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Discussion Starter · #1 ·
Hello,
I recently ran a new circuit to a bedroom. Installed an AFCI breaker on the panel and worked fine. I ran another circuit to another bedroom and installed an AFCI breaker. There was nothing on the end of the run. I had not installed a receptacle so that I may test the voltage as I did with my first run. I turned the AFCI breaker on, it stayed on. When I pressed the test button the breaker tripped as it should but I saw a bit of a spark. I turned the breaker all the way off and back on and the AFCI breaker started to smoke. I immediately turned it off and removed it. Why would the breaker smoke if there was nothing drawing power from it? The wires were completely apart. I can only assume a bad breaker but before I try another AFCI (at 40 dollars a pop) I would like to know if anyone knows what may be happening. Thanks for your time and input.
 

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GC/Master Plumber/Mech
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New parts right out of the box are rare but it happens.

Disconnect the black wire from the breaker and try it again. It really sounds like it is defective.
 

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Discussion Starter · #3 ·
Thanks for your time Plumber. I forgot to mention. I did not immediately removed the breaker. I turned back on after a few minutes, it stayed on with no smoke but the test button would not trip the breaker. I figured it is fried. Thanks.
 

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Discussion Starter · #5 ·
Yeah, I know it is fried. I am just afraid of burning another one. Can't figure out why this one did not function properly especially with no load. Thanks for your time.
 

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Even if the wires where shorted that should have only tripped the breaker. Defective breaker. It's one of the wonders of the new solid state circuitry. The little Chinese lady that soldered it probably got a solder blob where she shouldn't have.
 

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Discussion Starter · #7 ·
Yes, that is the way I see it too (not the little chinese lady just the defective part). I will just have to put another one up and see what happens. I have no choice. Thanks for your time.
 

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All electrical things operate on smoke. The electricity is only needed to keep the smoke from getting out. :whistling2:

Once the smoke gets out, it is no good. :laughing:
 

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Why would the breaker smoke if there was nothing drawing power from it?
An internal defect in the electronics circuitry of the AFCI.
Failing by shorting = smoke.
Failing by opening = no function, no smoke, no nothing.
Regular breakers don't have circuitry across the input lines, only a 2W resistor in series with the hot line.

I'd guess a working AFCI would draw 10 mA or so all the time just to power the innards. You could confirm this with a DMM on your other AFCI. Start on the high amps scale and work down.

If the thing is not returnable you could autopsy it and look for a charred component. Depending on what smoked you may be able to replace that component for a buck or so. Maybe.
But then you should only use this repaired AFCI for testing and whatnot.

Building a test setup to weed out bad AFCIs that fail in this way without smoking them is a bit complex.
 

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Discussion Starter · #11 ·
Thanks for your time Yoyizit. Very informative. My hopes are that it is a defective AFCI breaker. I just don't want this to happen again. It can get very expensive. I am installing the new one soon and will see how it goes. Thanks again.
 

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Thanks for your time Yoyizit. Very informative. My hopes are that it is a defective AFCI breaker. I just don't want this to happen again. It can get very expensive. I am installing the new one soon and will see how it goes. Thanks again.
Hook up the new one to a 120v cheater cord. That way you don't put labor into a potentially bad unit.
If it's OK with no load, then load it with a 100w bulb.
Run it through its paces with the cheater cord first. You could even check for arc detection by making a loose downstream connection. Some guy on this forum did that (with mixed results).
 

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Bocolo - You might also just try your new circuit with one of your exisiting breakers. Just swap the hot wire over to whichever one you can reach easily. It's unlikely, but just in case there is something wrong with circuit (like a drywall nail) through the romex, you'd find out quickly. The AFCI should simply have tripped like a normal breaker, not started blowing smoke rings, but these days......seems more and more of the electrical problems I deal with turn out to be due to multiple faults.
 

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Discussion Starter · #18 ·
It was a bad breaker. I connected a new AFCI breaker last night and it worked fine. Press the test button, passed the test several times. No smoke this time. Although when I tested the line it gave me 119.7 volts with the breaker on, 150.1 mv with the breaker off, and 172.0 mv with the breaker off the panel but the wires connected to the breaker. The other AFCI breaker when is turned off gives me 52 volts which I am assuming is a phantom reading. Or is this too high? Thanks for all your time and input.
 
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