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Thread: Some one please explain the dangers in this practice

  1. #1
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    Some one please explain the dangers in this practice

    What are the hazards of pigtailing a neutral to jump onto ground screw in a receptacle? In purposes to fool the receptacle testers. If they are on the same bus bar how is this bad? I know you are not supposed to do this, but why? Any one care to chime in and possibly make an illustration

  2. #2
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    OK, I wish I was good with graphics so I could draw this out but I will try to explain it.

    If you do what you suggest, and the neutral going back to the panel becomes open (broken, loose connection etc.) anything that is connected to that neutral becomes live. So if it was say the refrigerator circuit the metal case of the refrigerator would become live relative to correctly grounded objects.

    This is one of those cases where you think, 'It goes to the same place anyway, what difference can it make?' It can make a huge difference, it can kill people

  3. #3
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    Quote Originally Posted by iwire View Post
    OK, I wish I was good with graphics so I could draw this out but I will try to explain it.

    If you do what you suggest, and the neutral going back to the panel becomes open (broken, loose connection etc.) anything that is connected to that neutral becomes live. So if it was say the refrigerator circuit the metal case of the refrigerator would become live relative to correctly grounded objects.

    This is one of those cases where you think, 'It goes to the same place anyway, what difference can it make?' It can make a huge difference, it can kill people

    Makes sense and pretty much what i was thinking, I wish someone could draw a graphic

  4. #4
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    Lets imagine just a single outlet on a dedicated circuit for a refrigerator but it is old two wire cable with no ground wire. Someone at some point installed a three wire outlet and jumped the neutral to the ground terminal on the receptacle as well.

    At this point its almost OK, but the case of the refrigerator will be raised above ground potential by the amount of voltage drop on the neutral This should be only a couple of volts at most. Likely no one would be hurt and if a live wire inside the fridge touched the refrigerator case it should trip the breaker or blow the fuse.

    However now imagine that the neutral comes off at the panel.

    The current path could be from the hot wire at the receptacle up the cord to the refrigerator, through the compressor windings and back out the cord on the neutral but now it can't get to the panel from there so the refrigerator does not run. BUT .. the current can go across the neutral to ground jumper at the plug back up the cord and energize the case of the fridge. It would sit that way unnoticed till someone touched it and something grounded like the sink.

  5. #5
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    In addition to iwire's description, if you do as indicated, there will be current that should only be traveling back through the neutral, will also provide "normal" current to travel back on the EGC which should not carry current normally.
    Ron

  6. #6
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    how is this any more dangerous than if the neutral wire came loose and touched the metal case of the refrigerator?
    Bob

  7. #7
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    Ron, the OP is asking about where there is no EGC at the receptacle, thus the 'need' to jump neutral to ground with a cheater wire.

    Quote Originally Posted by petersonra View Post
    how is this any more dangerous than if the neutral wire came loose and touched the metal case of the refrigerator?
    If the neutral touches a grounded refrigerator case, hopefullly there will be enough current flowing on the grounding (and thus ungrounded too) conductor to cause the breaker to trip. If the frig isnt grounded, the frame will sit at ~120V and shock you next time you provide a sufficient path/connection to an item at a lower potential.

    I've been nailed by an air compressor and a bench grinder that were plugged into 3 prong receptacles with no ground or a jumper from ground to neutral. If there is no EGC at the receptacle, a GFCI is the way to go, tho dingy HI's will still fail it because their plug tester shows an open ground.
    Electricians do it until it Hertz!

  8. #8
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    Quote Originally Posted by JFletcher View Post
    If the neutral touches a grounded refrigerator case, hopefullly there will be enough current flowing on the grounding (and thus ungrounded too) conductor to cause the breaker to trip.
    This won't happen unless there is some king of ground fault protection.
    Once in a while you get shown the light
    In the strangest of places if you look at it right. Robert Hunter

  9. #9
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    Quote Originally Posted by ActionDave View Post
    This won't happen unless there is some king of ground fault protection.

    Please elaborate on you're statement

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    Quote Originally Posted by ActionDave View Post
    This won't happen unless there is some king of ground fault protection.
    Quote Originally Posted by JFletcher View Post
    If there is no EGC at the receptacle, a GFCI is the way to go
    Agree.
    Electricians do it until it Hertz!

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