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puzzled by afci

Posted by abchoppers (My Page) on
Fri, May 14, 10 at 15:31

My friend has a garage apartment with a 100 amp subpanel. Recently the tenant has stated that the light circuit, protected with an afci breaker, trips whenever one of the burners on the oven (on a completely separate 50 amp circuit) is turned on.

My thought is that the burner being on is only a coincidence, and the problem is in the light circuit only. A few months ago the tenant said that same light circuit was tripping, turned out the problem was a dead bulb on one of the track lights. It fixed it immediately when we took the dead bulb out. My questions:

1. Do you think it could just be another dead or loose bulb?
2. Is it possible the oven has any effect on the separate AFCI light circuit? I just don't see how.

Also, we are not planning on doing any work in this rental, just looking for obvious like a loose bulb, anything more extensive and an electrician will be called. Thanks for any help.

Follow-Up Postings:

RE: puzzled by afci

1. Unlikely, if the oven correlation is strong..

2. Yes. Stranger things have happened.

RE: puzzled by afci

I don't know how strong the correlation is to the stove burner, I'll be going over tomorrow to help my friend and I'll find out. It just puzzles me that all the lights are on one afci breaker, yet only these lights cause the breaker to trip. Also puzzling is how only one burner on the stove has an effect apparently. The set of lights in question are over the stove in the kitchen, I believe it's just a coincidence that she uses those lights when cooking.

I just thought I'd post and get a potential heads up before my friend and I looked around, this way if we have to call a pro we'll have some idea. I just don't see how the stove could be related.

RE: puzzled by afci

AFCI devices look for the high frequency noise produced by an arc.

It would probably be possible to couple enough noise from an arc in another circuit to trip another circuit, especially a noise source circuit that is larger.

RE: puzzled by afci

Thanks for the replies.

So it's possible that the one burner in the stove has a short, causing that 50 amp circuit to trip. In turn, the AFCI breaker trips from the noise of that. Could it be possible that if the AFCI breaker is next to the 50 amp in the panel, this could be why it's so sensitive to the noise? There are 4 other AFCI breakers in there unaffected.

Also, if what you say Brickeye is correct, than probably the stove should be tripping its own breaker without the AFCI protected light even on. I'll have to try these scenarios out tomorrow.

RE: puzzled by afci

"Short" is not a synonym for "something wrong." If the burner had a short circuit, it would trip the breaker immediately. You have a different kind of problem.

One possible fault that could cause electrical noise would be a failing control on the range. Another possibility is a loose connection in the wiring feeding that surface unit.

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