Arc Fault Breaker Tripping

[PWR73]

I have ane arc fault SQ D HOM 20A that trips when it is energized. There are a couple of illuminated toggle dimmer switches on that circuit , but otherwise there is no load plugged in. This is an older installation and i tried to retrofit and arc fault into the system. Has anyone had problems with this type of dimmer and an arc fault. What else could it be.

 

[al hildenbrand]

I have ane arc fault SQ D HOM 20A that trips when it is energized. There are a couple of illuminated toggle dimmer switches on that circuit , but otherwise there is no load plugged in. This is an older installation and i tried to retrofit and arc fault into the system. Has anyone had problems with this type of dimmer and an arc fault. What else could it be.

OK. By your description, I understand you to say, you have an existing branch circuit (BC). I assume that you didn't install that BC originally, and that part, if not all, of it is covered by wall surface, so you can't examine it.

Sounds like you've mapped the circuit and know every box that is on it.

1. Remove the load wires from the breaker (leave the line neutral connected) and turn it back on. Tripping indicates bad breaker.
2. Look for continuity between the BC neutral and the equipment ground. If it is there, it needs to be removed.
3. If the BC neutral is cross connected to another circuit's neutral, say in a multi switch box, or if the original BC was a multiwire, that will trip the AFCI.

There's more, but first, is any of this ringing a bell?

 

[kwired]

Look for mentioned neutral to ground faults, also make sure the breaker holds with the load conductors disconnected. Does breaker hold with questioned dimmers removed from the circuit?

 

[Pierre C Belarge]

I have ane arc fault SQ D HOM 20A that trips when it is energized. There are a couple of illuminated toggle dimmer switches on that circuit , but otherwise there is no load plugged in. This is an older installation and i tried to retrofit and arc fault into the system. Has anyone had problems with this type of dimmer and an arc fault. What else could it be.

Some of these switches have the switch lighting bonded to the branch circuit equipment grounding conductor.

When your jurisdiction goes to the 2011 NEC, this will not be permitted anymore.

 

[Pierre C Belarge]

I have ane arc fault SQ D HOM 20A that trips when it is energized. There are a couple of illuminated toggle dimmer switches on that circuit , but otherwise there is no load plugged in. This is an older installation and i tried to retrofit and arc fault into the system. Has anyone had problems with this type of dimmer and an arc fault. What else could it be.

Some of these switches have the switch lighting bonded to the branch circuit equipment grounding conductor.

When your jurisdiction goes to the 2011 NEC, this will not be permitted anymore.

 

[PWR73]

Thanks everyone.

Thanks everyone.

I wont be able to visit that job until later on this week so I'll check it out them.

Thanks for all the help.

 

[jmellc]

Are you putting an AFCI into an existing circuit that you are not adding anything to? If so, that is asking for trouble. That's not required. The multiwire & common neutral already mentioned would mess you up, so would any box with a neu/grnd short or any loose wirenut or loose backstabbed connection.