Comments by "Ted Sanders" (@surferdude642) on "The Engineering Mindset" channel.

  1. This could be normal in GFCI receptacle or regular receptacle as well. Plugging in a tool or appliance with the power off (tool or appliance) will prevent this problem. If the receptacle is old and/or not gripping the cord very well, you should change it. Check the plug condition also.
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  2. I like the way you show the rotating magnets in relationship to the sine wave. If you stop the video at peak voltage and 0 volts and notice the position of the magnet it helps in understanding this important point. The plus or minus in AC is directional flow?
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  3. ​ @Gt92279 Some of it would, but maybe not enough to trip the breaker. In the meantime you'd have parallel paths of current and that's a shock hazard. This condition in electrical wiring is known as "objectionable current".
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  4. All of it is used, not really consumed when the lights are on.
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  5. No, because you're measuring the voltage (potential difference) between opposite poles. One is +120v and the other is -120v and 0v is the mid point (neutral). If you measured a point on one one of the bus bars and another point on the same bus bar, then you'd get 0v because there's no potential difference. As an analogy, say if you're at home and you had to drive somewhere. Your home is 5 miles from the interstate highway and your destination is 5 miles on the other side of the highway, total is 10 miles.
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  6. The ground it shares is the equipment ground aka the EGC, equipment grounding conductor. The grounding electrode is part of the GEC, grounding electrode conductor. You need a grounding electrode, ground rod in each building to protect them from lightning strikes.
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  7. ​ @fnscomedycrew If you have 40 amps on each side or line, you would have 80 total current consumption, but zero on the neutral upstream of the main panel neutral bus bar because it's a balanced load. Even if it's divided unevenly the current load would be the same, but some current would return on the neutral.
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  8. That's a good observation you made and it doesn't sound right. You should call an electrician to have a look at it.
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  9. You're correct, you'll need a 3 wire cable between the light and the first switch, then pigtail it to the neutral from the power cable and leave the other end capped in the first switch box. In 3-way and 4- circuits only one switch needs a neutral wire.
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  10.  @tookitogo  Good information, you're right about TV's, computers, etc., and they are normally plugged into surge protectors/power strips and left plugged in all the time, so sparking would not be an issue.
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  11. No, you will have 240v only.
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  12. My house has a concrete slab and I cannot find evidence of a grounding rod, I think it has an "ufer" ground.
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  13. @tim g Thank you
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  14. Yes, it will work but the switches will be in opposite positions when the light is on and in the same position when the light is off. It's a little odd maybe, but who would care or notice especially if the switches are far apart.
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  15. The current always tries to return to its source, which in this case is the transformer. In a natural condition such a lightning strike, the source is the earth, and the ground rod provides that path if the lightning strikes the building.
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  16. Because the breaker would trip immediately.
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  17. Then a ground fault in the circuits attached to the sub panel cannot be cleared and metal parts will remain energized.
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  18. Your first question is impractical, but yes it would be bad. The answer to your second question is NO, the ground wires that attach to receptacles and switches are part of the internal circuitry and are known as equipment grounding conductors (EGC). Parallel paths refers to current traveling on both wires within this circuit. The grounding electrode is part of the external system and is known as the grounding electrode conductor (GEC). The EGC protects the system from internal or man made faults. The (GEC) protects the building from natural causes, mainly lightning as it attempts to direct the current to the ground which is the source of the lightning.
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  19. You need to have a ground and neutral bond in the main panel or first disconnect means so the current returns via the neutral wire to the transformer and trips the breaker. Otherwise all the metal parts will remain energized.
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  20. Why do you think that?
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  21. Neutral and ground must be connected together only at the main panel and no where else, including sub panels. The reason is to guarantee a 0 voltage reference point. This is necessary for the circuit to operate safely and for circuit breakers to trip when needed.
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  22.  @igorivanov7232  I'm not sure where you live, I'm in the US where we have a 120v system by center tapping the secondary windings of a 240v coil and hence the return or neutral wire. 240v is commonly used for high power appliances by connecting to opposite poles and omitting the center tap. In this case there's no neutral wire and the return shifts with the frequency from one pole to the other. Both are hot wires. You may have a loose hot wire that is making contact with metal somewhere in your system. You should call a local electrician to fix it. Changing the receptacles may do it, but a grounding rod will not help. You'll need an equipment grounding conductor to provide a fault path from the equipment to complete the circuit and trip the breaker. A grounding rod is mainly used to direct external current, lightning strikes, to earth.
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  23. ​ @MauriceCalis That's it.
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  24. I think it may be because the impedance is constant. Not sure, though.
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  25.  @govindharaju3079  ok then, I did say that I wasn't sure. You seem to know something about it, if you do some research you should be able to find the answer, since nobody replied with one yet.
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  26. Keith Newton Do they have concrete slabs? If so, they may be using a modern version of an "ufer" ground, where the ground wire is connected with the rebar.
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  27. The light switch opens and the circuit on the hot wire only.
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  28. True, but the neutral center tap of the transformer, the source, is connected to earth ground.
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  29. I don't think that it is. The point of the ground wire is to provide a low impedance path in case the hot wire contacts a grounded metal case. The neutral wire is not involved in this scenario. If the ground wire contacts say the neutral screw on a receptacle the return current will be shared between the neutral and ground and have parallel paths of return current which is also bad because of a potential shock hazard. If you have a GFCI receptacle in the circuit, it probably wouldn't reset or it would trip when you plugged something in and turned on the switch. The insulation or not has nothing to do with it.
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  30. ​ @christoph1039 No, it's really 240v, which ever bus you place the multimeter leads is irrelevant.
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  31. The term "line" is the power from the source. The term "load" can have a couple of different meanings, depending on the context. In a GFCI receptacle for example, the "load" feeds the downstream outlets. Otherwise, the "load" is anything that is plugged into a receptacle demanding current or power to function.
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  32. To your first question, it does sound correct, but I can't be 100% certain without seeing it. You may want to call an electrician to verify that. The answer to your second question is absolutely not. The neutral and ground connection must only be made at the first disconnect, usually that would be the main panel. Anywhere downstream, the neutral and ground must be separated and under normal operation, the ground wire must not carry any current and the neutral wire must carry all of the return current to the only ground/neutral bus in a 120 volt circuit. The one exception would be in a multi wire branch circuit, the neutral wire will carry only the unbalanced load and the rest would return on one of the hot wires. You can't carry current on both the neutral and ground because it would a parallel path and may not trip the breaker. It would be a shock hazard since all the metal components would be energized.
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  33.  @ShyRage1  You said that you added a ground bar to the sub. I don't get that, because your sub panel must already have a ground bar. Did you need a second one? The ground bar must be grounded to the panel frame, but the neutral bar must be isolated from the frame and the ground bus bar. You said previously that the main panel has a crossing bridge joining the two bus bars. Are ground and neutral wires sharing those bus bars or are they occupied by neutral wires only?
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  34.  @ShyRage1  So all the circuits in the sub panel are ungrounded then the receptacles should be 2 prong or replaced with a GFCI or multiple GFCI's for safety. If the ground and neutral share the bus bar in the main panel which is typical, it indicates that the equipment ground and neutral wires are not connected anywhere else if it's correctly wired. The white wire is connected to the ground at the meter box. The ground wire may also be connected to the ground rod. The ground wire in the meter box grounds the meter box housing. I think that different jurisdictions have different regulations on whether the grounding electrode system and ground rod is terminated from the main panel or the meter base. That's my understanding, and I hope this helps.
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  35.  @ShyRage1  Are the circuit wires behind the wall running in metal conduit?
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  36.  @ShyRage1  okay, I got it now, good job, thanks.
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  37. Electrons only move in a closed loop when a load is applied. This loop includes the secondary windings of the transformer. In the case of a short or an over current situation the breaker will trip. This has nothing to do with the grounding rod.
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  38.  @lightweaverx4381  True enough, but my comment was intended to be applicable to residential wiring in the U.S. specifically, based on my understanding, not about electromagnetism in general.
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