When Harvey Johnson from C/H was selling me on this AFCI deal he was working on in the early 90s, the scenario they were using for the fault this catches was a lamp cord, behind the bed, buried in dust bunnies gets crushed when they move the bed. It arcs and starts a fire in the fuzz before it trips a breaker. That made sense to me. The 1999 proposal for AFCIs on bedroom receptacles made sense. It got silly when they finally adopted it in 2002 and it picked up the ceiling light and smoke detector.
Everything after that borders on insanity, particularly since the device old Harv described in 1994 still doesn't seem to exist. The goal was always parallel and series arcs. The parallel arc was easy, he was working on the series arc then. They still seem to be having problems with a series arc being detected without nuisance tripping.
