Steve:
You said.."If the cable was nicked and seeing a parallel short, it should be arcing as soon as the circuit is energized; plugging something in wouldn't make a difference. I don't think the cable is your problem. AFCIs aren't supposed to trip on series shorts, either, but it wouldn't hurt to double-check the wirenuts and other splices."
I'm under the understanding that a combo AFCI sees series and parallel faults, hence the 'combo' designation. I don't profess to be an AFCI maven as AFCI are 'new' here in NJ as of 10/6/2009, and resi is still slow. I garnered my info from various mfg sites & info, and from a lot of guys here that have AFCI experience.
