Circuit Breaker Tripping

OK I know this isn’t an electricians forum but all this smart home stuff pretty much requires that we know a little about electrical wiring so … I’m hoping someone might have some insight into this problem. Note this is completely unrelated to smartthings - no smart devices in the circuit that is giving me trouble!

So, I bought my house 2.5 years ago. The house is ~25 years old. I’m the third owner. The second owners finished the basement, mostly, I think, a DIY job. The wiring is … interesting. Most of the lights, 18 cans and a couple of others, are on a single GFCI breaker, plus the outlets in the room that was finished as a bedroom. This breaker periodically, randomly trips. I can discern no pattern whatsoever to what might trigger it - not time of day or time of year (which could suggest some heat related issue), not any particular switch or outlet w/in the circuit, which could point to bad wiring in that device. I’m at a total loss. An electrician who did some other work for me said the issue is either the breaker itself being faulty, or a bad connection somewhere in the circuit, which can only be found by checking the wiring at every location. This makes sense to me EXCEPT for the really flaky behavior - I would think that bad wiring would behave in a somewhat consistent way, and especially that you would only see the issue when the switch or outlet w/the bad wiring was in use.

Any ideas?

Bring in an electrician. :sunglasses:

Flakiness of this type is common when you have a set up that complicated. It could be that you’re reaching a maximum load, or could be just some specific combination of devices drawing, or even the sequence in which they draw, which is causing the problem. But it’s something that you need the right tools and knowledge to diagnose, and it’s definitely something that you want to correct.


Did you try the breaker.? Is it a ground fault breaker? I had a case in my last house where a breaker would trip randomly as you describe. In my case I thought it might be some of the GE Z-wave switches I had installed. I checked them several times and could not find any thing wrong with how they were wired. I finally just decided to change the breaker and that fixed it. The house was about 10 years old, I actually had to swap three of the ground fault breakers in that house. Two were obvious they tripped and would not reset, the third was the random/occasional trip.

It’s a fairly inexpensive and easy thing to try. Provided you feel confident messing around in your breaker box.

same for me, i have an extension the ground trip at the house end would go randomly, where as the extension box was fine. 1st thought was the cabling to the extension or a combiled ground leakage. i swaped the trips bwtween the house box and extension box and (touch wood) not done it since. if you want to invetigate you would need a clamp current meater capable of reading 1mA the trip fire at 13mA normaly. Then test the earth cable running from your problem area to see is there is any current. As these sense a differance in curent between L and N, this still might not work as the seapage could be from an appliance to ground, eg a washing machine could ground out through the plumbing

18 cans of light fixtures seem a little much, plus you have even more stuff on top of that. You should get an electrician in there to have a look but before you do you can try;
Add up the wattage of each bulb to see if you are reaching the rated load of the circuit.
If you are, you could remove some of the bulbs to lighten the load, If the problem abates then you can let the electrician know.
If you you find that all the lighting cans are less than half the load it could be possible the GFI breaker is bad. It happens, I’ve seen it. IF YOU KNOW WHAT YOU ARE DOING and have another GFI breaker in the box of the same load rating you could swap the breakers to see if the problem moves to the other circuit or stays the same. Again, more information you can convey to the electrician.

Basically you are doing a little investigating beforehand. If its a defective GFI buy a new one and you’re good to go. If it is a load problem you could reduce the load but that isn’t really solving the problem so call a professional. If its neither a load or a faulty breaker, call a professional.

Good Luck

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I agree with the other who indicated it could be best to “call a professional” unless you are quite familiar in working in a breaker box. One other thing that I have seen is the wires connected to the ground bar (neutral and ground) can become loose over time. This can create intermitent failures. You can attempt to tighten these connections which could solve the issue. But be careful of arcing the screwdriver between one of the breaker terminals I have also experienced the bad breaker issue noted by several other posters and you can try to replace the breaker to see if it fixes the issue. In most areas you can get an electrical home inspection for less than $100, that may be well worth the money.

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18 cans and outlets on a single circuit? Is this a 15 or 20 amp breaker? What wattage bulbs are in those cans? How many things are plugged into the outlets and how much wattage are they using?

Actually 17 cans, all incandescent bulbs, 65W each, plus a couple of “regular” lights, so around 10A if every light is on! However, this basically never happens, and, as I said, the tripping of the breaker is very random - I have not been able to identify any pattern or particular set of lights that, when on, will definitely cause the breaker to trip. In point of fact I had them ALL on over the weekend, for at least 30 minutes, w/no problem - and in the past I’ve had just a couple on and the breaker tripped multiple times w/in a few minutes.

I’m not happy about the wiring, and since I recently had some water damage and had to rip out some drywall in the basement I’m hoping I can split this out into two relatively balanced circuits, but that still doesn’t resolve the issue of the random trips.

Does anyone know if breakers can be prone to failure at low temps? If anything, the one pattern that might be discernible is it seems to happen a lot more in the winter. It happened multiple times this past winter, but hasn’t happened once this summer.

BTW, don’t worry, I have a VERY healthy respect for electricity … I have done a fair amount of electrical work in the past so I think I can do this job, but I always dbl and triple check that power is off before I work on anything, and I won’t touch anything in the breaker box w/out turning off the power to the house!

One of my engineering professors used to say “electricity is physics, not math.“ Meaning it’s not binary stable state, not just on and off and you add the on’s to see where you are. It ebbs and flows and “fully loaded” 20 minutes after everything is on is a different number than fully loaded one minute after everything is on. And it may be different depending where you are in the AC cycle.

And the more devices connected to the circuit, the more variability.

So it’s not surprising that it’s happening unpredictably. There may be weather factors, including humidity and temperature, but maybe not.

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What about things plugged into outlets? They could be on the same breaker.
Stop by Costco and get some LED bulbs there. By me they are dirt cheap there. That will lower the load tremendously.

Is the breaker an arc fault GFI breaker by chance? I now have 2 in my panel as a result to an addition and them now being required. Sometimes mine trip with a brief power outage. Another tripped when I had a CyberPower UPS in that circuit for my bedroom AV equipment. After researching I learned the CyberPower circuitry isn’t the best and once I removed it problem went away.

Actually I think I already mentioned the outlets in the bedroom are also on the same circuit as the lights (!), but there isn’t actually anything plugged into them. And yes I could replace some of the bulbs w/LED’s (or all of the bulbs) but it kills me to waste perfectly good bulbs … and anyway, as stated previously, the trips are random and don’t actually seem to have anything to do with how many lights are on.

It’s not an arc fault. If I replace it (and I suspect I will wind up doing that) I was thinking I’d replace it with an arc fault. Good idea? Bad idea?

I am no electrician but they are required by code these days, at least in my area. After never having them until the last two years, I personally don’t like them. I have never had another breaker trip like these do.

You could have a loose wire somewhere along the chain causing this. Only way to determine is to open each outlet and light.

That is pretty much where I’m at.

So 17 “cans” @65W each = 1,105 watts…… /120volts = 9.21amps Not enough to trip a 15/20amp “breaker” . Just to be clear on what we are talking about… Is this a GFCI breaker (Ground fault circuit Interrupter), leg off a GFCI outlet or an AFCI breaker (Arc Fault Circuit interrupter)? I am not sure why your lights wound be on any parts of a GFCI system… A lot of the new building codes requires AFCI breakers for all of your 15/20 amp outlets. Most electricians are now using 14/2 romex (white) on your lights with a 15amp breaker and 12/2 romex (yellow) with a 20amp breaker on all your outlets… I am assuming this all single phase residence in the US?

This is a GFCI breaker, not an arc fault, and not a GFCI outlet. Yes, agreed, very weird to me that the LIGHTS are on a GFCI but the OUTLETS are not. But there are many weird things about how this basement is wired up. Per above, in addition to ALL of the lights in the basement being on this breaker, the outlets in the bedroom are … so maybe they thought they were doing it right by putting those on a GFCI breaker?!

Yes, this is single phase, residence, in the US.

As I’ve hinted, there are other weird things about how this is wired. I am at work but will post the details tonight. Kinda wish I could just rip out all the wiring and redo it the right way but that’s too big a project!

OK here are some more details, hopefully I can explain this in a way that makes sense and isn’t too hard to follow.

When I bought the house the inspector noticed that two wires were connected to the hot terminal on the GFCI breaker that controls the problem circuit - a red wire and a black wire. We put this in as something the owners needed to correct and when I checked it before closing, there was only one wire there. At the time I wondered how they fixed this - seemed like this could be a big fix - but I didn’t dig deeper (and I really wish I had!).

Fast forward to now, and the other day I pulled the cover off the panel and realized a couple of things:

  1. The breaker immediately above the problem GFCI doesn’t have anything connected to it. Weird.
  2. It looks like they “fixed” the two wire issue by putting a pigtail on the breaker and wiring the pigtail to the two wires that had been connected to the GFCI, and hiding this behind the other wires in the panel (see my previous comment about wishing I’d dug deeper when I bought the house).
  3. There is another white romex in the panel that isn’t connected to any breaker and is labeled “spare for basement”.
  4. In the basement there is a junction box that just contains some wires twisted together. The power from the GFCI comes into this box and is wired to two other lines - both wired to the neutral from the panel, and then one hot (black) wired to the hot (black) wire from the panel, and the other hot (black) wired to the hot (red) from the panel. So, they used the three-wire romex from the panel to power two separate circuits in the basement by using the red and black wires in the romex to carry power from the panel.
  5. I verified that of the two romex connected to the panel as described in (4) above, one powers the bedroom (all lights and outlets), and the other powers the rest of the lights in the basement. As previously mentioned, the rest of the basement outlets are already on a separate breaker.
  6. There is an area in the basement that looks like it was meant to be a wet bar or at least a spot you could put some cabinets and maybe a mini fridge or something; in this area there are some blanks on the ceiling and wall and a switch that doesn’t control anything. I assume they meant to put something in here so had power run but didn’t finish the project.

All of this is very weird and I have many questions, and a few theories.


  1. Why did they connect power to the two circuits in the basement (bedroom and other lights) through two hot lines (red and black from the panel) instead of just tying them both to the black, like you’d normally see?
  2. Given that there is an unused breaker RIGHT NEXT TO the GFCI breaker, why didn’t they drive power to one of the two circuits above through this breaker, thus splitting up the load in a more reasonable way?
  3. Why is there an unused and apparently unconnected line in the panel, and where does it go?


  1. The bedroom is all of this one line; I am thinking they meant for this to be a separate circuit.
  2. Either someone screwed up when wiring everything up at the panel, or there was some problem I can’t identify, that resulted in them connecting both circuits to the single breaker rather than splitting them up (maybe the blank breaker failed and rather than replacing it they just put them both on the GFCI?).
  3. I am guessing that the unused romex may go to the unused blanks where I suspect they were going to put in a wet bar. Since they never completed the project they never hooked it up in the breaker box. Also, maybe this is why there is an unused breaker, and why they ran the other two circuits to one breaker - they had planned to connect the unused wires to the unused breaker, but never got to it.

This all suggests several things to me:

  1. I need to check what’s behind the blanks and see if they do, in fact, connect to the unused wire in the panel. This would at least resolve that mystery … and since I too would like to put a wet bar in there, I will need to connect that to power at some point.
  2. I can resolve the code violation of the pigtail, and split up the load on in the circuit, by connecting the red wire to a separate breaker rather than driving red and black from that breaker. I am wondering if this might also solve my random tripping issues.
  3. I feel like I should still check all the connections in the circuit to make sure I don’t have a lose wire somewhere that is the real culprit of the random trips. I just don’t feel like I can totally trust the wiring at this point, and this could unequivocally eliminate bad wiring as the source of the problem.
  4. If I do anything in the panel I should probably use this as a chance to correct the weird GFCI usage … the outlets and unfinished storage room aren’t protected, while the lights and outlets in a finished room are. This seems backwards.

OK, that was LONG. No idea if anyone will find it worth reading, but given the questions, seemed like I should provide all the details. If you got this far, thanks, and any input on something I may have missed is always appreciated!

You can run two circuits on a three-wire, using the neutral for both. Not sure how popular that is any more, but it’s possible. In the breaker box, though, the black should have been connected to one breaker and the red to another breaker, providing two 15/20 amp circuits. This might explain why you had the “empty” breaker . . it was meant for the red conductor but incorrectly wired to the breaker the black was connected to.

If you follow that 3 wire you might find that it is ultimately feeding two circuits. If that’s the case, if I understand correctly, moving the red to the other breaker might solve your problem as it will take a portion of the load off the “doubled up” breaker. That’s presuming that an overload is causing the trip, which as others have discussed, might not be the case.

You must not have read all of my novel … :smiley:

I did trace it out and it is in fact feeding two circuits, the bedroom lights and outlets are on one circuit, and the rest of the lights are on the other one. It sure looks like they meant to wire it on two separate breakers; just weird that they messed that up.

Correct, lol.

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