AFCI Question

[RBraun]

I am troubleshooting a two wire circuit to a bedroom. It is new wire and drywall has not been applied. The arcfault trips under any load. I removed all wires from the first plug (homerun) to the balance of the circuit and it still trips. I replaced the homerun wire to the first plug and it still trips. I replaced the AFCI with a sister AFCI that works and it still trips. I have checked for any possible interferances to the wiring and have found none.

I am at a loss on this one. Any ideas?

 

[Dennis Alwon]

What are you using to test the circuit? IMO, if the system does not trip with no load then it is possible the problem is what you are using as a testing method

 

[electricalist]

If you disconnected the homerun at its first device there should be no load on it.
If it trips with no load on it then id say its stapled to tight somewhere. .
I generally split a circuit in half to see what direction the problem is.
Id say make sure everything is diconnected at first device.
Sometimes a ground gets bent enough to touch the neutral screw and it wont trip till theres a load on it. If thats true it could be possible with a regular breaker you could show parallel amperage and ground and neutral equally. Dont know that for sure.

 

[mopowr steve]

By any chance did you wire to the afci breaker backwards by mistake? (Where you put the neutral and hot on the screws of the breaker)

 

[Buck Parrish]

If you had a regular breaker tripping, you could turn the light switches off to eliminate beyond that as a problem. Then turn one on at a time until the breaker trips. Bingo you've found it.
Well these combination AFCI's work on the neutral, too. So the switches do not have to be on.
They can be a pain.
I think I've had loose filaments in bulbs cause them to trip. Yes, really, change the bulb and it started working. The home owner said what'd you do? Of course in my professional voice I gave her an answer she nor I could understand, but it sounded good. :happyyes:

 

[James L]

What kind of load are you talking about? Does "any load" include a plug tester?

Is it a portable load you can try on a different circuit, or is it lighting that's wired in (such as can lights)?

I once went to troubleshoot a bedroom afci circuit in a brand new house, customer said it wouldn't stay on at all. Customer wasn't home when I got there. I went in the bedroom and saw a vacuum cleaner sitting there.

Aha, I thought. So I plug the vacuum in and try it. 10 minutes, no trip. So I went to another room, no trip. Hallway, no trip. I literally vacuumed the whole bedroom level.

Then the homeowner walked through the door and I start asking questions. She said it kept tripping when she was trying to plug in her nightlight. I looked at the nightlight, and the photocell was on the front.

Holding it to plug it in covered the photocell, and that was enough arc that it tripped the breaker as it got plugged in. But it did not trip when I made sure not to cover the photocell with my hand as I plugged it in.

I've seen afci breakers trip because a light bulb arced when it got screwed in. I've turned on toggle switches slow enough to trip an afci. Anything that can arc has the potential to trip it.