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Intermittent breaker tripping

A 15-amp breaker is tripping intermittently. It carries 9 light fixtures including a ceiling fan/light, an exhaust fan/light, and 3 outdoor lights. Started trippng after replacing the 3 outdoor light fixtures w/ new motion sensing fixtures. All connections on the new fixtures were checked & appear good. Can go days w/o tripping, then trip for no apparent reason. Where to start?

Re: Intermittent breaker tripping

Sounds like you may have an overloaded circuit. Have you added up the watts of all the loads? A 15A breaker should only be loaded to 1440W if the loads will be on over 3 hours.

When the breaker trips is it warm to the touch?

Also, when an incandescent lamp first comes on, the surge can be many times the lamp rating so.. if the circuit is already near overload that may induce the trip.

Good Luck from Columbiana, Alabama
Maurice Turgeon, http://thesemi-retiredelectrician.com

Re: Intermittent breaker tripping

I agree with Semiretiredelectric. Some of the fixtures must be rewired to another or a new breaker.

Re: Intermittent breaker tripping

I concur - but since you mentioned outside lighting, is there any way the outside fixtures / circuits can be getting wet? I'd check the connections on the "new" fixtures

Re: Intermittent breaker tripping

I would agree with houstonremodeler.... but usually standard circuit breaker don't detect "wetness"... that would be a GFCI Breaker..... and by the way.... you should consider getting a GFCI breaker put in because it is in a wet location... but check with what semiretiredelectritan said.... calculate your load of the wattages... To do that remember: if anything is in kilowatts multiply it by 1000 it get the watts.... good luck (you probably don't need to convert kilowatts to watts, but i just thought just in case.):D

Re: Intermittent breaker tripping

Breakers do go out of calibration. I've had breakers trip randomly with no apparent overload or short circuit; replacing the breaker fixed the problem. I've also seen a breaker overheat (probably due a failing contact internally) and fail to trip.

If you've verified that the connections are good, that there is no apparent short circuit, and that you're not overloading the circuit, replacing the breaker is a fairly simple exercise.

The cost depends on the model of electrical panel. If it uses "current production" breakers, the cost of a replacement will be $3-10. If it's an obsolete panel, the cost could be as high as $50 (Pushmatic or Zinsco are horribly expensive).

Make sure you only use a breaker that's "listed" for your panel. The label inside the door should tell you what type of breaker can be used; usually it's a type-code of one to three letters. See the compatibility guide on this page -- ignore the "UBI" prefix (example: Zinsco is listed as "Type UBIZ" but it's generically known as "type Z".)

Another caveat: if you have a tandem breaker (two breakers in one housing without linked handles), bring the breaker in to the store and make sure the parts where it mounts to the panel are the same. There are subtle differences that can prevent a breaker from fitting.

Re: Intermittent breaker tripping

All good advice. In reading over the chart Fencepost linked us to I noticed they mentioned turning off the main breaker, which was good.

They also mention, some service entrance panels don't have a main breaker so the buss or stabs will always be "hot", unless the meter is pulled or there is a main disconnect outside. Extra caution should be observed while replacing breakers, in these panels as old and brittle breakers may crumble in your hand as you try to remove them.

Also, last week I was called in to investigate why a cutler hammer breaker was arching and dropping out power to an air conditioner. Well it was supposed to fit in a GE panel but would not seat fully. When replaced with a GE everything was fine.

Also, I've found if the blades on most breakers are lubricated (No-Lox) they seat better and last a lot longer, especially GE which will bend over, if this is not done.

Good Luck from Columbiana, Alabama
Maurice Turgeon, http://thesemi-retiredelectrician.com

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