GFCI outlet troubleshooting

I installed a GFCI outlet in a hall bathroom, following the manufacturers instructions for determining which of the two sets of wires were load vs. line. The install and testing seemed to go o.k., however when I turn on the hall light the outlet immediately trips. I can turn off the light and reset the outlet, but can't reset while the hall light is on. Is it possible that the load is too much for the 15 amp GFCI outlet? Or is it more likely that I have something miswired?
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Rampy wrote:

We need more info on just HOW it's wired before anyone can give you a definite answer.
AFAIK GFCI outlets will NOT trip on pure current overloads, the circuit breaker ahead of them does that job.
So, I'd say that something IS miswired, or perhaps a ground fault leak in the light fixture is the source of your problem.
Jeff
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Jeffry Wisnia
(W1BSV + Brass Rat \'57 EE)
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Not being an electrician, I'll do my best (and appreciate the help)...
Two sets of wires enter the box, each with white, black, ground. I determined the line set by leaving only one set of the wires connected to the outlet, powering on at the breaker box, and seeing that power still flowed to the outlet. I didn't test the other pair, but assumed them to be a load. The grounds are all bound together and connected to the common copper ground on the box and to the outlet ground. Line in at the top, load out at the bottom. Sorry, but I don't really have information beyond that. Thanks again for the info.
Jeff Wisnia wrote:

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Rampy wrote:

It sounds like something is wrong with the wiring going to the downstream light causing the GFCI to sense a current imbalance. Could be a shorted or reversed ground/neutral. Or somehow the light could be connected to another neutral, not the one flowing through the GFCI. Of could be a true ground fault in the light.
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Rampy wrote:

Without any insult intended, do both the black wires go to the brass screws on the GFCI and both the white wires to the silver screws? (Or to the screws marked with letters like L and N?)
Failing that not being correct, I'll side with what trader4 just said, the problem is downstream. switch off the breaker and take that hall light off it's box and tell us what you find. You didn't say whether that hall light was controlled by a wall switch or a pull string, (Unlikely, huh?) but if it's a wall switch open that up and look for anything unusual there too.
Good luck,
Jeff
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Jeffry Wisnia
(W1BSV + Brass Rat \'57 EE)
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Is the hall switch a regular switch or a 3-way?
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It could be miswired or you could have a ground fault situation with the hall light.
If the hall light is the only load and not some other bathroom outlet, outdoor outlet, basement outlet, or garage outlet, I would remove the hall light feed (The load) from the GFCI and just splice those wires together with the hot wires. Put pigtails on them to feed the GFCI and put it all back together in the wall.
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Here's an easy test that would provide some new info:
Remove all lighbulbs controlled by the hall light switch. Now switch on the hall light switch and does the GFCI still trip?
Other than the hall lights, are there other receptacles downstream of the GFCI? If so, you can do additional testing there.
When you say "cannot reset when the hall light is on", do you mean: (1) cannot reset while the hall light switch is on and the hall lights are off (2) cannot reset while the hall light switch is on and the hall lights are also on!??
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With the lightbulb removed, the outlet does not trip when I flip the hall light switch (not that I know what that indicates).
With regard to your other question, the answer is (1) "cannot reset while the hall light switch is on and the hall lights are off".
I've pulled from the wall/ceiling each switch, light, outlet, etc. (all at the same time), to make sure that no ground wire is touching the base unit, but to no avail... flipping the light switch for the hall (with a light bulb present) trips the GFCI outlet. I've gone back through the manufactures directions for hooking up and have (afaik) the correct wires connected to the correct nodes on the outlet.
Ugh.
peter wrote:

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This means the current going into the black wire (of the hall light circuit) is not all coming back via the white wire. The current can only go to the ground wire or to the neutral wire of another circuit.
(a) the neutral side of the hall light is connected to a ground wire instead of the neutral wire (b) the neutral side of the hall light is connected to a ground wire and the neutral wire (c) the neutral side of the hall light is connected to a neutral wire of a different circuit instead of its own (d) the neutral side of the hall light is connected to a neutral wire of a different circuit plus its own
You may be able to identify the above 4 situation by visually inspecting the junction boxes involved.
(optional) To verify my suspicion, disconnect the white/black pair from the load side of the GFCI and connect only the black wire to the line side of the GFCI (there should be two holes, one for power, one for this), and cap off the white one. I bet you can still turn on the hall light this way. This just confirm it's one of the 4 possibilties above.
If you are unable to locate the problems by visual inspection. You'd have to do some more test using a multimeter. The procedure would fill half a page. Do you want to do it?
Someone else please verify my logic.
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wirenut on the white wires. If you have a smidgen of copper showing it can short to the box, hickey or something when you shove the whole mess back in. As soon as that circuit starts pulling current some goes back on the ground. This is the most common cause of ceiling fans tripping AFCIs too.
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