Comments by "Jovet" (@jovetj) on "Ground Neutral and Hot wires explained - electrical engineering grounding ground fault" video.

  1. The only other thing to add might be the professional trade/code difference between grounded conductor and grounding conductor.
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  2. @Ironbuket In typical DC wiring, yes, Red is (+) and Black is (–). In most automobiles, the frame (or frame ground) is negative. There is no neutral, but there could be if you connected two batteries or cells in series and had a third connection between them (e.g. here the + and – are connected). Electrons are negatively charged, so they are drawn to the positive terminal. May be weird to think about at first, but it's accurate. With AC, there is no polarity, so (+) and (–) doesn't apply. Thus, wiring colors are pretty arbitrary. In North America, any wire color that is not white, gray, green, or bare should be considered a Hot. And a "hot" conductor is one that is not grounded. If it's grounded, then it is conducting current in the circuit, but it also is at the same voltage potential as the Earth.
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  3. The neutral and the hot do not switch places. A "hot" wire is a conductor that is not grounded. Most neutrals are grounded. In AC, the polarity of the circuit is constantly fluctuating. One moment, the "hot" is (+) and the neutral is (–). The next moment, the "hot" is (–) and now the neutral is (+). And then, the next moment, they've flipped back again. This happens constantly. Because the neutral is connected to ground, the neutral and ground are at the same voltage potential no matter what polarity is active. Once a circuit is turned off, no power flows at all. Not through the hot, and not through the neutral of that circuit.
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  4. That part of the video is a bit confusing, because you're right. Most automobile systems in North America are negative-ground. (Also keep in mind that this is FRAME ground, and not EARTH ground.) The video does correctly depict electrons moving from the negative to the positive terminal, however. I think the video is trying to make a comparison to from the simplicity of a battery to the way a circuit in a home is setup, but it fails with the nuances of DC polarity.
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  5. A "Hot" or "live" wire is a conductor that isn't grounded. That can be earth ground, or frame/chassis ground. The term "hot" is not usually used with isolated DC circuits, although it can be.    The majority of direct current (DC) systems people are familiar with are (–) ground, but (+)-ground systems exist, too. It doesn't really matter, as long as it's known and consistent within a system. Polarity matters in DC.    Alternating current (AC) does not have static polarity, so the idea of (+) and (–) doesn't apply. Either a conductor is grounded, or it isn't. Remember that electricity only flows in a complete loop, called a circuit. If there is no complete loop, then electricity will not flow. DC always flows in a persistent direction, but AC changes back and forth (alternates polarity) and this happens throughout the entire circuit (not just the "hot wire").     Atoms cannot get a "surplus of protons." Atoms want to be neutral, which means a balance of protons (+) and electrons (—). Atoms can become unbalanced by temporarily losing or gaining electrons, and such atoms are called ions. Atoms can only gain protons by nuclear fusion, which is what happens in the core of the Sun, or nuclear decay.  "Hot" or "live" conductors are special only because they are the parts of the circuit which are isolated from the grounded path. There is no voltage potential between the grounded conductor and the ground system itself because they're connected together. The "hot" or "live" is switched/fused because it's a lot easier to further isolate what is already isolated. Plus, it reduces further problems and dangers of accidentally interrupted neutrals. Not all AC circuits have a "neutral" as that really derives from the middle tap of a secondary winding on a transformer. A power source works by inducing a voltage potential in a conductor through a complete circuit. On a battery, the positive terminal isn't more or less "active" than the negative terminal. The two terminals just have opposite roles. One is going to accept electrons, and the other is going to donate them. 9V or -9V is still 9 volts of potential, no matter how you measure it. No one terminal of a power source is "more important" than another, because there still has to be a loop.
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  6. @kal9001 Yep. Much safer to have a carefully-controlled "hot" and assume everything else is the same potential (ground, or negative). @Pqrst Zxerty Most general DC power source wiring is red and black, so by that logic, the white wire should be black, too. But, remember, that (+) is only the red wire in (–) ground systems. In reality, the black wire represents (chassis) ground, and the red wire represents not-ground. So, in a (+)-ground system, the (+) would be the black wire. So, the video is more-correct on that point, even if it's just something most people are not used to. Excepting it's a white wire, not black. I think it would be less confusing if the (+) and red/black wires were employed as usual, and the current was still just shown to flow (–) to (+).
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  7.  @DeepCZero3  Positive grounds are still around in the telecommunications industry as well.
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  8. Static electricity doesn't work the same as the electricity we generate with batteries and power plants. It's still a "flow of electrons" but that's about all they have in common. When you use a power source, you're setting up a prolonged voltage potential between the terminals on that power source. For example, a 12 volt battery will have a 12 volt difference between the + and – terminals. That difference is maintained as long as the chemicals in the battery can. When you rub a balloon on your hair, you're not creating or using a prolonged power source. You're causing electrons to be casually shed from one object onto another. This happens because all objects are "solid" because electrons (like charges) repel each other. The rubbing increases the chance that this electron-electron interaction will cause some loosely-held electrons to be ejected into the other material. Atoms want to stay neutral, after all, so when those few electrons leave, the atoms left behind become slightly positive. A static electric discharge is simply the return of those extra electrons back to where they belong. As air molecules move around, they rub together, and rub against the Earth, they transfer electrons just like your hair and the balloon do. Lighting is the static discharge between the charged air molecules and the Earth. So, in way, you can think of static electricity as a "flow of electrons back to its source (source atoms)," but it's more of a quick neutralization...not the sustained flow we typically think of as electricity.
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  9. Luckily, with videos on the internet, you can pause them, and re-watch them, at will.
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  10. Really helpful video. Nice visualizations! The only thing I don't like is around 1:47 when you're using terminology of "hot" and "neutral" with regards to a battery source. Since you later touch on the difference between AC and DC, and how the center-tapped neutral works, this seems particularly egregious.
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  11. The "hot" and "neutral" are not swapping places. Remember that a "hot" or "live" wire is a conductor that is not grounded. The neutral is not only the center-tap out of the transformer, but it also is grounded. Remember that a battery has a static polarity. (+) is always positive, and (–) is always negative. The only way to reverse a circuit is to take the battery out and hook it in backwards. But, that is basically what AC does, 50-60 times a second. At one moment of AC, the "hot" may be (+) and the neutral would be (–). A few milliseconds later, the "hot" would then become (–) and the neutral is (+). And a few milliseconds after that, they switch back. The switch back and forth is not instantaneous. If you graph it out, it is a beautiful sine wave. It is not important to know what the polarity of the circuit is, because it doesn't matter—it's constantly changing. It is only important to know which conductors are grounded. And then, if more than one conductor is not grounded, which is which (e.g. multiple phases).
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  12. Watch that segment at 8:16 again. It says the breaker might not trip, not that it definitely will.   The point is that current will travel through the earth, but it doesn't travel nearly as easily as through a fancy copper conductor. Enough current could flow through you to stop your heart, but not be enough current to trip a circuit breaker. How much current can flow through the earth depends on many factors, such as the type of soil, the how far apart the ground rods/connections are, the voltage, etc.
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  13.  @robertbrandywine  In essence, there is no difference between the neutral and the hot wires for circuits branching off of the main panel. They are both necessary conductors for a 120V circuit. The only difference between them is the neutral is grounded, and the hot(s) is not. The connections on the transformer, especially the secondary side, are called taps. The neutral is connected to the center tap because it's right in the center of the secondary coil. A 120 volt load is connected to one of the end taps ("hots") and the center tap. This completes a circuit providing 120 volts because we're only using half of the 240 volt secondary coil. (Remember, in a transformer, the number of coils of wire in the coil determines the voltage.) Power flows through the neutral because it is the circuit. It's just as if the rest of the secondary coil isn't there at all—you can pretend it does not exist. A 240V device uses both hots (both end taps) and power flows through both of them because they are both the circuit; the neutral is not used and so no power flows through the neutral for a 240V circuit. The power the neutral actually carries between the transformer and the panel is the imbalance between the load on the two end taps for the sum of all circuits on the panel. Electrically, the two halves of the secondary coil of the transformer are in series to each other. The two halves of the panel are, too; it's just the panel part is a lot more complicated because of all the sub-circuits. I hope you now see that the answer to your last two questions you asked is "yes". Just be sure to avoid phrases like "negative" and "positive" in the AC world.
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  14. The whole reason for the ground wire, and grounding the washing machine frame to it, is so that should the frame become energized, it is able to follow the ground path back to the neutral in the main panel. That completes a low-resistance circuit, allowing much current to flow, quickly tripping the breaker or blowing the fuse.
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  15. 1) The two "hot" wires shown here are still the same phase. 2) The circuits connected between the two hots are essentially connected in series. The neutral to the transformer only carries current when the neutral-hot load of one hot does not match that of the other. There's still no polarity because alternating current. 2) Current will not flow from the neutral to ground because the ground does not complete a circuit, any more than touching a terminal on a battery (and nothing else) causes current to flow into you. See also: birds on a power line. 3) Because the neutral is connected to the ground wire, they are at the same potential. If properly wired, the only time you could get a shock from any grounded metal surface is when a ground fault is in progress. The purpose of the ground wire is to get a large fault current to flow to cause the over-current device (circuit breaker or MCB) to trip quickly. Thus, the chances of actually getting a shock are low, but possible.
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  16. The neutral is connected to ground which allows one of the circuit conductors to be at ground potential. Then, only the non-grounded "hot" or "live" conductor can shock you. We do not use 2-phase here. It's a single phase, usually described as split-phase. Multi-phase installations are rare in residential wiring but are common for farms and industries and other commercial premises. Some three-phase installations can also have a split-phase segment. Running less voltage around most of the house makes it a safer in case of accidental contact. Most service drops into homes are completed with aluminum wire, not copper. Larger cable is needed for aluminum, but it is still cheaper. Solid (rigid) wire is only used for conductors on utility power circuits sized #10 AWG or smaller. It is slightly smaller and provides clean terminations without extras like ferrules. It is generally not difficult to work with solid wire, but there are times when lots of the thicker stuff can try your patience.
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  17. Canadian electrical service and devices are very similar to those in the United States. For most intents and purposes, they're identical. Some of the wire color codes and rules are slightly different, but not much. Multi-phase service to a single or dual-dwelling residence is very rare in the US and Canada. The only exception usually is a farm where multi-phase motors are employed. Three-phase service is very common to farms, and commercial properties, and bulk-residence buildings such as high-rises and the like. Basic residences have no need for multi-phase service.  Single phase service is almost always completed with three wires (for 120/240 volt availability). Some basic service drops such as for a traffic light may only be 120V. Two or three-phase service can be provided through three or four wires, depending on the specific configuration.
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  18. What do you mean?
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  19. But it's still called the neutral.
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  20. I didn't know black and white colorblindness was a thing.
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  21. What happens when you rub a balloon on your hair? It builds up a static charge, and your hair starts to stand up. Lightining is the result of AIR rubbing on the EARTH. The soil is the balloon, and the air molecules are your hair. Once enough charge builds up... ZAP!
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  22. Yes.
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  23. No it is not. The "Hot" and "Neutral" on the battery are misleading and inappropriate, but the current through both wires to and from the light is the same.
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  24. You're right, it doesn't matter, except that the neutral is grounded, and is safer in some situations. A light bulb socket is a great example. An Edison base has the screw shell as one contact and the tip as the other. Normally the tip is "hot" and the screw shell is "neutral." It's easy to touch the screw shell, especially when inserting/removing a bulb, and if this were the "hot" it could be quite a shock. But, since the neutral is grounded, there is little voltage potential to get shocked from.
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  25. Your first paragraph is correct. The neutral essentially does double-duty. Because the voltage and polarity are constantly changing in alternating current, AC current is not as much of a demand on a conductor as DC is. The shared neutral can do double duty because both of the two hot wires are out of phase with each other. Neutral versus ground is not too complicated. The first thing to remember is a circuit does NOT need a ground to work. All circuits are a complete loop, or path from the source, through the loop, and back to the source. AC or DC, makes no difference. All a complete loop. More complex circuits will have many branches and diversions, but it's still a bit loop. No complete loop, no current flows anywhere. You can think of it like the blood vessels in your body. They are just a big, complex loop. The major vessels carry a lot of blood, but they branch into smaller and smaller ones, only to come back together into larger ones and go back to your heart—the power source. This means every basic circuit needs only two wires. One going from the source, and one going back to it. Usually the two wires are kept relatively close to one another, for safety and convenience, but they don't HAVE to be. A while back it was realized that it was safer if one of those wires is connected to the Earth. This eliminates the voltage potential between it and the ground, so it can't shock you. It still carries the same current as part of the circuit, however. But no matter what voltage it's at at that moment, the voltage difference is always the same as the ground, since it's connected to it. That means one of the wires is grounded (or earthed), and the other is ungrounded.  It was then realized that metal chassis and other equipment parts could become the same voltage difference as that other ungrounded conductor when they're not supposed to. If that happens, a person could touch those parts and form a new circuit path through his body and back to the ground or grounded conductor. So, it was decided to connect all those metal parts to each other and the Earth too. That way, if any of those parts got energized, the power would be easily taken down to the earth, back through the ground connection to the grounded conductor, and then back to the source. This would likely cause a short circuit (complete path with little resistance), resulting in a rapid overcurrent and a fuse or circuit breaker blowing. The wire that connects all the metal parts that should never carry current together is called the grounding conductor, or ground. The grounding conductor should never carry current except when something is wrong... and then, ideally, only for a brief period.  The neutral is the common conductor in your first paragraph, which is also grounded. The wire actually connecting it to the ground is the ground wire. The neutral is a required part of the circuit because it normally carries current. The ground carries current only when something is wrong, as a safety feature. Additionally, that neutral is only grounded at one spot: the main disconnect after the transformer. This prevents bad current interplay between the neutral and grounding, system which can happen otherwise. Polarized plugs do not provide a ground connection. Since they have only two prongs, there is no ground prong. Remember, I said above that a ground wire is not required... only the two circuit wires are needed. What polarized plugs do do is make some electrical equipment safer, when it's important that the grounded conductor (the neutral) be connected in certain ways. A lamp is a good example. The screw base of a light bulb socket should always be the grounded neutral, never the "hot" wire. Polarized plugs ensure that's the case.
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  26. Not exactly. One reason is because the neutral is grounded, and the "hot" is not. "Neutral" also refers to a particular position in the scheme of the power source. For Y three-phase, it's the conductor common to half of all the phases. For North American split phase, it's the center tap of the one phase transformer. Both the hot and neutral are carrying the same load (depending on the circuit topology and location in the circuit) so are otherwise the same.
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  27. The demonstration with the battery is inappropriate, so don't worry about it. DC circuits don't really have a "neutral" and a "hot" or "live" wire is any conductor that is not grounded. The battery diagram was an attempt to relate the simplicity of a simple battery & lamp circuit to that of a home circuit.
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  28. GFCIs/RCDs don't care about the ground wire. All they do is monitor how much current is flowing through both the regular wires. Because electricity always flows in a closed loop called a circuit, the current in both wires should be the same. If the wires don't have the same amount of current, then current is leaking (returning through a different path) somewhere, and the GFCI/RCD trips. If the ground wire has potential, then hopefully it is enough to cause a short circuit and cause the over-current device to trip. If the GFCI is faulty, then you have other issues.
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  29. A "hot" wire is any conductor that is not grounded. But, yes, the term is usually limited to AC circuits in North America. The term "neutral" shown with the battery is not appropriate; I think the video author was just trying to relate home circuit wiring to the simplicity of a battery and a lamp.
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  30. Yes. Just make sure that the circuit and outlet amperage is equal to or greater than what the welder is rated to draw.
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  31. So do you understand what AC is now, or not? If you do, then you should know why the concept of polarity with AC is meaningless.
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  32. A "hot wire" is any conductor which is not grounded. Most automobiles have (–) grounded systems, but (+) ground systems also exist. It doesn't really matter which is employed, as long as it's consistent. In direct current (DC) systems, polarity matters. Electrons are negatively charged, so they are drawn to positive charge because opposite charges attract. Electrons "flow" (–) to (+). Electrocution is death by electric shock. A car battery is not likely to electrocute anyone, at least not without significant effort. You cannot get shocked if you don't complete a circuit. A circuit is a complete path from the power source back to the source.
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  33. Knob & Tube wiring having a ground is news to me!
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  34. You can be electrocuted with a tiny voltage and current applied directly to the heart. Electrocution is death by electric shock, but more specifically, it is an electric shock which disrupts your heart's ability to conduct the signals that cause it to beat. Those signals are weak to begin with, so it doesn't take much to overwhelm them... but your body is a big wet complex blob of flesh, and current flow through the body is a complex thing. It comes down to luck and physics, but the higher the voltage, the easier it is for current to overcome the resistance of your body.
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  35. Don't take it too literally. It was, in my opinion, a poorly-conceived example meant to parallel the simplicity of a DC circuit with a common battery and light with that of a AC house circuit with a light.
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  36. Because it's connected to the neutral terminal on the transformer, which, ideally carries no current.
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  37. The neutral wire is grounded, so there is very little voltage potential between neutral and ground (or neutral and a grounded casing).
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  38. Cutting the white wire is worse.
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  39. Grounding: The act of connecting to a ground system (whether earth ground or frame ground); the conductor dedicated to this connection. Grounded: Sharing the same electrical potential (voltage) as the ground (earth or frame); a conductor which has been connected to ground. Earth: The act of connecting something to the soil so as to share the same electrical potential as the Earth; the conductor dedicated to this connection; most fixed grounding systems are earthed. Bonding: The act of electrically connecting two things to ensure they are at the same electrical potential. Neutral: A conductor which, in ideal conditions, carries no current at the source; the conductor which represents a balance between two or more other electrical potentials; is usually Grounded—the groundED conductor.
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  40. A short-circuit is a circuit path of little resistance from the source and back to the source. Because there is no resistance to the flow of current, as much current can flow as the source can produce. This can quickly increase the circuit's wires beyond their current capacity, causing them to melt or catch fire, and can also permanently damage the source. Because a short circuit's low resistance causes a lot of current to try to flow very quickly, it's the easiest condition for an overcurrent device such as a circuit breaker (or MCB) or fuse to detect.
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  41. Electrons are negatively charged, so how could (+) indicate a concentration of them?
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  42. It kind-of depends on context. First, let's clarify: a "Hot" wire is any conductor which is not grounded. The neutral is connected to the grounding system, so it is not "hot." A neutral wire in a branch circuit is carries the same current as the hot does. But, at the transformer, the neutral carries no current in ideal circumstances.
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  43. They're not the same. The neutral is still grounded. From a physics standpoint, the further away the neutral gets from its connection in the service disconnect to the grounding system, the "less grounded" it is... but it's still grounded. Other than that the neutral is grounded, the two conductors are the same. They are not always interchangeable, though, because of safety considerations. Consider a table lamp. It will have a plug with "hot" and "neutral" and no ground. Because the neutral is grounded, there is not very much voltage potential there if you touch it. If the shell of the lamp socket becomes "hot" then it becomes a safety hazard when screwing in or out a bulb with the power onm because it's easy to touch while energized. The polarized plug on the lamp ensures that the shell of the lamp holder is always the neutral, and the hot is down inside the socket.
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  44. Never connect the neutral to a ground wire in a regular junction box.
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  45. I'd think It would have to be a circuit path where none of it is grounded at all. But it's safer to have grounding connections and everything not normally energized by a known voltage potential.
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  46. Got a specific question? Where in the video do you stop following?
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  47. Everyone knows batteries are not infinite power sources. It doesn't have to be depicted, and this video isn't about batteries anyways.
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  48. They are not separate phases. The voltage potential of each Hot with respect to the neutral is opposite, but they are both still in sync.
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  49. I wouldn't read too much into that diagram. It also shows "in" and "out" going to the same bushings.
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  50. Because the grounding system is connected to everything, like a big, branching tree, it can act as an antenna, and pickup electromagnetic radiation, controverting it into small voltages. Equipment can be susceptible to such flux on their ground line and cause undesired or improper operation.   Isolated ground simply means there is a dedicated ground conductor all the way to the source, such as the service panel. That grounding conductor is not connected to the "tree" and all of the rest of the grounding infrastructure along all of its points. It's only connected at that service panel (for example), and so is much less likely to act as a giant antenna.
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  51. There is no positive or negative lead in AC, so your initial question makes no sense to me. Voltage is the measure of the force of electric potential. 0V means there is no difference in electric potential. You need to be more specific about where you're sticking your probes.
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  52. You have the option of watching the video more than once, too.
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  53. Most direct current (DC) systems are (–) ground, but not all. There are (+) ground systems, too, and not just in "certain British cars." It doesn't really matter, just as long as it's consistent in a given system. "Positive to the hot wire" and "negative to the ground wire" doesn't make much sense. A "hot" wire is any conductor which is not grounded... so in a (–)-ground system, any wire which can carry (+) polarity is "hot." It doesn't "run to the hot"... it IS the hot. Same (but opposite) for a grounded wire. A ground wire is connected to ground.
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  54. It doesn't really matter. But the coloring shown is supposed to be similar to residential utility wiring... even though that makes less sense than the video author probably intended.
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  55. A "hot" wire is any conductor which is not grounded. Most direct current systems (e.g. batteries) have negative-ground systems. But that does not have to be the case, and it doesn't really matter as long as it's known and consistent throughout a system.
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  56. Batteries do not even belong in this video/discussion, they shouldn't have even been shown. The importance of polarity in a DC circuit is a foreign and unneeded concept in a discussion about AC power, despite the apparent simplicity of circuits with batteries.
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  57. @John McDonnell To expand on Steven's answer a bit... Yes, DC circuits usually have Black as negative (assuming that's the chassis or ground), and the other color (usually Red) as positive. The battery circuits in this video are not designed to be illustrative of DC circuit practices, but merely to compare the straightforwardness of a simple DC circuit to how simple a home AC circuit is. DC circuits do not typically have a "neutral" and it's just best to not take that section of the video too literally. AC wiring in homes and businesses generally has different conductors (wires) with three different roles: — grounded conductors   — grounding conductors   — hot (or live) conductors.       Electricity must flow in a closed loop called a circuit. One wire goes from the power source to the lamp, and the other wire goes from the lamp back to the power source. Both conductors carry the current. If you also connect one of those conductors to the Earth, then you erase any voltage difference between that conductor and the Earth. This is called grounding the conductor, and that conductor becomes a groundED conductor. The wire connecting that conductor to the Earth is called the groundING conductor. In fact, any other parts such as a chassis or whatnot can also be connected to the Earth through a grounding conductor. This just leaves the "hot" conductors, which really is just any conductor that is not grounded. In the United States, you can generally assume: — grounded conductors (White or Light Gray)     — grounding conductors (bare, or Green, or Green/yellow) — hot (or live) conductors (Any other color).     In the United States, Black is usually used as the primary "hot" line, Red as the secondary, and Blue as the tertiary. When three voltage phases are involved (meaning the alternating polarity changes at different times) there can be alternate color schemes in place.
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  58. Thanks. I just wish I didn't have so much damn trouble with YouTube comment formatting! I didn't even notice my comment was butchered up...
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  59. The answer is yes.
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  60. Depends on the DC circuit. In most, yes. But not all.
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  61. Electrocution is death by electric shock. I somehow doubt you've electrocuted yourself since you're writing about it. Electrocution primarily happens when the current passing through your body suppresses your heart's ability or desire to beat. Higher voltages make it easier to get the voltage into your skin, but it really depends on where inside your body the voltage is actually traveling. Picture lighting inside your body—it could go about anywhere, seemingly at random.
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  62. Ignore the battery parts in this video. Theyr'e obviously more confusing than helpful when trying to compare the simplicity of a simple battery circuit to a circuit in a home.
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  63.  @robertbrandywine  Well, I had a nice reply written, and accidentally erased it. I am not going to write it out again. But, suffice it to say, the water analogy of electricity can only go so far. They are similar in some ways, but rather different in others. Electric shock happens when you come into contact with something of different electrical potential. If the Earth is made the same potential as part of an electric circuit, then everything in contact with the Earth becomes the same electrical potential as that side of the circuit—no electric shock can happen.
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  64.  @robertbrandywine  There is little to no difference in potential between the neutral and the Earth at the point(s) where the neutral is grounded... which is the main disconnect of the structure, and the transformer. Farther away from those points there can be a little more voltage difference. But the difference is pretty negligible. The difference is also negligible for the neutral at the load and on the CT of the transformer. The only practical difference is the resistance of the conductor between those two points and associated voltage drop. It should be safe to contact the neutral, but if your body creates a better path to ground than the neutral already has, you'll still get a shock. There is 120V potential across the load, yes, but not because of the grounding system. The circuit is supplying 120V from the transformer, so that's the voltage potential. There is 120V potential between the hot and the netural, and also between the hot and the ground wire, but the neutral is designed to complete the circuit. The ground wire is only a safety backup and normally carries no current. The grounding system ensures that, should normally-non-energized parts get connected to the hot—bypassing the load—an immediate short circuit is created which will induce the over-current device to trip.
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  65.  @robertbrandywine  Yes. *There's one technical caveat. The voltage measured at the load will be lower than at the transformer because of voltage drop and the resistance of the conductors.
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  66. It's the "innovate or die" marketing principle.
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  67. Why? Because it's safer for one part of the circuit to be at the same electrical potential as the Earth. You can't get a shock if you are the same electrical potential as the Earth and you touch a conductor at the same potential as the Earth.
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  68. That's what's being talked about at 7:14. The grounding system is connected to all the metal parts that could become energized but normally are not, so that if they do become energized, a short circuit results and the overcurrent device quickly interrupts the current flow.
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  69. Remember that electrocution is death by electric shock. An electric shock does not automatically equate with death. If none of the electric utilty circuit is connected to the earth, then yes, you would not get shocked. But, a long time ago, it was decided it is much safer to ensure and expect such a connection, and to even connect half of the circuit to that connection.
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  70. @ekfliu How so?
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  71. The point of "low-resistance ground conductor" is two-pronged: 1) If a chassis or other metal casing becomes energized (which normally should not be), the low-resistance ground will quickly allow a large amount of current to flow through the circuit (a short-circuit) which should be quickly halted by the over-current device (circuit breaker or MCB). 2) The low-resistance ground offers a superior path to complete the circuit than from a person who touches that energizes chassis or metal casing. The current will mostly flow through the ground conductor, and not you.   If there is no low-resistance ground conductor, then it may take a long time for enough current to flow before the overcurrent device intervenes, and/or more current can flow through you which may hurt you.
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  72. Negative or positive ground has nothing to do with what direction the current actually follows. Electricity is not like a hammer, which you give more force in one direction than the other. The choice of which conductor to connect to the chassis is arbitrary.
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  73. And any wire that is not grouned is "hot".
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  74. https://youtu.be/W0_1xRqT8uU
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  75. @Ashy Maiden What are you struggling with?
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  76. Basically, the two halves of the phase form a combination parallel-series circuit. When both halves are loaded identically, no current flows through the neutral back to the transformer. This is almost never the case, so some current is flowing back and forth in the neutral.
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  77. Both outlets on the same duplex receptacle are almost always the same. This means any hot, neutral, or ground connection (no matter how many outlets) are interchangeable.     The ground wire should work for any circuit on the premises, so the answer to your question is yes.
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  78. Electricity always flows in a closed loop called a circuit. The lower resistance there is to that flow, the more current flows. At 8:14, he shows current flowing in the circuit, but there isn't any current flowing through the outlet because nothing is plugged into it. The potential is there (120 volts) but no current flows because there's no complete loop there. The person then touches the "hot" terminal of the outlet. This can create a complete circuit from the hot wire, through the person, to the ground system, and back to the source. The amount of current that flows depends on all of the resistance offered throughout that circuit, including the resistance of other loads on the circuit (other outlets with things plugged in, lights, etc.), the resistance of the person's body, the ground or other surfaces he's touching, etc. It's mentioned that the person is barefoot and that the ground he's standing on is wet. Pure (distilled) water does not conduct electricity, but water is also really good at dissolving minerals and metals that will allow it to conduct electricity. Only as much current will flow as the worst conducting piece of the circuit will allow. Electrocution is death by electric shock. In order for a shock to be fatal, it has to disrupt your heart's ability or desire to beat. That really depends on the voltage (how easy it is for the electric current to overcome the body's inherent resistance; dry skin, for example, conducts poorly) and where through the body the current travels.
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  79. There are not many random occurrences, but it is typically human error. For example, if the wire gets pinched on the edge of the metal electrical box, or if there's a loose connection and physical manipulation causes the wire to become detached (think like a chandelier or something).
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