If ever a technology encouraged extension cords between rooms, this is it. We've had problems with lights, but usually related to the switch or a bulb that burns out. Plug-in devices that trip an AFCI are appliances with built-in switches or thermostats, like irons, heaters and vacuums.
Since you had a problem in the evening, it makes me wonder about light bulbs. Are any CFL lamps or fluorescent ballasts involved?
Discovered that the home owner had put in CFLs at the front porch lights that were also on PC. Porch is not on AFCI circuit. Removed CFL and disconnected PC. Haven't heard from them for a week. Keeping my eyes crossed.
Thanks All
Mark
