Comments by "GH1618" (@GH-oi2jf) on "The Engineering Mindset" channel.

  1. The neutral is always at ground potential, but current flows both ways. The flow changes direction 100 times per second (50 Hz) or 120 times per second (60 Hz).
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  2. In a simple case of a constant resistive load, amperage is proportional to voltage.
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  3. We measure voltage with a high-impedance circuit through the meter such that the current through it is so small that we can disregard it.
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  4. The neutral is tied to Earth, so it should always have a low potential relative to Earth regardless of current flowing on the neutral.
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  5.  @ChickenPermissionOG  — Your original comment did not say you had a fault. Of course when there is a fault, strange things can happen. If there is a dead short to neutral, then a circuit breaker should have tripped. Why didn’t that happen? You should not assume any wire is safe without testing.
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  6. No. The “neutral” wire is tied to ground; the “hot” wires are not. Current has nothing to do with it.
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  7. No. “Hot” means that there is a potential difference (voltage) with respect to ground. Direction of flow is irrelevant.
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  8. M — They should be the same, except for color.
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  9. Charles Xavier — Forget about phase for a moment. Ignore the center tap. Then it’s a simple transformer with a 240V secondary. Adding a center tap allows you to use the secondary as if it were two 120V transformers.
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  10. We (in the USA) put those on the individual circuits. If you put it on the main breaker, then when it trips, everything will go off.
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  11. Skyler Holman — I don’t see why you think it is expensive. A center-tapped secondary doesn’t cost much more. The 120V receptacles are inexpensive, even for the heavy duty grade that I buy. Where do you see unusual expense?
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  12. Every wire has some resistance. Load has nothing to do with it. We commonly say resistance instead of “resistivity.”
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  13.  @andreasolin8520  — The wire is just part of the load, but an insignificant part, normally. We (in the USA) seldom worry about the resistance of the wire. We think about the maximum current and the code requirement. For example, for a common 20A circuit with receptacles we use #12 solid copper wire.
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  14. That diagram is not helpful, in my opinion. “Neutral” is term generally used in AC circuits, and the neutral is grounded. There is no ground in that illustration. If you want to understand AC electricity, I recommend you disregard any illustration with a battery in it.
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  15. Earth ground is important. If you get a shock because of lack of a ground, it’s no laughing matter.
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  16. MrJohnisthename — The wider side is the neutral. It was introduced because of the recognized weakness of the Edison screw base used on ordinary lamps. It is much easier to accidentally make contact with the threaded part of the lamp socket than with the button in the senter. For that reason, when you wire a lamp, you must use a polarized plug and make sure that the neutral side of the plug is connected to the threaded contact in the lamp socket. Lamp cord contains two kinds of wire to help you do this.
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  17. There is not one standard voltage because only the power company is concerned with that. It could be from a few thousand volts to 20,000.
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  18. Appregator — So?
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  19. This is the North American system, so 60 Hz.
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  20. No. A single phase genrator transmits all of its power over two wires. If you have three such generators offset by 120° you can generate three times the powr and transmit it over only three wires instead of six.
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  21. groove jet — “Conventional current” was defined before atomic structure was understood. When working with electricity at a practical level, it is better not to worry too much about the physics.
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  22. At 1:20 is shown a conversion from the 3-wire delta transmission line to a 4-wire wye distribution line (3 phases + neutral). The neutral should be shown strung below the others. At 1:40 is shown a transformer which takes one phase and neutral to produce the 3-wire split phase service used by most residential customers. All three phases are used by connecting residential customers to any of the three phases, to balance the load.
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  23. manu — It is historical. Electric service started at about 110 volts because that is what worked best for the lamps of the day. The 3-wire system was developed to get a higher voltage while retaining compatibility with existing devices.
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  24. We don’t have one per plug. Ideally we would have one per circuit, but only new construction is likely to have that many.
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  25. Every tangible thing is made of atoms, and every atom has electrons associated with it. The electron is the carrier of negative electric charge. Some electrons are loosely bound to their atoms. When they get loose and move somewhere else, we call that electricity.
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  26. Does the appliance have any 120V components? Better check with a UK electrician.
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  27. Anwon Dells — No.
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  28. Same thing.
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  29. It is easier than that. You are at the right age to start learning practical electricity.
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  30. It is a property of certain subatomic particles. Charged particles act according to Coulomb’s Law.
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  31. You will need tp have the power company disconnect you. They might have to increase the wire size for your service. Write down the plan and run it by your electrical inspector.
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  32. Ignore everything with a battery.
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  33.  @igorivanov7232  — That is a topic in itself which is discussed elsewhere. Neutral and Ground wires differ in that a neutral wire is a normal part of a 120V circuit and it carries the current of the circuit. A ground wire is not a normal part of the circuit. It serves another purpose.
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  34. In cars, we use negative ground, meaning chassis ground. There used to be cars with positive ground. It’s arbitrary, so just a convention for automotive electrics.
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  35. You have to use a GFCI breaker which supplies both circuits.
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  36. In the US, they should both be black.
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  37. You need two bars to have enough positions for a fully populated box. If you use the box as a subpanel, the grounds and neutrals must be separated.
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  38. Doesn’t matter. The housing of US plugs is not standardized, so he can make one which looks British if he likes.
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  39. Yilun Mao — The neutral should be grounded at the pole.
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  40. Neutral and ground are bonded only at the point of main disconnect. If that is the main breaker panel, grounds and neutrals may be connected to the same bus bar, but that must not be done in a subpanel. It is better practice to keep them separated on their respective bus bars, in my opinion.
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  41. Newer what?
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  42. That is correct for “conventional” current. The early scientists who studied electricity named it before the electron was discovered and understood.
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  43. While the distribution system is 3-phase, a transformer for normal residential service is connected to only one phase. The secondary is 240V. The transformer produces two phases in the secondary by means of a center tap. The two ends of the secondary are 120V relative to the center tap and in opposite phase.
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  44. Cal — Electrocution is fatal by definition.
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  45. You are charged for energy, which is the product of voltage and amperage, integrated over time. The electrons aren’t consumed, but they are pushed back and forth in the wires. In the process, they do work. You are charged for the work, which is energy.
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  46. In a properly wired and maintained system, the neutral will always be at or near ground potential, so it is safe. The metal breaker box is connected to the service neutral and to ground.
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  47. No, it is just electrons per second.
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  48. The transformer takes power from a single phase of the 3-phase distribution network and delivers 240V AC across L1 and L2. That is single-phase AC. The polarity of AC changes 120 times per second. At any instant in time (except at the zero point) L1 and L2 will have opposite polarity.
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  49. Heat blows the fuse, but everything is related. The fuse has a carefully calibrated resistance. As the resistance of the load decreases (by adding more lamps in parallel), the current of the whole circuit increases and the voltage drop across the fuse increases (because it becomes a larger fraction of the circuit resistance). But it is the current in the resistance of the fuse that generates heat according to the I^2 * R rule.
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  50. This presentation seems better than a previous one, except at 2:26 there is an attempt to illustrate currents. It shows current flowing out of the two “hots” and returning through the neutral. This is wrong and I think you know it is wrong but are trying to simplify the description. I think it is more likely to confuse those who don’t quite get it. The correct view is that the flow on the “hot” lines (L1 and L2) must be in opposite directions. There are three circuits: 1. 240V through L1 and L2 2. 120V through L1 and N 3. 120V through L2 and N The direction of flow must always be opposite at L1 and L2. The currents are summed. The direction of flow on N depends on how the currents add.
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