240 3-wire service became nearly universal. Light commercial might make do with basic 120/240 vac service, but large commercial and industrial customers will have 3-phase service and higher voltages available.
    1
  569. Large commercial and industrial customers commonly have 277/480V 3-phase service. Nobody needs 400V in a residence.
    1
  570. Take it easy! Conceptually, you can thnk of the North American system as 240V with a center tap, or two 120V phases 180° out of phase. They are equivalent. Quibbling about terminology is not helpful.
    1
  571. Germans had to rebuild their electrical grid in the mid-20th century. Good opportunity to upgrade.
    1
  572. The main breaker probably came with the box. His breaker box has a lot of slots and the breaker size is just determined by the number of slots. This is about as large a breaker panel as you will see in a US residence and 200A is the largest residential breaker. It doesn’t mean that his load is near that value.
    1
  573. What is a differential switch?
    1
  574. Carl hall — The RCD doesn’t have anything to do with the ring. The ring seems to be just a convention for running the wire.
    1
  575. We don’t have 2800W electric kettles. We boil water on our cookstove. A common 20A 120V circuit could nominally support a 2400W device, but in practice 1800W is typical. If you want a higher power appliance in a US kitchen, it is better to install a 240V circuit for it.
    1
  576. The main breaker is at the top of the panel.
    1
  577. All modern AC power systems are fundamentally the same, differing only in some details.
    1
  578. What’s the confusing part? Any electrical engineer should be able to understand the North American system easily.
    1
  579. Kevin Beaudoin — When you install a 240V breaker, it connects to the two hot lines. Then you can connect a load intended for 240V to the breaker.
    1
  580. Even the 240V outlets are 120V to ground. The main reason for 120V is historical, though. That is how it started (perhaps 100 to 110).
    1
  581. The code inspector would not approve it. I have used European plugs. They are not an improvement.
    1
  582. We do not routinely deliver 3-phase service to residential customers because there is no need for it. We use a single phase of the 3-phase distribution network to deliver 240v single-phase service, and we split it with a center-tapped neutral in order to get 120v. It is done this way because 110-120v service was established in the early years of electrification. The 3-wite system was introduced in order to get 220-240v (which is necessary), while retaining compatibility with 120v devices.
    1
  583. You can get 230/400 3-phase in some areas. Commercial buildings might have 277/480 3-phase.
    1
  584. We use 60 Hz in North America because Westinghouse determined that it was the most practical when they were developing the AC power system we use. Your question ought to be: why did other countries use 50 Hz instead of following our lead? It was their choice.
    1
  585. Jule Rulez — 120V isn’t very good for electric heating. I have a portable electric heater with three heat settings. At the high setting, over time, it ruined an extension cord I thought was heavy duty.
    1
  586. You don’t have to watch everything, you know.
    1
  587. Jan Brill — The trip current is marked on the toggle. The designation 10kA is the fault current it will carry without damage.
    1
  588. Andi Biront — The United States was a member of the 1875 Convention du Mètre, and we have participated in the development of metric standards ever since. We do use metric units in many contexts.
    1
  589. Andi Biront — In the USA it is the U. S. Customary system of units. I grew up with that, so it seems normal. I was on a science track in school, so naturally we used metric units. I have no memory of them being taught, so I am not sure when they wete introduced. They don’t require teaching, really, in science classes. We just used them where necessary. In those days, the 1960s, I don’t remember anybody getting worked up over units. People just used whatever suited their purpose. It wasn’t until later, when some people thought we should abandon customary units, that things got contentious.
    1
  590. Andi Biront — According to my wife, a retired teacher, California schools teach measurement in 2nd through 4th grades (she did not teach higher grades), and metric units are taught along with customary units. By 4th grade, students should know what it is and how it works. We no longer try to indoctrinate students, though. There may be some science teachers nowadays who are snotty about the fact that we didn’t give up customary units, but in my academic experience I honestly never encountered the antagonism over units that we see today. Perhaps it is just that the web gives a platform for the few people who get worked up over such things. Americans are practical people. We use what works.
    1
  591. No. If you want clean power for delicate devices, you use a filter box in the power line.
    1
  592. We also have 3-phase service for those who need it.
    1
  593. sara — very carefully!
    1
  594. 1873Winchester — Ok, but what does phased power actually do for you in a range?
    1
  595. Eric Cartman — Whinging about colour is really a stretch for something to complain about. The most important thing is to distinguish hot, neutral, and ground, and the US does that. Sometimes, another colour is helpful, but usually not. You can label individual wires as you install them, if you like.
    1
  596. David Earnest — More like 7200V at the pole, but it varies.
    1
  597. There is a large continuous range between the shock you will get from 120V while standing on a dry floor vs. standing barefoot on a wet floor in contact with the ground.
    1
  598. Kevan Gordon — Wire nuts work pretty well, but it is better to run wires continuously from the circuit breaker to the outlet. As for the tape, my electrician has some special tape for that purpose which he used when installing an outlet. I had never seen it before. It would only matter if you were removing or installing an outlet while it was live.
    1
  599. oliver sommer — I don’t understand what you want us to consider. Do you just mean undergrounding our power lines? We know how to do that and we do do that, whenever someone wants to pay for it.
    1
  600. US electric stoves operate at 240V.
    1
  601. We always use RMS when discussing AC.
    1
  602. There would not be any point in having both sides of the transformer be in phase. That would just be equivalent to having one winding.
    1
  603. Most small appliances have switches on the device. We don't usually plug and unplug such things hot. One thing that generally does not have a switch is a cell phone charger. They are plugged in hot, but the current draw is so low that the arcing is insignificant.
    1
  604. More or less, but you have two phases of a 3-phase system. The US has 2-phase (or one split phase), usually.
    1
  605. Kelly Hilding — Yes, the common outlet is 120V. The 240V outlets are usually for certain appliances, most often range and clothes dryer. You could also have air conditioning or electric heat on 240V.
    1
  606. wat — In the sense that we use 240V, but not exclusively, and metric units, but not exclusively, you could say that. We value freedom of choice here.
    1
  607. In the USA, apartments might be served with 3-phase power, so have 120/208 VAC, but most residences have singl (or split) phase 120/240 VAC.
    1
  608. right
    1
  609. Hugh Davey — It does go back to Edison. He developed his incandescent lamp, and a system for distributing power to his lamps over some distance, and settled on 110V as the best choice, for whatever reason. Then when AC came in, the same voltage was used because there were lots of lamps by then. Eventually, it was realized that a higher voltage would be useful, so the three-wire dual voltage system was adopted. That was necessary because there were many 110V devices as well as lamps. It works well, so we have stuck with it, but the voltage is now a nominal 120, which is about 117 average, in practice, I’ve read.
    1
  610. BoltActionPiano — What is a “240 standard outlet”? It seems that what you need most are more circuits for the outlets. They should be 20A circuits, also. I have only one 15A circuit, with only one dedicated device on it.
    1
  611. My cell phone charger has no switch, so when I unplug it there is an arc. But it is a low power device on a 120v circuit, so there is no damage whatsoever. Higher power devices have on/off switches.
    1
  612. Dan Pete — Must not have been properly grounded.
    1
  613. Ben Holroyd — If you have a workbench where you like to keep a soldering iron plugged in, you can have a switched outlet using any country’s system.
    1
  614. Bart Massey — That’s a sad story. It can’t have been the usual outcome, though. I’ve never read of a general disaster in implementing rural electrification. I wonder how the program was administered. Weren’t there handbooks explaining how to install wiring? I suppose there weren’t many electricians in the country.
    1
  615. maxie fuqua — Tennessee climate is quite different from Great Britain climate. There are parts of the USA where air conditioning is uncommon, such as the Pacific Northwest.
    1
  616. Distribution lines can be any of a number of different voltages in the US. It doesn’t matter to the customer.
    1
  617. CarsonG1017 — In the US, a double breaker is used for a 240V device. It is a 3-wire system. There is 240V between the two black wires, and 120V between either black wire and the neutral white wire. A double breaker breaks the two black wires simultaneously.
    1
  618. Tony Eyles — It’s just a switch with automatic features. What do you think it should look like? Since it’s hidden inside a steel box, why does it matter what it looks like?
    1
  619. robin barnes — I’ve had them and I think they are good. Can you explain this?
    1
  620. It’s a matter of point of view. It can be thought of as two phases of 120V at 180° out of phase, or one phase of 240V with a center tap. They are equivalent. What you call it isn’t worth arguing over, as long as the picture you draw of it is correct.
    1
  621. Bill Elkins — Square D was an American company which was acquired by a European company. Their current products are based on American designs.
    1
  622. alch3myau — What do you think a circuit breaker should look like? It isn’t a fashion show. American engineers are practical. We like things that work.
    1
  623. My cell phone charger does not have a switch. Aren’t most of them like that? I just plug it into a hot receptacle. No problem.
    1
  624. In the USA, 3-phase is available in some areas, although it not commonly supplied to a residence.
    1
  625. Matt R — The correct way to describe the ground/neutral is that the neutral is tied to ground at the service entrance. By “RCD” I think you mean Ground Fault Circuit Interrupter. We are supposed to have those on circuits with outlets near plumbing fixtures.
    1
  626. I don’t agree. Sometimes more volts are needed, sometimes not. There are some advantages to using lower voltage, mainly safety. Everything is a tradeoff.
    1
  627.  @markgrassl4449  —- Three phase is available in the USA. Single family residences don’t need it.
    1
  628. Ian Lavender — No, not dangerous. No, not undersizes. Why would I want a larger receptacle? There are larger receptacles for 240V, where needed.
    1
  629. You don’t need an adaptor. You just plug in a 240V breaker and connect a 240V receptacle to it.
    1
  630. ZeroDayVirus — I’m an old, stubborn boomer. I have lamps, small appliances, large appliances, and a few power tools that use 120v. If you told me I had to replace all those, I definitely would not like it. Of course you could design a transition plan that would mitigate the problem of having billions of 120V devices to support, but it would take a hundred years to implement. I’ve read that the United States did consider changing to 240V ca. 1950, but rejected it as impractical. It would be far worse today.
    1
  631. LesB SoCal — You don’t put the rod in a handfull of dirt. You use a long rod and drive it deep. Your experiment should be done by measuring the resistance between two ground rods driven into the Eartn near each other.
    1
  632. Zach Prewett — It would not meet US codes. If you are willing to violate codes, you can do anything. I don’t recommend that. Why wouldn’t you just use a US 240V plug instead?
    1
  633. The distribution grid is on the order of 10,000 volts. You use whatever transformer you need to get the voltage you need.
    1
  634. The terminology we use is "grid" means the distribution network, which might cover an entire small city. The drop from the distribution grid to a customer is typically 120/240v split phase, but there are other possibilities.
    1
  635. H2Obsession — I’m guessing there is a real problem which needs to be fixed.
    1
  636. We use a 240V 50A circuit for electric ranges in North America. That’s enough. It is power that cooks, not voltage. If you can’t get enough power from 240V service, you can get a different service. Residential kitchens don’t need more power than is commonly available. Commercial kitchens get whatever they need.
    1
  637.  @DukeSaiko  — You don’t think 12KW is enough to cook with? Some people who comment here are surprised at the anount of power this gentleman’s panel supports. I don’t know what you mean by “devaluation” in this context.
    1
  638.  @DukeSaiko  — As I wrote, it is power, not voltage, that cooks. A typical induction element for a stovetop is 3KW max, so you could run four elements at max on a 240V 50A circuit in the USA. In countries with 240V service minimum, you may not have 50A circuits, because you can get higher power from the phase-to-phase voltage of about 400V from your 3-phase service. In any case, we also have 3-phase service available in the USA, with higher power available, we just don’t make everybody get it.
    1
  639. mark whitehead — There are a lot of cheap and worn-out receptacles in the USA, because the cheapest brand is the one most widely available. I have new Eagles in my kitchen and they grip well. But not so tight that plugs are difficult to pull out. The flat prongs are better for making good contact. The inventor started with round pins, then changed to flat for that reason. Arcing is not a significant problem at 120V.
    1
  640. I learned E = I x R. Are you just quibbling about notation?
    1
  641. When there are three phases in the distribution system in a Y configuration, one phase and the common will connect to the primary of a single-phase transformer. The common is connected to Earth as well. In the photo shown, there is only one phase plus the common, presumably because his location is at the end of a run and he only uses one phase. The common line, which comes to the pole just below the transformer, is connected to the center terminal on the side of the transformer, and to Earth at the base of the pole. The transformer case is also connected to Earth. His drawing which follows seems to show the transformer primary connected to two phases instead of phase-to-Earth, so he doesn’t show the primary connected to Earth on one end.
    1
  642. Mr Glide — No. Why would we do that? Most US buildings fall entirely within the United States. It is not an international matter. Having old wiring and new wiring use different conventions would be a hot mess. If a European electrician comes to the United States and wants to be licensed here, learning the color code would be one of the easiest parts of his reeducation. If he has trouble with that, how did he get to be an electrician? Why are Europeans always trying to tell us how conduct our own affairs?
    1
  643. Sergiu Ionescu — The transformers aren’t usually individual. They can supply two or three households easily. The US system does need more final transformers because of the lower service voltage, but they are less expensive than a transformer serving an entire city block. Everything is a tradeoff.
    1
  644. Steve White — That’s wrong. The neutral always appears “dead” only because it is held at ground potential.
    1
  645. In the USA, a sauna for a single-family home will usually run on 240V.
    1
  646. Perhaps — The frequency must be high enough to give steady light from an incandscent lamp, but not so high as to make the generation difficult. They chose what seemed to be a good compromise.
    1
  647. Jared Prymont — California is land of fires. Some wildfires recently seem to have been started by arcs from poorly maintained distribution equipment combined with dry brush. It isn’t a problem everywhere.
    1
  648. In the US, residential service is single-phase 240V, with split-phase providing two 120V buses in opposite phase. An electric range is typically on a 50A circuit, which would allow a maximum power of 12KW. Most ranges for home use are probably not capable of that power, and it would be unusual to run everything on the highest setting anyway. Most home workshops would use ordinary single-phase service, but someone with a large shop could get 3-phase service if he wanted it. A heavy duty table saw with a 5HP 220V motor draws only about 4000 watts. In a home workshop, you wouldn’t have all the tools running at once. A commercial workshop would probably get 3-phase service and as much power capacity as was needed.
    1
  649. Scott Dean — My condo building has three-phase, so, for example, the elevator has a three-phase motor. Also the motor on the garage door is three-phase. My apartment is on a single phase, but there are no large motors in my apartment.
    1
  650. Help with what? Sleeves would interfere with making a good connection. That sort of thing has to be designed into a system from the start. Now that we have ground fault detection devices, and increased mandates for their use, there is no need for such things. An ordinary US 120V plug is inexpensive and works well.
    1
  651. I learned E = IR.
    1
  652. Roy Marable — What you call a “power meter” actually meters energy, which is power integrated over time. However it works, it gets the right answer.
    1
  653. Tuomas Levoniemi — We have underground wires in some places. Somebody has to pay for it.
    1
  654. Nick Akers — Which nation are you referring to?
    1
  655. anon — I’ve used European plugs recently, and I think exactly the opposite. Our US plugs suit our system, even though they wouldn’t do for yours.
    1
  656. Arguing about nomenclature is pointless. It is what it is. I call it 120-240 3-wire split phase, but you may call it what you please.
    1
  657. No, the amps depend on the voltage and the resistance of the load. You had better not be drawing the maximum amps on either circuit when you are shocked. The modern way to protect yourself from electrocution is with a fast-acting ground fault circuit interrupter built into the circuit breaker.
    1
  658. usquanigo — Agreed.
    1
  659. This isn't about comparing numbers with Europeans. It's just about explaining how split phase power works.
    1
  660. Vivisect — It’s a joke.
    1
  661. Thunder-FoX — That’s what I would expect, but if you had a shop attached to your house that needed motors, could you use 3-phase 400V motors?
    1
  662. It is just another way of looking at things, a distinction without a difference.
    1
  663. SeanBZA — We (in the US) can put protection in the form of GFCI and AFCI on all our circuits if we wish.
    1
  664. Siemens makes panels and breakers for the North American market, so not all Germans have your problem.
    1
  665.  @tobiweinmann3790 — The bare copper wires are grounds, which are connected to Earth. There is no reason to insulate them. I wouldn’t put them on the same bus bar with neutrals, though.
    1
  666. Andrew P — Yes
    1
  667. Roberto R. MOLA — Yes. A US plug feels a lot more secure when it’s in place.
    1
  668. On the contrary, customers can get 277/480 4-wire 3-phase. It just isn’t used for residential service.
    1
  669. We have 480v 3-phase power in the United States. It is used to power elevators in commercial buildings and for other commercial and industrial purposes. We don't need 480v to charge our cell phones or for any other purpose in a residence.
    1
  670.  @pleappleappleap — So? There is nothing that is done in a residence that requires 400+ volts, or 3-phase, for that matter. If you wanted 3-phase in your residence in the US, you could get it.
    1
  671. Hans Wurst — We love standards. That’s why we have so many of them.
    1
  672. djlapio93litlebro — No. Neutral is not hot by definition. Neutral is held at ground potential.
    1
  673. That’s why you should have ground-fault circuit interrupters.
    1
  674. Patrick Harenberg — E = IR to me.
    1
  675. I don’t believe it. Why don’t you demonstrate it for us?
    1
  676. StevenC777 — Nevertheless, it originates from our 60 Hz power system, so it is called “60 cycle hum.”
    1
  677. It isn't more efficient, though. Awhile back, I was looking at electric motors, which often can be configured for different voltages. The manufacturer said there was no difference in efficiency between 120 and 240 volts. You use what you have available. In high power situations you might use 240v to allow the use of smaller wires. In any industrial setting, you use whatever you need. For computers specifically, in the mainframe era you used a motor generator driven by 3-phase power. I don't know the typical voltage, though, because there are a few choices. Who knows what large arrays of rack-mounted computers use? It could be 240v or something else. It doesn't much matter.
    1
  678. The box is connected to Earth.
    1
  679. GBlade Warrior — Since electrocution is fatal by definition, that would be difficult.
    1
  680. dr07828 — Where is it it wrong? Please give the time.
    1
  681. No, it would be complicated and expensive. A huge nuisance for no good reason.
    1
  682. John Doe — Ground fault detection is the single most important thing that makes a system safe, but I have two questions: 1. Did it become mandatory for all old work to be updated to include a new main breaker? Were there cases where the old panel was obsolete and a leak detecting main breaker was not available? What then? 2. When the main breaker trips, all the lights go out. Doesn’t that make it difficult to find the circuit that had the fault? Even with lights, it would be difficult if there were a lot of circuits. Why not fault detection on individual circuits? (I know, that’s five questions.)
    1
  683. utetrahemicon — I have never heard it called an Edison plug, but Edison does get credit for the screw base on common lamps.
    1
  684. orion1820 — Yes, we commonly use RMS when discussing AC power.
    1
  685. It is what it is. A picture is better than words.
    1
  686. Hardly any electrical devices a hundred years old are still in use. That's not a reason to change the power system.
    1
  687. Vega 128 — We do, if you need it. Ordinary households don’t need it.
    1
  688. 2) The customer is charged for the energy used, however it is connected. 3) The benefit for the building owner is that there is less wiring and fixtures to pay for. That is not a benefit to the dweller.
    1
  689. We use several voltages in the United States: 120, 208, 240, 277, 480.
    1
  690. When AC power was developed by Westinghouse, that was found to be the best compromise of practicality and efficiency.
    1
  691.  @billelkins994  — The reason 50 Hz is used in Europe is that the number 60 offended their metric sensibilities. They couldn’t use 100 Hz for practical reasons, so they used 50. Dumb reason, but true.
    1
  692. That is an argument for pedants. The split phase system is derived from a single phase of the 3-phase distribution network, but the output can be considered to be two phases 180° apart. The two views are mathematically and functionally equivalent, so the argument is only about terminology. Pedantry.
    1
  693. That depends on perspective. In North America, we consider Great Britain and Ireland part of Europe.
    1
  694. The first power systems in the US were 110V, chosen by Edison for his DC system. The first Westinghouse AC system was also 110V (RMS) for compatibility with Edison lamps. Eventually, it was boosted to 110-120VAC. When higher voltage was needed, the split phase scheme was chosen because it was upwards compatible with the installed system. It also has the safety advantage that it remains 120V to ground in residential applications.
    1
  695. canadianbacon0 — I’m more than twice as old and have been shocked using an American plug. All this whinging about our plugs is ridiculous.
    1
  696. JAK — We have 480/277 3-phase and some other unusual options.
    1
  697. We are 120/240 vac 3-wire for residential service.
    1
  698. Kai Nikulainen — We get one phase for household use. Three-phase is available in some areas.
    1
  699. Right. Nobody gets shocked using the plugs. It is necessary to protect children. In the old days, we just put plastic plugs in the receptacles. Then we got receptacles with built-in shutters. The modern way is just to have a GFCI breaker on every circuit.
    1
  700. He isn’t trying to confuse people. He’s trying to explain the details to people who are interested. Those who aren’t won’t be watching videos about electrical systems.
    1
  701. Patrick Jackson — I have to tell you that Americans don’t give a fig what Europeans think about the way we do things. Remember, AC power was invented in the United States by Nikola Tesla, an immigrant from Europe. We were glad to have him. His invention helped industrialize the United States and the world.
    1
  702. Steven Ruhl — I have never thought of the knob and tube system as a nightmare. It is obsolete, but only for economic reasons. It was well suited for the time it was used.
    1
  703. No, the neutral was there long before the GFCI was introduced. It is a part of the circuit held at ground potential.
    1
  704. We would have to put in a proper 240V outlet, i.e. one recognized by our codes. If I wanted to boil water faster, I would put in a 240V receptacle and get a commercial induction unit. That would be more versatile. I don’t understand the fondness for electric kettles.
    1
  705.  @tallswede80  — I don’t care for microwaves.
    1
  706.  @tallswede80  — Only that a 120V unit is limited to 1800W.
    1
  707. Yes, 480/277 4-wire is available in some places.
    1
  708. KD Puvvadi — The US distribution grid is also 3-phase. The final transformer delivers single-phase power to the customer.
    1
  709.  @gamecubeplayer  — Yes, I took my iPad to Europe and just plugged it in with an adapter.
    1
  710. Jason Knight — That was my thought when I first read the posts on kettles. I have a kettle. I heat it on my gas range.
    1
  711. If every outlet were 240v, my coffee maker wouldn’t work. I couldn’t have that.
    1
  712. Helge Träm — Yet you don’t want nuclear power plants to keep all those circuits humming?
    1
  713. It is mathematically equivalent — just two ways of looking at the same thing. It is a controversy only for pedants.
    1
  714. We call them Ground Fault Circuit Interrupters (GFCI).
    1
  715. If you have a 3-phase Y service with 120 vac on each leg to neutral, then phase to phase is 208 vac.
    1
  716. spaceduck413 — Keep in mind, these are people who don’t know what an inch is.
    1
  717. Color code conventions are arbitrary. Every US electrician knows our conventions.
    1
  718. Paul Moir — It would have made it expensive, not impossible, but that’s a good point. Rural electrification was a big deal in the 1930s.
    1
  719. It is 400 vac because it is 3-phase, just as drawn here for 120/208 vac. But yours should be 230/400 or 240/416.
    1
  720. aullik — Yes, we have 3-phase. The entire transmission and distribution systems are 3-phase. If you want 3-phase in your home, you can get it.
    1
  721. Paul S — Faux grounded outlets are a problem. Often, new wiring is required to get a proper ground.
    1
  722. teslapower220 — Good point.
    1
  723. You mean Residual Current Device, I suppose. In the US, we generally do that circuit-by-circuit, either with a special receptacle or in the circuit breaker.
    1
  724. Pandu Poluan — We are doing very well with our customary plugs, thank you.
    1
  725. I don’t know what you mean “dodgy.” I’ve used European plugs and I like North American plugs better. Outlets behind a sofa are a problem. Blame it on the builder, not the electrical system. When one has an outlet which is obstructed in that way, the thing to do is use an extension cord to bring the connection point to the end of the sofa. I have some cords with a right-angle plug which are useful for that purpose.
    1
  726.  @LondonSteveLee  — Never in my long life have I done that or known anyone to do that. The hazard is greatly exaggerated.
    1
  727. Dave Johnston — Nobody actually gets shocked that way.
    1
  728. John King — This is baloney. Distribution networks in the US operate at 2300Vac or more. Transformers step the voltage down to whatever is needed by the end users. Whether the transformer is on a pole, at street level, or underground is just a matter of whether someone is willing to pay more.
    1
  729. Distribution is always done at several thousand volts.
    1
  730. There will typically be two or three receptacles on one 20A circuit. If you had several appliances which actually drew close to 20A, you would be tripping the circuit breaker every time you tried to use two of them at on e.
    1
  731. Ethereal Rose — I don’t think you are giving Michael Faraday (and others) enough credit. And Nikola Tesla came to the United States from Europe, of course. Other Europeans contributed to AC power development, but they aren’t as well known as Tesla.
    1
  732. David Thatcher — We don’t “ground to neutral,” but we tie neutral to ground. That’s the right way to look at it.
    1
  733. Kellen Green — The US is starting to require those also. I hate them.
    1
  734. This panel looks wrong to me. He seems to have put ground wires into the neutral bus bars. I don’t even see a ground bus bar, which comes as a separate kit. Even though the neutral is bonded to ground, because it is a main panel, that does not mean you should mix the grounds in with neutrals on the neutral bus bar. Bur I’m not an electrician. If there are any U. S. licensed electricians reading this, I’d like to read your opinion. Edit: Apparently, using the neutral bar for grounds is allowed in a main panel with the neutral bonded to the case. That explains why the ground bar is an optional kit.
    1
  735. Most electrocutions in the US are of people trying to work on an appliance without unplugging it. The next largest category is of people using an aluminum ladder near power lines.
    1
  736. By the way, electrocution is fatal by definition.
    1
  737. SublimeSparo — If a tea drinker found himself (or herself) confined to the USA, I suppose a 240V outlet could be installed in the kitchen for use for an electric kettle. But when I look at 240V kettles, they are described as being for 50 Hz, not 50/60 Hz, and “not for USA.” Deos that matter? What happens if you give it 60 Hz power? The way I would do it is to use a 240V induction unit on the outlet and a nonelectric kettle. Then I could use it to boil water for pasta as well.
    1
  738. It is easy to install a switched outlet in a US system. We would just use a combination outlet and switch device in place of a duplex outlet.
    1
  739. If you want uniformity, change your own system. Ours works for us.
    1
  740. The US electrical system was developed by Westinghouse. Tesla worked for Westinghouse.
    1
  741. That’s exactly right. Our system was an upward-compatible expansion of electrical service.
    1
  742. Why what? We distribute electricity to homes to have electric lights, hot water, a laundry, etc.
    1
  743. D. Lindvall — It was called out a few times.
    1
  744. On the low side, I think.
    1
  745. It actually evolved the other way around, though. The 120v service came first, then the 3-wire system was developed in order to get 240v while retaining compatibility with 120v.
    1
  746.  @SixStringViolence  — I am aware of the role of the Soviets. My point is that our electrical system has evolved from the very beginning of AC power. There are historical reasons for our use of 120V, and for the particular form our electric equipment takes. We (in the USA) have never had a need to do a general rebuilding of infrastructure, so naturally give importance to upward compatibility. The split-phase architecture in particular was an ingenious method for increasing voltage in an upward-compatible way. We do have modern safety features of ground fault and arc fault detection, which are the main things. Euro-style in our breaker panels doesn’t do anything for us. The equipment is normally covered up and out of sight. What I see in the design of our electrical service is practical engineering in practice. It has lasted for more than a century without fundamental redesign (the major change would be from fuses to circuit breakers) because it was well-designed from the beginning. Hubbell’s first plug and receptacle was invented in 1904, and the flat blade style was introduced about a decade later. It became the standard for 120V circuits ever since because it is well-designed.
    1
  747. Martynas Stanaitis — A GFCI breaker is the same size as a standard breaker in most brands of load center.
    1
  748. Mr. Niu Si — The best for our purposes, anyway.
    1
  749. I don’t know what you mean by “markings.” Any color-code convention will be confusing if it differs from what is familiar. One must just learn the convention for whatever system one is faced with.
    1
  750. ShadowDrakken — Cheap power supplies. Computers should protect themselves from line power.
    1
  751. I like our North American plugs and receptacles. The reason they have lasted a hundred years is that they are inexpensive and effective. They have undergone improvement in that time, of course. Modern molded plugs are better than the old-fashioned ones that were hand wired.
    1
  752. cjeam — Don’t go grabbing the wires! We install a 240V circuit where we need it, such as for a clothes dryer, then we just use it. No fiddling with wires needed. The dryer stays plugged in all the time. If you want to remove power to the dryer, you trip the circuit breaker.
    1
  753. Konve — This gentleman has a panel with a large number of breaker positions. His main breaker was installed at the factory and sized for the load one put on such a large panel. It is unusual for a single dwelling to have so many circuits.
    1
  754. Villipend — I’ve never even been shocked doing that, and I’m an old guy.
    1
  755. No, 208V is only found in certain 3-phase systems.
    1
  756. There are not many homes in the US without 240V today. I’m surprised a house built in 1948 wouldn’t have it.
    1
  757. Be serious.
    1
  758. Mr Skeedle — Baloney, in my opinion.
    1
  759. I don’t know what you mean “lowered the entrance,” but the plugs work well as they are now, and we would not want any redesign which was not compatible with existing equipment. The most prevalent problem we have with our 120V connections is with cheap or worn-out (probably both) receptacles which don’t grip the prongs snugly.
    1
  760. We have 3-wire service in the US, normally. Your last statement is unclear.
    1
  761. clitiss wood — I take it the European system has fewer final transformers than the US system, which would be less expensive. But when a transformer fails, it would cut power to more households. Whether the transformer is on a pole or underground is an entirely separate question. The reason we (in the USA) have a lot of wiring on poles is that the end users have to agree to pay to put the wiring underground.
    1
  762. He is showing it without the cove. Normally, it is covered unless working on something in it.
    1
  763. Dick Biggles — Surface oxidation on a ground wire doesn’t matter. It’s a heavy wire and it’s clamped in place when clean. If properly installed, it will do its job for a very long time even if there is some surface corrosion. As for using copper, what is the diameter of wire used for common circuits in countries that use 240V?
    1
  764. B. SERVICE DELIVERY VOLTAGES (PG&E) 1. Following are the standard service voltages normally available, although not all of them are or can be made available at each service delivery point: Single-phase Secondary 120/240, 3-wire 120/208, 3-wire Three-phase Secondary 240/120, 4-wire 240, 3-wire* 208Y/120, 4-wire 480/3-wire** 480/277, 4-wire 480Y/277, 4-wire
    1
  765. J Dietrich — There is no question about that not being the most important safety factor. They would probably have prevented most electrocutions in the US. We have them, but we only install them on new circuits as a rule. When they are optional, not so much.
    1
  766. jan feijes — In the US, grounf fault protection is contained in a breaker for a circuit, or combined with a receptacle. They are most often seen only on kitchen, bathroom, and laundry circuits.
    1
  767. Derrick Willmott — The problem with lamps is that a lot of them are cheaply made and poorly maintained. Some are even homemade. Even if the metal were grounded, the ground wire could come loose as easily as any other. A better solution, in my opinion, is to require a GFCI on every outlet circuit. The problem there is that it only applies to new work.
    1
  768. noname-cv37 — We generally do not have 240V circuits everywhere. We would have to add circuits, so the expense and trouble would be too high. I have a European refrigerator, which of course has been Americanized. European manufacturers know how to do that.
    1
  769. steven hughes — Hospitals have their own convention. It isn’t a rule. I prefer the ground at the bottom.
    1
  770. ROHIT KUMAR YADAV — To whom are you addressing the question? American electrical service has a neutral.
    1
  771. Everybody knows that. So what? You don't need 400V to charge your cell phone. We (in the USA) have 400V (480, actually) where we need it, not in people's homes.
    1
  772. Herr Bönk — Transmission and distribution lines are 3-phase.
    1
  773. alan dawson — In my long life I have never heard of anyone getting shocked in that way. Of course, one must look after small children and child-proof any room where they play unsupervised. There are greater hazards to children than elctricity. Besids, ground fault detection is an easier way to make any circuit safe.
    1
  774. There is an inductive coupling from the mains to the meter. It’s a transformer. Edit: Do you mean his multimeter? That’s different. The mains current doesn’t go through it. I was referring to the power company meter.
    1
  775. I think one 240v receptacle in a kitchen would be useful, for heating large amounts of water, but there aren't any household devices to use it. A commercial induction heater would be one possibility. Heating appliances like cooking ranges, water heaters, and clothes dryers are 240v.
    1
  776. No.
    1
  777. The skin effect is frequency dependent. At 60 Hz, it is not significant.
    1
  778. Slim Tony — It would make more sense to use a U. S. approved plug on a European appliance. Better yet, just use an adapter. I use an adapter when I travel to Europe.
    1
  779. Absolute Genius — We have tamper-proof receptacles. It isn’t that complicated.
    1
  780. With phases being 230V to neutral, it should be 400V phase to phase.
    1
  781. PRIZ ;] — Ok, but are they 12-slot panels or 36-slot panels?
    1
  782. So you can tell they are ground wires. Why insulate a ground wire?
    1
  783. LaLaLand — We (in the US) know how to put wires underground. The poles aren’t inherent in the system, just cost-effective.
    1
  784. Bill Elkins — Why would a teakettle use 3-phase power?
    1
  785. taiiat — I think such plugs have an insulating sheath around a metal pin.
    1
  786. There is a cover for the entire box, which he will no doubt install when he is done working in it.
    1
  787. Justin Giffard — No.
    1
  788. We are safe. People who get electrocuted are generally trying to repair an appliance without unplugging it. Another popular way to get electrocuted is to stick a metal ladder into overhead power lines. Nobody gets electrocuted just plugging in a lamp.
    1
  789. David Marsh — Completely wrong! The US household power of 120Vac is 120 RMS between the hot and neutral wires. For a sinusoidal wave, RMS is .707 of the peak voltage, which would be 169V. Peak-to-peak is twice that.
    1
  790. Cody Konior — In the US, a homeowner may work on his own electrical system, subject to getting a permit and having the work inspected. You need a license to work on property not your own, or on property rented by others.
    1
  791. Because there is no point, I suppose. We have a device which combines a switch with a single receptacle which fits in the space of a duplex receptacle. The switch can be wired to control the power to the receptacle. They aren’t common, though. Why would I want that? As someone here has noted, we sometimes have a switch where light switches are placed used to control a receptacle for a lamp. Such a switch might control all the upper half of duplex outlets in a room.
    1
  792. Fredrik Angell Moe — Are you saying the homes get all three phases, or only one of the three?
    1
  793. S J — You need to ask the manufacturer of the tool whether it is compatible.
    1
  794. It is more efficient to transmit electrical power at higher voltage.
    1
  795. Martin Pollard — I don’t know what you mean “proper.” In the US, our electric systems are grounded to earth. You should be able to ground the chassis of an electric range by just connecting it with a wire to the outlet box.
    1
  796.  @Velez0777  — Your appliance is not typical, then.
    1
  797. MLTatSea — Some people think the ground pin should be at the top but I like it at the bottom. Because others have also said it should be at the top, I did a little research. The Cooper website (I like their Eagles) shows them with the ground at the top. Then I watched a Leviton video (I hate their stuff). They showed how to wire an outlet and put the grounds at the bottom. Then they said you can orient it either way, or sideways. I just finished an electrical project. My licensed electrician put the grounds at the bottom. My inspector had nothing to say on the matter. I will continue to prefer the ground at the six-o’clock position.
    1
  798. justunicorn001 — That’s a stretch. There is nothing to figure out. For one thing, the receptacles are different. You can’t put a 120V plug in a 240V socket. For another, in most homes there are only a few 240V connections and they are in out-of-the-way places. As a practical matter, everything accessible is 120V. By the way, we do deliver power to multiple outlets. That has nothing to do with voltage.
    1
  799. Chris L — We can do that where it is needed, but households do not need polyphase power.
    1
  800. Alan Rose — The bare wires are grounds. There is no reason to insulate them inside a panel.
    1
  801. AM — E is voltage. I is amperage. They are proportional in a resistive circuit.
    1
  802. Resin Boi — Nobody gets a shock from a loose plug. I’ve never heard of it. This is an imaginary hazard.
    1
  803. Lucas 'Ktulu789' — So if you have one GFCI for the whole house, and somewhere there is a loose wire which trips the breaker. The whole house goes dark. Maybe its in the evening, so quite dark. How do you find the circuit with the fault in the dark?
    1
  804. 4IN14094 — That is one way to look at it, but you must add that the phase angle is 180°.
    1
  805. Alex Paulsen — That’s baloney.
    1
  806. Chris Ridout — The main “fuse” is the main breaker at the top of the breaker box, which shuts everything off. The power company might have a fuse at the transformer.
    1
  807. Zenn Exile — We used to have 440 yard races, but track is all metric now.
    1
  808. If you had 240 VAC phase to neutral, it would be 416 VAC between phases. Three-phase systems in the USA are usually 120/208 or 277/480.
    1
  809. At 120V, arcing is not a serious problem.
    1
  810. An A/C is usually 240V, in which case the receptacle type should be different.
    1