GFI Breaker Trips

A 15 Amp GFI breaker tripped off a few weeks ago and now it cannot be reset without immediately tripping again. Replacing it with a new GFI breaker did not help although a non-GFI breaker worked fine for at least 30 minutes.

The cable from the breaker box provides power to the master bedroom and walk-in closet, en suite bathroom, 2nd bathroom (used by wife), hall lights, guest bedroom, and finished attic. I’ve isolated the problem to one branch, enabling restoration of power to most of the master bedroom, both bathrooms, hall lights, and attic space. The master bedroom closet and a nearby outlet, plus the guest bedroom are without power.

In the light switch box for the master bedroom closet, the feed line is connected to a cable with 3 wires plus ground that goes to a ceiling light. The red wire is switched while the black and white are connected in the box above the light to another cable that apparently provides power for the guest bedroom. Is this switched red wire enough by itself to explain the GFI tripping off or is it more likely that the cause is somewhere in the guest bedroom?

(I haven’t yet determined guest bedroom wiring details but the cable from the master bedroom closet light switch does NOT go directly to any of the 3 light switches in the guest bedroom. I will check the two overhead lights and/or some outlets if the red wire in the closet is probably NOT the cause of the GFI tripping.)

Be glad that the problem happens within a short time span, Something that would happen once every couple weeks or so would probably be harder the trace. I wonder if the problem would be easier to solve with a ten or even a 5 amp breaker. It might happen more frequently which always helped me. Any sign of Pixie and Dixie? (Mice from the old cartoons)

All of that is on a single 15A breaker? That seems like a lot, spread over a big area. At my house, that might be 4 breakers.

That's exactly the approach I would take - isolate the problem to an ever-smaller area. If you're lucky, the problem will be near a receptacle, a light switch, or a light fixture. If you're unlucky, the problem will be near a hidden junction box or a hidden splice, which of course wouldn't be kosher at all. By breaking (temp disconnecting) the circuit at different places, you should be able to further narrow it down.

Do you have one of those plug-in receptacle testers, the ones that light up to show whether the receptacle is wired correctly, or with reversed polarity, or without a ground, etc. Those can be handy for troubleshooting, but you may have to use a non-GFCI breaker during troubleshooting.

Jim, I completely agree with you, especially for the two bathrooms which need to be on GFI, while I'm not so concerned about ground faults in the dry locations. It's hard to figure why they put so much on one circuit; the house only 30 years old. However, it makes no sense to rip up walls now, just to run new branch circuits. Instead, I've replaced incandescent bulbs in the house with LEDs wherever it was practical, which I figure potentially reduces power needed by 15 - 20 amps.

Additional troubleshooting today may prove that the master bedroom closet with its red switched wire is the cause for the GFI breaker tripping. If this turns out to be true, can you tell me how to rewire this to keep the load balanced?

A wire being switched or not isn't the problem. Where is this GFCI breaker located? Is it a 120V breaker or a 240V breaker in the panel that's a shared neutral circuit? The latter would explain how so many loads and rooms are on one 15A circuit. That wiring on a 15A 120V circuit would not have met code 30 years ago for a single 120V circuit. Three bathrooms on a single 15A circuit, one hair dryer uses up 80% of that .

Anything else change in the areas with the problem? Nothing new has been plugged in that you're not aware of? If nothing has changed, then it's some new defect in the wiring, switches. receptacles, loads, etc. If some new load was plugged in and is present, then it's that new load or that the wiring where it's plugged in is wrong, eg the neutral connection at that receptacle is wired to the neutral of another circuit or ground instead of the GFCI neutral. That would not trip the GFCI until some load was plugged in. Jim's suggestion of using a plug-in circuit tester is a good one, it will show those things, I would use one on all the receptacles as a next step. And like Jim said, you're on the right track, you need to find points where you can keep dividing that problem branch to find where the fault is.

I did add an outlet in a steel box in the closet to power a WiFi router but the GFI breaker didn't trip for a week after my addition and it occasionally tripped even before I ran the new 15' Romex line. And it was constantly tripping even after I disconnected the new line that I added. I believe that proves that my addition didn't cause the problem (although I wish my project DID cause the problem because the problem would be resolved already!). I've decided that the next troubleshooting step will be to open up the two ceiling lamps in the guest bedroom to try to find the other end of the feed from the closet ceiling light. Hopefully, I can finish restoring power in the master bedroom today.

Any nails or screws driven in the area recently??a puctured power cable could provide a ground fault.

It might have still been code compliant in the early 90s. Somewhere around then or mid 90s the requirement for 20A circuit for the bathroom receptacles was added. But then that's the national code, states can take a few years before they adopt it, etc. But even if it was code compliant, putting all that on one breaker was never a good idea.

Is it possible there is another receptacle or light outdoors on this? They sure put a lot on this circuit, it was common to put those on the same circuit as bathrooms to share the required GFCI. And outside wiring is a very common source of GFCI trips, some moisture gets in it. If there are outside receptacles I would check those as a high probability source of the problem.

Thanks to all for information and advice provided, especially to Jim Joyce and Trader_4. Today I got everything working again. I even swapped back the original GFI breaker, which I thought was no good since the house is 30 years old. (But I plan to keep the replacement one for a couple of weeks before returning it, just in case.)

For the new Romex I added (providing power to my WiFi router in the closet), I had failed to properly affix the bare grounding wire to the originating box. After fixing this, everything tested good to that point. However, after connecting the feeder cable running from the bedroom closet to the guest bedroom, the GFI breaker tripped again, which convinced me that the problem was in there. But today, after reconnecting the cables in the guest bedroom, it all worked. I wonder if I might have reduced resistance in one of the original connections in there.

Since everything is working now, I did not investigate which circuit the outdoor outlets are on. I’m glad I took on this project. Not only did I save a lot of money but I learned a lot too. And I suspect that the new skills I learned will be useful again in the future.