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One of my circuit breakers (20 Amps) handles about 10 light switches in my house and nothing else. For the last couple months or so, it trips about once a week, but never in response to turning an additional light on (i.e. ~5 of the lights will be on, and then all of a sudden the breaker will trip).

Each time, I reset the breaker (without turning any of the lights off). All of the lights go back on, as they were before the breaker tripped, and the breaker doesn't trip for another week or so.

  1. Why is the breaker tripping on its own? I would expect the breaker only to trip if I turned something on (e.g. flipped another switch) that drew more current through the circuit. In other words, if the set of lights that were on at 5pm were not enough to trip the breaker, why would they be at 6pm?

  2. Why can I flip the breaker switch and make everything work correctly again? In other words, if some set of lights tripped the breaker at 6pm, why would the same set not trip the breaker at 6:01pm after I reset it?

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    anything unusual about this breaker? Does it have a TEST button? When the breaker trips, does anything other than lights lose power?
    – Harper - Reinstate Monica
    Commented Jan 5, 2021 at 21:28
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    All the things that Harper asked and the once a week is there possibly a refrigerator/ freezer on this circuit ? The defrost timer ?
    – Ed Beal
    Commented Jan 5, 2021 at 21:59
  • Is it an AFCI breaker? These've presented no end of trouble in our new-construction home, and the best idea the electrician has had so far is "get rid of them". Of course, the electrical industry has forced these to be required by code now; getting rid of them isn't so simple. In some cases, we've identified a particular appliance that trips the breaker (typically ones with motors that have brushes, or that have some kind of power modulation like a fancy toaster oven), but lately there are four breakers that just trip randomly, even when their circuits don't have anything switched on.
    – Peter Duniho
    Commented Jan 5, 2021 at 22:12
  • @PeterDuniho Because builders love to use backstabs for switch and recep connections, because they're fast to install... and they are notorious for failing open, which means they are prone to arc faults.
    – Harper - Reinstate Monica
    Commented Jan 5, 2021 at 22:18
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    Yes, is there a TEST button on this breaker?
    – ThreePhaseEel
    Commented Jan 6, 2021 at 0:33

1 Answer 1

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Bad bulbs bad bulbs, what you gonna do?

Some of the funky new bulbs got stuff in them. This question covers that. Why is my lighting circuit tripping the breaker?

I do not pretend to understand what that stuff does but I do know that failing LED bulbs can display a variety of fascinating behaviors not seen with older bulb types.

It will not be expensive to replace all the bulbs in these lights with new bulbs. Not expensive because you can save the old bulbs. If issue persists despite changeout then you have a lot of spare bulbs you will eventually use since you have a lot of lights.

If all new bulbs fixes the issue then you know it was one of the old bulbs. Test them one at a time on a lamp in a special penalty box circuit that is not being used for anything important. When you find the bulb that trips that circuit, it goes in the trash and the rest can come back into the game.

Psychically putting myself in your home (your beer can collection is sweet!) and examining your bulbs, I found two LED bulbs that looked suspicious. Different than the brother bulbs. I was only there psychically so could not remove them for you, but if it were my house I would start with changing out those funky looking ones first before changing them all.

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  • AFCI’s have a problem with electronics that modify the wave shape. Since dimmers, electronic ballasts and led lamps all have wave shaping electronics they are known to cause issues. This plus motors with brushes, and variable speed motor controllers and contactors that pull in heavy loads are all things that my state has allowed the AFCI to be removed and a standard breaker used. There may not be anything wrong with the light itself. I believe the link is an overcurrent issue not the same as this question.
    – Ed Beal
    Commented Jan 6, 2021 at 15:24

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