Today, I personally went back to the house with the tripping problem and this is what I found.
I opened the panel and put a clamp meter on the circuit in question. It read .18 amps. I went in the house to the affected rooms and hit one switch, the breaker tripped. I reset it and tried another switch, tripped again. I did this with 6 different switches with the same result. After the 6th one I changed the breaker to a regular one. I could then turn every light on without tripping. After I turned everything on, I had a max reading of 11.62 amps on the meter(15 amp circuit).
Most of the switches on the circuit are Lutron Maestro, however even the standard single pole was tripping the breaker, but its fixture is a florescent.
What is causing the arc fault to trip? Nothing has a ground. Everything works fine with a standard breaker. Every switch caused a the circuit to open, so we can't limited the problem to one set of fixtures or switch. The same circuit was causing periodic tripping of a GFCI, but not constant like the arc fault. ?????????????????????
A ground fault would cause the breaker to trip right away unless there is a ground fault in every light fixture.
AFCI's do not have built in GFCI's but they do have GFP. The definition of a GFCI is a device intended for personal protection that functions to de-energize a circuit or portion thereof within and established period of time when a current to ground exceeds the values established for a class A device. Cutler-Hammer does make a combination AFCI/GFCI breaker.
Re: Arc Fault tripping - Revisited#24686 04/19/0308:44 AM04/19/0308:44 AM
If you try measuring the load on the neutral and hot as I suggested above they should be equal. If not the neutral is probably tied in with a neutral of another circuit as stamcon suggested. Another test you could try would be to connect the hot to a standard breaker but leave the neutral disconnected then check to see if any of the lights or receptacles work. If they do your picking up a neutral from another circuit or the neutral from this circuit is grounded somewhere.
Re: Arc Fault tripping - Revisited#24689 04/20/0305:28 AM04/20/0305:28 AM