I'm trying to solve an issue at my brothers house. He came home and the
outlets around his kitchen had no power. I found the GFCI was tripped. I
reset, but it trips instantly. I unplugged every device and it still trips.
I bought a new GFCI, still trips.
Next I checked the load side hot to neutral with my meter. Infinity
resistance (nothing pugged in). I checked to be sure I was getting 120 volts
to the black wire and that it was connected to the line side of the GFCI.
Some other notes:
If I bypass the GFCI, The circuit works (no short)
With load side of GFCI not connected, it does not trip.
If I touch the black load side wire to the hot load side of GFCI, no trip.
If I touch the white load side wire to the to the neutral load side of the
CFCI, it trips! (I'm confused on that one)
Bathroom has its own GFCI circuit that works and I can find no outside
outlets on the dead circuit.
I'm puzzled on this one. Any ideas?
Tony: A neutral/ground short/leakage yes. That could cause slight
current to flow in the neutral; but why when 'nothing' plugged in?????
Unless something is causing the neutral wire (beyond/downstream of the
GFCI) to have a slight potential rise; which 'might' be explained as
you suggest by a ground-neutral short somewhere?
Or does it suggest that the downstream neutral is 'shared' (possibly
illegally) with another circuit? Or somebody did an improper job of
replacing an outlet or something and got the ground/neutral crossed or
Because GFCI operate when there is an unbalance in the current flowing
in the live and neutral wires; they can in fact despite their name be
used in a non grounded outlet situation.
The described problem is a puzzling one. Am wondering if there is damp
wiring/outlet beyond (downstream of the GFCI equipped outlet?
Or is there a dishwasher/garbage disposal motor/booster water heater
etc. hooked in somehere; under a counter?
My kitchen and one wall of my garage(one outlet) was on the same GFCI
breaker and I started having trouble. The problem was the result of me
leaving a long extension cord plugged in. Whenever there was something
plugged into the extension cord(usually a vacuum cleaner) no problem,
whenever it was just coiled up on its hook it would intermittently
trip the GFCI breaker. Anyway, rewired the garage so that it is on its
own breaker and turned the extension cord into speaker wire.
Go to the next outlet that is being fed by that GFI and disconnect
every wire. Now connect the original GFI outlet you were working on.
If it does not trip, you have a problem downstream. You will have to
repeat the process at evry outlet until you can isolate the problem.
A GFCI device trips when the currents in the two sides differ by a very
small amount (probably less than 0.015 amp). Look for a leakage path.
Unplug all loads at all outlets and see if it still trips. Also, very
long runs of wire can trip the GFCI just due to capacitive current.
Make sure hardwired appliances like the disposal, microwave, clock
outlet, etc. are not improperly on same circuit.
But..by measuring infinity between black and white you know there are
no loads you don't know about. By bypassing the gfci and not blowing
breaker you know there is no short from hot to ground or neutral. Is
your meter sensitive enough to detect difference between very high
resistance and infinity? Doesn't take much of a leakage path to trip
When you connect the neutral and the GFCI trips, was the hot still
connected? It sounds like it was not from your description. If the
hot was not connected, and the GFCI still trips when you connect
neutral, then current must be flowing in the neutral from some other
source. Measure the voltage from neutral to ground (on the wires
going to the outlets) with the GFCI disconnected. If there is no
voltage, then measure resistance from neutral to ground. It should be
infinity with the GFCI disconnected. It's possible the neutral is
cross tied to some other circuit.
If all that seems to check out, then I would start isolating sections
of the wiring by disconnecting outlets along the way. Start in the
middle if you can figure out how the wires were run. that will
isolate the problem to a half, then repeat in that half until you find
HTH and good luck.
If the house was wired by NEC standards, no other outlets but the kitchen
counter outlets should be on the load side of the GF circuit, no bathrooms,
no garages, basements, etc. From your description, I would guess that a bare
ground wire has come in contact with a neutral terminal in one of the
protected outlets. Open each up, and pull the receptacles out of the box,
leaving them connected, then try the gfci device. Also, keep in mind that
you should have at least two separate 20 amp circuits for kitchen counter
I did have the copper ground lead connected, so it sounds like a neutral to
ground fault. That puzzeld me because I did not know GFCIs detected ground
to neutral faults, so that must be where the problem is. I will inject a
signal in the neutral ground loop and use a telephone pickup coil and
amplifier to to see I can locate the fault.
Thanks for all the help.
GFCIs look at the amount of current going out on the hot and compare
it to what comes back on the neutral via a dual would current
transformer. If you have a neutral/ground fault, some of that current
comes back on the ground and the transformer signals an imbalance..
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