Some one please explain the dangers in this practice

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Sparky220

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

petersonra said:
how is this any more dangerous than if the neutral wire came loose and touched the metal case of the refrigerator?
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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. :roll:
 
Explain dangers.

Explain dangers.

This is called objectionable current. It creates a parallel path for current to return to the source. Mike Holt has a video on this.
 
Three pronged dryer receptacle which was allowed until NEC 1996 bonded the chassis to neutral and did not have a EGC to panel.
Broken neutral is more common before the meter where it is exposed to the elements. When the neutral is lost, your washer has path to ground and the center tap neutral (depending on where the break is) through the EGC and possibly the water supply if it is connected with stainless braid wrapped hose and attaches to grounded water line. So you end up building 120v between dryer and washer cabinets. It was phased out because of this danger. The risk is much higher with a metal frame tool because the cord is handled much more frequently. Loose neutral in a power strip means the chassis becomes hot only when the tool is activated.

If it is moved to an older house and the chassis is not connected to neutral, you'll have a floating frame. If moved to a newer house and the frame is bonded, you inadvertently create a neutral to ground bonding at the dryer.
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If another grounded object should contact whatever is connected to this bootlegged EGC, you have parallel path(s) for neutral current to flow over objects not intended to carry current.

"stray voltage" problems are almost always a result of unintended current paths of the grounded conductor.

This sort of bootleg may go without any noticeable problem for years in some cases. If in a wood framed building with no other grounded objects in the vicinity you can have full 120 volts on the frame of an appliance and never have a nearby ground reference to cause you to notice it. Of course if you have full 120 and bootlegged EGC, you probably have completely open neutral and the appliance doesn't operate, but my point here is there is no shock hazard in that situation because there is no grounded object within reach.
 
kwired said:
If another grounded object should contact whatever is connected to this bootlegged EGC, you have parallel path(s) for neutral current to flow over objects not intended to carry current.

"stray voltage" problems are almost always a result of unintended current paths of the grounded conductor.

This sort of bootleg may go without any noticeable problem for years in some cases. If in a wood framed building with no other grounded objects in the vicinity you can have full 120 volts on the frame of an appliance and never have a nearby ground reference to cause you to notice it. Of course if you have full 120 and bootlegged EGC, you probably have completely open neutral and the appliance doesn't operate, but my point here is there is no shock hazard in that situation because there is no grounded object within reach.
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Just want to say that "grounded object" does NOT have to be electrically grounded per classic or NEC definition. The aforementioned air compressor that bit me... July, sweating like crazy (why do all of these shock stories begin with that?) I grab the handle of the compressor to pull it, wheels are locked up. For more leverage, I place my other hand on a nearby jet-ski trailer...several hundred pounds of metal... those rubber wheels did not help me, I got smashed (shocked) hand-to-hand. The tongue of the trailer was on a wooden block. Had my body's resistance not been so low, I might not have even noticed it. As it was, it was very painful and about the most dangerous way to get shocked.

The compressor had a fault in it. I pulled the 3 prong receptacle, only to find 2 wires connected. So the compressor frame sat at 120V to ground until it tried to find another path to the source, through me. That event was 20+ years ago, it was what got me interested in electrical; I didnt want that to happen again. The same day I learned about GFCI receptacles and installed one, and got a new compressor.
 
Had an inspector tell me once, he would rather see the jumper from neutral to EG terminal at a device vs nothing.:jawdrop: I didn't ask him why the heck do I spend so much time in Code classes if that is your thoughts. Carpenters that had done the remodel replaced old 2 wire with new devices and jumpered all of them.
 
JFletcher said:
Just want to say that "grounded object" does NOT have to be electrically grounded per classic or NEC definition. The aforementioned air compressor that bit me... July, sweating like crazy (why do all of these shock stories begin with that?) I grab the handle of the compressor to pull it, wheels are locked up. For more leverage, I place my other hand on a nearby jet-ski trailer...several hundred pounds of metal... those rubber wheels did not help me, I got smashed (shocked) hand-to-hand. The tongue of the trailer was on a wooden block. Had my body's resistance not been so low, I might not have even noticed it. As it was, it was very painful and about the most dangerous way to get shocked.
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Please do not take this the wrong way I am sure you got the shock you said you did but I feel there had to be a path to ground beyond rubber tires and wood blocks.

Was it all wet?
 
iwire said:
Please do not take this the wrong way I am sure you got the shock you said you did but I feel there had to be a path to ground beyond rubber tires and wood blocks.

Was it all wet?
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I agree. Modern (and for past 50 or more years) tires would likely have been conductive enough to help eliminate static charge buildup, but are not low enough resistance to pass any significant current at 120 volts.
 
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