GFCI and circuit problem


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?
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JohnR66 wrote:

Hi, G stands for Gground. Checked ground wire? Ground is bare copper in the outlet boxes or green wire on GFCI.
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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 mixed up?
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?
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Check for dead outlets in the basement and garage.
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On Aug 10, 12:10 pm, snipped-for-privacy@milmac.com (Doug Miller) wrote:

Good idea; for example our now enclosed garage was once an outside car port. And we have one now unused outlet out there that is 'on' one kitchen circuit!
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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.
Jimmie
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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.
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JohnR66 wrote:

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.
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Check for a neutral to ground short
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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 the GFCI.
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 the problem.
HTH and good luck.
Paul F.
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JohnR66 wrote:

May I offer the "Trouble With A GFI" section at: http://tonyelectric.com/gfi
I would appreciate feedback on it.
Anthony Straight http://tonyelectric.com
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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 outlets

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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.
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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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snipped-for-privacy@aol.com wrote:

In addition they have a second current transformer that tries to inject a current on the neutral (or both neutral and hot). GFCIs will trip on a downstream N-G connection with no load.
--
bud--

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