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?
We need more info on just HOW it's wired before anyone can give you a
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.
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:
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.
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.
It could be miswired or you could have a ground fault situation with the
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.
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
(2) cannot reset while the hall light switch is on and the hall lights are
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.
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
(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.
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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