# Arc fault breaker troubleshooting



## MTW (Aug 28, 2013)

Remove the AFCI and replace it with a GFCI breaker for a test. If it trips, you have ground fault on your hands. I would also megger the wire.


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## Woodsman (Feb 21, 2011)

Good idea with the megger, I'll see if I can get one from the shop Monday. I'll also look into the gfci.


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## IEC (Sep 20, 2015)

Woodsman said:


> I'm looking for help or advice on troubleshooting a lighting circuit in a residential remodel. The circuit is fed from a 20amp arc-fault breaker which supplies kitchen, family room, and front porch lighting. I believe I have narrowed the problem down to a switch leg at the end of a 3-way. When I disconnect the switch leg, the breaker seems to hold just fine but once I tie the switch leg back in for the outside porch lights the breaker will trip anywhere from 30 seconds to a little over a minute later.
> I have already swapped out the breaker and the problem still persists. The switch leg is behind Sheetrock and tongue and groove panels so I am really trying hard not to rip anything apart.
> Any good ideas for me to try or check?


Look for condensation in the porch light housings. Sometimes the heat of the lamp can create condensation that doesn't dissipate in the socket area/junction box (if a can light) which will trip the AFCI. This can also happen where the porch is open to the attic space itself - the outside temperature is dramatically different than the attic, so the dew point forms and condensation occurs. 

Another thing you may want to inspect are the lampholder (socket) lead wires. The heat of the lamp combined with the cheap wiring most sockets come equipped with can make the socket wires brittle and split, which can read as an arc fault. 

Also, make sure some yahoo isn't using the neutral as a ground. That too will trip the unit.


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## chicken steve (Mar 22, 2011)

Woodsman, does the noodle flow through the 3W to the switch and light, or is it a _'dead end 3W'_ w/o one ?

And/or, are there any high end electronic dimmers /motion detection, etc?

~CS~


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## don_resqcapt19 (Jul 18, 2010)

Disconnect the loads on the switch leg, just leaving the wiring connected. If it still trips, you have a problem with the wiring or a hidden load with a problem.


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## ELECTRICK2 (Feb 21, 2015)

MTW said:


> Remove the AFCI and replace it with a GFCI breaker for a test. If it trips, you have ground fault on your hands. I would also megger the wire.


Both good ideas, but I'm dreading the service call for an AFCI that keeps tripping. You replace the breaker and check all connections etc. on the circuit. AFCI still trips. What do you tell the home owner?


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## Frank T (Oct 3, 2015)

try a new light?


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## Frank T (Oct 3, 2015)

disconnect the light and see what happens


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## IEC (Sep 20, 2015)

ELECTRICK2 said:


> Both good ideas, but I'm dreading the service call for an AFCI that keeps tripping. You replace the breaker and check all connections etc. on the circuit. AFCI still trips. What do you tell the home owner?


You tell them that they have an existing issue conflicting with Code's current standards (a CAFCI) that requires you to work in sequence to eliminate the possibilities by their level of probability. You further explain that the systematic approach is the opposite of the usual "throw darts at it until I hit it" and should not be confused with it and that the device is catching a problem that could have burned their house down in time. 

This isn't something you screwed up, so don't feel bad about it like it is. Just eliminate the possibilities in order of probability and explain it to the customer as you're doing so. It's not like finding a water leak where we can just trace the flow back to the source and "Aha!" There it is in the shower valve body wall by golly!" 

You've already eliminated everything but the porch lights, their wiring and the switches controlling them. Disconnect the lights, reconnect the switch leg. Problem still exists? Change the switches. Problem still exist? Change the switch leg wiring. Problem solved. I personally still think the issue is with the condensation or the lampholder wires. That's where I would concentrate.


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## mikewillnot (Apr 2, 2013)

chicken steve said:


> Woodsman, does the noodle flow through the 3W to the switch and light, or is it a _'dead end 3W'_ w/o one ?


What's a noodle?


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## backstay (Feb 3, 2011)

mikewillnot said:


> What's a noodle?


Neutral.


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## telsa (May 22, 2015)

It's a neutral that's eating you.


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## mikewillnot (Apr 2, 2013)

Thought it might be a neutral that's been boiled for a while


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## Woodsman (Feb 21, 2011)

Thanks for everyone's good input and advice. I should have mentioned earlier that the 12-2 switch leg runs outside under an eave and, at this point, just hangs out wild and not to connected a j-box as far as I know. The neutral does splice through at the last 3way before the switch leg. My hunch is that there's a pinched hot conductor under a staple or something since the breaker won't trip instantly. In order for me to verify that the cable is or is not damaged, I'll have to rip open the wall and maybe even the eave to check. I am dreading doing this because I don't want to look like an idiot when the cable turns out to be good. Maybe the megger is what I need. This house is a remodel, 5 years in the making, with many electricians who've come and gone and left little info or redlines for me to go off of. 


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## mikewillnot (Apr 2, 2013)

A diagram of the circuit would be helpful


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## chicken steve (Mar 22, 2011)

I vote megger Woodsman.....~CS~


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## b-cap (Oct 7, 2014)

Check to see if the circuit is sharing a neutral.


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## Woodsman (Feb 21, 2011)

I ended up temping in a fresh chunk of nm cable as a switch leg and had the arc fault hold all day. I'll be ripping open the wall to shove a fresh nm cable out to my porch lights. Thanks for your help guys.


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## wendon (Sep 27, 2010)

Woodsman said:


> I ended up temping in a fresh chunk of nm cable as a switch leg and had the arc fault hold all day. I'll be ripping open the wall to shove a fresh nm cable out to my porch lights. Thanks for your help guys.
> 
> 
> Sent from my iPhone using Tapatalk


Better use UF if it's a wet location.


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