AFCI Trips Randomly

[SlappyWhite]

My guess in this specific case.... The AFCI breaker will trip on a ground fault of ~50ma (compared to GFCI at ~5ma). Assuming the smoke alarm consumes less than 6w there is not enough current from the fault at this specific location to trip it based on the ground fault. When other devices are turned on some current will find its way through that fault and trip it. Could have been a borderline fault current wise at the detector and the new breaker is a little more sensitive. As I noted before in the thread (post #8) I have had this happen (neutral to ground fault, in my case a bad cable/wire). In that example turning on one or two lights didn't trip it...

If the new breaker happens to be dual function it will now trip based on GFCI levels... so right away.

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I always wonder how many cases of "AFCI are black magic and the devils spawn" there is actually a small fault or loose connection (like loose backstabbing) that is beyond the skill or patience of the troubleshooter to find and how many are actually bad breakers, devil's spawn, etc. In this case the OP found a fault, the AFCI in the end did its job.

 

[dscheidt]

I always wonder how many cases of "AFCI are black magic and the devils spawn" there is actually a small fault or loose connection (like loose backstabbing) that is beyond the skill or patience of the troubleshooter to find and how many are actually bad breakers, devil's spawn, etc. In this case the OP found a fault, the AFCI in the end did its job.

Lots of them. Most people won't spend (or pay for) the time it takes to track something like this down.

Early AFCI really did ****, but current stuff is pretty good, and most faults are real.

 

[bad_idea]

I replaced the breaker with a CAFCI breaker. Lowe's didn't have a AFCI breaker on the shelf. I did a very quick inter web search and found the CAFCI does AFCI and something else too.

 

[AntonLargiader]

CAFCI does both types of arc fault detection: Series (open arc) and parallel (shorting arc).

Good job on the fault finding. That AFCI breaker led you to find actual problems.

 

[SlappyWhite]

AFAIK NEC, CEC, etc. require combo now for new installs so I doubt anyone still makes the older gen AFCI as CAFCI can replace it for repairs. Might be some old stock still kinking around??? The change to CAFCI in this thread does provide some explanation as to why the new breaker tripped more consistently than the old. The old one was likely not bad (defective), just not as good as the new one....

But the key take away for me... there was a fault and the breaker detected it. The trips were not due to black magic, devil's work, snake oil...