My son was just troubleshooting an AFCI bedroom circuit, in a remodel that he did not rewire. Every time a floorlamp was plugged in, the AFCI tripped. The homeowner even tried a different lamp, but still would trip.
My son, correctly, it turns out, tried looking at the room's light fixture first, and as soon as he took the canopy off, he saw the problem. The allthread rod was turned up so much inside of the fixture that it had scraped off the insulation.
I'm not sure which wire was in contact, but in this case, the AFCI did indeed work.
Rick Miell
