Hello. I just installed a GE Combination Arc Fault Circuit Interrupter and it keeps tripping, seemingly for no reason as when it trips there isn't much of a load on it. This is the second one of these I have put in with the same problem, as I thought the first one must have been defective but clearly now it was not. Assuming there is an arc fault somewhere along the line, how might I find it?

You are most likely got it wired wrong go on line and ask how to wire it.

AFCI's can be a real pain, as I'm sure you know.

First, no offense, but check to see if the AFCI is wired correctly. The (usually coiled) white wire that is permanently attached to the breaker connects to the neutral bus bar in the electric panel. The white wire that goes out to the circuit is attached to the "white" (or "neutral") terminal _on_ the breaker. That is _very_ important. The hot wire
that goes out to the circuit is attached to "hot" terminal on the breaker. The bare equipment grounding wire that goes out to the circuit is also connected to the neutral bus bar (IF this is the MAIN electric service panel) If it is a sub-panel, the neutral bar should be isolated from the equipment grounding bar.

Second, unplug everything, turn off all lights, and remove any smoke detectors on the circuit, then see if the breaker holds. If it holds, plug things back in one by one until something trips the breaker.

Remember that if there are smoke detectors on the circuit that smokes are usually interconnected (if one goes off, they all go off). So you will have to pull other smokes in other rooms too.

If it doesn't hold, read on.

Determine which outlets and lights, including smoke detectors are on the circuit. The outlet closest to the electric panel is probably the first outlet. Go to the approximate 1/2 way point in the circuit, pull out the receptacle, take note how it is wired, then remove all the wires from the receptacle and separate them so they aren't touching anything, including the bare equipment ground wires. You don't want _any_ wires feeding downstream. This means you will probably have to remake the equipment grounding wires connection with a wire nut when done.

Turn on the breaker and see if it holds. If it doesn't hold, then go 1/2 way upstream and repeat. If it holds, then go 1/2 way downstream. And so on.

Also, remember that the bare equipment grounding wires and the white neutral wires are ONLY bonded together ONCE at the MAIN electric panel. They should never be connected together after they leave the MAIN electric panel, so look for that too.

Good luck.