Square D Homeline panel and breakers of recent vintage, with plug-on neutral. Most breakers, and all of the problematic ones, are AFCI+GFCI combo.
There are four breakers in the house panel that occasionally — once every two or three days — will trip for no apparent reason. Most of the breakers are fine. It's just these four. They don't all trip at once. It's random which one actually trips, and most of the time only one will trip. The one time more than one tripped, they didn't trip at the same time, but the second tripped less than a minute after the first.
I also have two rooms with electric floor heat (SunTouch) controllers that have a built-in GFI feature. The GFI in these controllers also trips, on roughly the same random interval (but again, not in concert with each other or any other breaker).
I only just recently learned that each Homeline breaker, in spite of not having an indicator, does have a way to report what the fault that tripped it. Found it on a post here, actually. Using the "Time Saver Diagnostics" feature, I have found that the breakers are tripping because of a perceived ground-fault. This is consistent with the floor controller behaviors as well.
I also have swapped the most frequently-tripping breaker with one that is just AFCI, without the GFCI feature. The AFCI-only breaker does not trip. Again, this is consistent with the ground-fault detection being the problem.
The one electrical appliance that seems consistently associated with the tripping is the well pump (submersible, 1 HP, Subdrive controller). When a breaker trips, it seems that it only happens when the water is running. Granted, it's a busy household and the water runs a lot. But I've had a couple of moments in the middle of the night when everything is quiet and a GFI trips (breaker or floor controller) just after I run the water (e.g. flush the toilet).
Note, however, that the breaker for the well pump itself never has tripped. The breakers that do trip are entirely unrelated to the well pump. In many cases, they trip even when there's not even an electrical load on them (one is for a lighting-only circuit and will trip even if the lights are off).
Attempts at "diagnosis" so far
Frankly, not much, at least not in terms of creative problem solving. Though I have certainly spent a lot of time on the problm.
We have been having problems with breakers generally for a couple of years (since we originally moved into the newly-built house). Mostly, the problems were related to AFCI tripping, i.e. trying to operate certain appliances and having the breakers for the circuit the appliance is using tripping.
The electrician who originally did the wiring for the house took a long time to get around to fixing that, but they did eventually show up about six months ago to put in new AFCI+GFCI breakers on the circuits where we'd been having the most trouble.
After that, the tripping for appliances seemed to stop, but this problem with the GFCI tripping appeared. Unfortunately, this new problem was more disruptive than the old one. The electrician never did take the problem seriously, only visited the house a couple more times to work on the problem, and mostly all they've ever tried was swapping old breakers for new.
The one exception to that was that they heard from someone else that sometimes this sort of tripping happens because of issues with the utility power and that installing a surge suppressor in the panel would help. So they tried that and now I have a surge suppressor but it didn't help.
That electrician has refused to do anything more to try to fix the problem unless I start paying for their time, in spite of the fact that the problem only started after work they did here. That electrician is no longer working for me.
Messing with the panel changes the problem
And indeed, seems to have caused the problem in the first place.
As noted above, I only recently discovered I could "ask" the breaker why it tripped. But since then, all of the data from the breakers point to ground-fault tripping, which is different from what was almost certainly arc-fault tripping that was taking place prior to six months ago.
Which means that the ground-fault problem is new, and started immediately after the visit from the electrician to replace the breakers because of the arc-fault issues we'd had before.
Similarly, while we'd had some problems with the floor-heat controllers before we moved in, they had settled down (for whatever reason) by the time we did, and we didn't have a single spurious trip from either controller for the first 18 months in the house. It was only after that visit from the electrician six months ago that the floor controllers started tripping again.
In addition, we have gone back and forth a bit between seeing tripping occurring multiple times a day, to seeing the tripping occurring only every few days. Every time this pattern changes, it happens only after someone has been changing things in the panel (i.e. swapping breakers). This has been true whether the person swapping the breakers was the electrician or myself (I volunteered to do some of the diagnostic-swapping, so that the electrician wouldn't have to drive out to the house so often).
Changing the breaker doesn't change the problem
Even though the tripping occurs only for breakers in specific panel slots, it doesn't seem to matter which breaker is in which slot. I can swap a breaker from a problematic slot and a not-problematic slot, and the problem stays with the slot, not the breaker.
I have tried to ask a few other people about this already
- Square D. I tried using their online form to contact them, and got no reply. I have not yet tried to call them.
- Our well drilling contractor. He's extremely competent and experienced, but had never heard of a problem like this. He's going to check with the pump manufacturer in case they have, but I'm not optimistic. This seems to me like the well pump is mainly just an innocent bystander that happens to trigger a problem that exists in the wiring.
- Another electrical contractor company. After hearing my sob story, they declined to work on the problem, telling me I should let the original contractor continue to investigate (which I'm definitely not going to do). I guess I scared them off. :(
What's going on? What should I or another electrician be looking for?
I feel like by now I have a lot of data, which should provide a lot of clues, and yet that original electrician refused to do anything except just keep swapping parts. Because of the correlation with the work that had been done, I asked them whether it could be a problem with the panel itself or possibly even with the work, but they said it was impossible.
I can't shake the feeling that this correlation shouldn't be ignored. But I also have no idea what the correlation could mean. I feel like the solution is probably somewhere in the panel itself, but I can't be sure of that, and even if I could I have no idea what to look for.
Given all of the information I know, what is causing this problem? If you know for certain, that's great, but any reasonable speculation that can assist me in a final diagnosis is welcome. Alternatively, additional diagnostic steps that I haven't taken yet would be welcome as well.