GFCI Trips immediately after energizing circuit

Question

I am not an electrician, however, used to work for an electrical engineering firm so I’m pretty familiar with electrical circuits. Having said that I purchased a home where the previous owner had done some sketchy remodel work.

One of the areas he remodeled has a GFCI outlet in it. It is in an office downstairs with what we call a sitting room adjacent. All of the receptacles in the office and two in the Sitting Room are on the same circuit. That GFCI tripped the other day, I thought it had gone bad, as it would not reset so I replaced it. The new one tripped immediately after energizing it (yes it was installed correctly).

I unplugged everything downline, but still tripped, I checked every outlet downline for loose wires, etc. all was good. The GFI of course is at the head of the circuit. Panel —> GFI —> Load (7 outlets). I double-checked the ground, neutral and hot wires, only the hot wire coming from the panel has power coming to it.

When I connect the hot and neutral coming from the panel the GFI operates correctly and the test plug indicates correct wiring. As soon as I plug in either The neutral or hot load (yes I am plugging it into the load side of the outlet), the breaker trips and won’t reset. If I bypass the GFI everything works fine - all circuits test as correctly wired, nothing shorts out, breaker stays cool, and everything works.

I’ve tried two different GFI outlets in case I had a dud. Am I good just to put a standard receptacle in place of the GFI? In case you were curious I believe the reason there is a GFI there in the first place is the office was originally part of the oversized 5 car garage.

Answer 1

There are various faults that can trip a GFCI, in addition to the obvious leakage from hot to ground.

Neutral-to-ground shorts can lead to current that should have returned via the neutral going via ground instead, tripping the breaker.

Shorts to other unrelated circuits (e.g. the neutral of your circuit shorting to the neutral of another) can also cause unexpected diverted currents, even when no load is being drawn on the circuit you're fault-finding. Wiring using "borrowed neutrals" has a similar effect, where somebody has used the same neutral for two circuits.

Removing the protective device because it keeps tripping generally isn't a good idea. It's trying to tell you that something is wrong.

Answer 2

It does not seem wise to replace a GFCI with a standard outlet when it appears to be doing its job and finding a ground fault on the load wiring.

Try disconnecting all but the next load outlet. If it's OK, add only the next outlet. Repeat until the problem repeats. Know where to look for the problem. Don't assume it's not a problem.

As soon as I plug-in either The neutral or hot load (yes I am plugging it into the load side of the outlet) The breaker trips and won’t reset.

Please clarify. The GFCI trips, or the breaker trips? Presumably the GFCI, since you say it works fine with the GFCI bypassed.

Second, you need to connect (not plug, that's what you do on the front side of the device, not with the load wiring) both the Hot and Neutral (with the circuit shut off) and then re-energize. Don't get all EE chip on shoulder and try to connect them live, especially to a GFCI. Feel free to get all EE I own a meter and know how to use it though. That could provide some useful insight.

Answer 3

If there is nothing plugged into the downstream outlets and the GFCI still trips on the load side, you have an issue. I've said this before here and will say it again... one possibility is rodent damage. Hard to find. All you can do is pull out all the downstream outlets and disconnect them one at a time until the GFCI resets successfully. If you can identify it, start at the outlet at the end of the run, then move up, outlet by outlet, until, hopefully, when you disconnect a certain outlet, the GFI will reset. Then, you'll know between which outlets the fault/damage is.

There may be other causes, I DK. but rodent damage is a total PITA but relatively common.

Answer 4

I had the same problem where a GFCI tripped immediately. The answer about the borrowed neutral caused me to re-examine my wiring. When I did that, I realized I had the line and load neutrals connected. I separated them and now all is well.