View Full Version : Arc Fault Interrupter

Chris Padilla
06-30-2006, 10:58 AM
I could Google this but I wanted to hear SMC's thoughts on AFIs. I don't know much about them. Are they similar to GFCI's at all? Do they require a ground? Where/why are they used? Are they built into breakers or outlets (GFCI's are both)?

Thanks! :)

Mark Rios
06-30-2006, 11:39 AM
They are (very expensive) breakers. They protect the circuit as opposed to only protecting the receptacle. Most homeowners and electrical supply folks that I've talked to really don't like them.

You know when every once in a great while when you unplug some type of fixture or appliance and there is a little spark (arc)? That's what this new code device is designed to protect us from. When that spark happens, probably before we even see it given the speed of electricity, the breaker trips. I'm told that they are VERY sensitive and that alot of people replace them with standard breakers once they get moved in because of their PIA-ness.

Jim O'Dell
06-30-2006, 11:48 AM
Chris, the arc fault protectors I have seen replace the breakers, and have a separate wire that hooks up, maybe to ground-not sure. I've only seen them at the BORG. Hopefully an electrical person will chime in and give some better insight. Jim.

Jim Becker
06-30-2006, 11:52 AM
I installed one to cover the girls' room before we brought them home permanently...both because it's appropriate and because that wiring is not grounded. (250 year old portion of the house) The install was easy...it's just a breaker replacement, more or less, with an extra wire or so since the neutral also gets "isolated". (You'll need to be able to identify the correct neutral to pull from the buss if it's existing wiring) They protect from such things as frayed conductors on cords, etc...both for fire/sparking and electrocution...any form of "arcing"...hence, the name.

I believe that they may be required by code now for new work for bedrooms, etc.

Mark Rios
06-30-2006, 1:12 PM
I believe that they may be required by code now for new work for bedrooms, etc.

You are correct Jim, here in CA anyway. Code requirement for new construction and remodel.

Sparky Paessler
06-30-2006, 2:35 PM
Arc fault breakers have a DSP in them that looks at the current signature of the circuit and if it detects the signature of an arc shuts down the circuit. Loose wires, bad connections, etc. can cause arcs which cause heat build up which cause fires. Right now they are only required on all bedroom circuits but I would supect that they will be required on all circuits in the future.

Chip Olson
06-30-2006, 3:39 PM
New air conditioners have AFI's built into the plug. Here in Somerville we've had at least two house fires in the past year or so caused by faulty AC's, so this seems like a sensible idea to me.