Another grounding question

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mikeym76

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An outside GFCI, wired with 12/2 UF cable, is located twenty feet from the house. It is an older home wired with out a grounding conductor. The receptacle is housed in a wheather proof bell box, mounted on a pressure treated 2X4, six inches above ground. All wires are terminated on there correct terminal screw: hot to gold, nuetral to silver and ground to green. However, placing a knee on the physical ground and one hand on the box you will feel a slight tingle.

Question #1: What is causing a potential difference?

Question #2: Will a ground rod bonded to this bell box eliminate this hazard?
 
mikeym76 said:
An outside GFCI, wired with 12/2 UF cable, is located twenty feet from the house. It is an older home wired with out a grounding conductor. The receptacle is housed in a wheather proof bell box, mounted on a pressure treated 2X4, six inches above ground. All wires are terminated on there correct terminal screw: hot to gold, nuetral to silver and ground to green. However, placing a knee on the physical ground and one hand on the box you will feel a slight tingle.

Question #1: What is causing a potential difference?

Question #2: Will a ground rod bonded to this bell box eliminate this hazard?
Click to expand...

You said that it was wired w/o a grounding conductor, yet you say that the ground is tied to the green.... don't know if that is part of your problem

anyway, check w/ a voltmeter and see what you have
 
mikeym76 said:
An outside GFCI...

Question #1: What is causing a potential difference?

Question #2: Will a ground rod bonded to this bell box eliminate this hazard?
Click to expand...

Q1: Sounds like you may have current on the equipment ground. Make sure the neutral is not bonded past the service disconnect. Equipment grounding needs to remain separate from the grounded conductor (neutral) past the service disconnect to eliminate parallel neutral paths.
Then check the source neutral and qualify it as good it may be failing, this along with incorrect bonding is common in older houses.

Q2: No, an electrode is not the remedy.
 
Because there is no ground you cannot bond the box. It's ungrounded. I take it there is no metal raceway either. That's why GFCI receptacles are used in places where there is knob and tube wiring. You can try bonding the box to the neutral wire. Use a jumper. This should prevent shock by tripping the breaker or blowing the fuse.
 
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Mikey, welcome to the forum! :smile: (Do you like Quaker Oats cereal? :D)

Do you feel the tingle even with nothing plugged into the receptacle?

Is there or is there not a GEC in the UF? If so, where does it land inside?
 
the way I understand it, you have 12-3 UF feed from an ungrounded system. Can you find where it is tied in? I am guessing that the ground wire and neutral are both tied together with the neutal from the original circuit, if that is the case, you are getting current to the metal box through the "bootlegged" groundwire. lifting the ground wire should remedy the issue. If the ground isnt bootlegged, you should megger the UF, you may have bad insulation and a short from neutral to ground.
 
ultramegabob said:
Bad advice, I actually believe this is what is causing the problem....
Click to expand...

Agreed.. Even though, eventually, they technically are bonded together - DONT ever tie the ground and neutral together at a receptacle. Like UMB said, this very thing probably IS the reason its happening.


~matt
 
how to troubleshoot this....

first check to see if the Uf is landed in the panel. if it isnt, then check for continuity between ground and neutral at the recept, if you have continuity there is your problem....

if you dont have continuity, from neutral to ground, check for voltage from neutral to ground, if you have voltage, you have a short from power to the ground in the cable.
 
If there is no metal raceway and no equipment ground wire then you would have to use the neutral otherwise there is no effective fault current path. If the hot wire touches the box then you run the risk of someone being electrocuted. It could be that the metal yoke of the receptacle is electrically connected to the box and because it's a GFCI it has no grounding terminal. That may be the reason for the current flow to the box. Rubber washers might solve the problem.
 
erickench said:
If there is no metal raceway and no equipment ground wire then you would have to use the neutral
Click to expand...

That is a direct NEC violation and creates it's own set of problems if this neutral opens. In that case you can energize the metal parts of any equipment plugged into the circuit.
 
iwire said:
That is a direct NEC violation and creates it's own set of problems if this neutral opens. In that case you can energize the metal parts of any equipment plugged into the circuit.
Click to expand...


I may be wrong but I had the impression that eric was talking about this as a testing method not a permanent install. At least I hoped he was. :smile:
 
erickench said:
If there is no metal raceway and no equipment ground wire then you would have to use the neutral otherwise there is no effective fault current path. If the hot wire touches the box then you run the risk of someone being electrocuted. It could be that the metal yoke of the receptacle is electrically connected to the box and because it's a GFCI it has no grounding terminal. That may be the reason for the current flow to the box. Rubber washers might solve the problem.
Click to expand...

This circuit in question does include a equipment ground! And it is supplied by a grounded system.

Your advocating violations of 250.4(A)(4), 250.24(A)(5), 250.110, & 250.142 at a minimum. This action will create a parallel path for neutral current!

Just fix the equipment grounding DON?T bond the neutral!
 
erickench said:
...It could be that the metal yoke of the receptacle is electrically connected to the box and because it's a GFCI it has no grounding terminal. That may be the reason for the current flow to the box. Rubber washers might solve the problem.
Click to expand...

You should know the industry does not supply listed rubber washers for this action!

If current exists while nothing is plugged into this outlet there is a problem needing repair ahead of this outlet, it does not need a band-aid it needs repair! :mad:
 
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