[mikehinton]

I disconnected the branch circuit at its junction box, then reset the breaker to "on." It tripped within about 60 seconds. I could hear the noise in the barn (where a couple of the junction boxes are), but didn't see any visible arcing (it was pitch black in there). When I was speculating about the supply lines, maybe I should have said that the 6 (or 8) gauge wires take the power from the 20 amp breaker in the sub panel to three separate outbuildings via underground PVC conduit. If those supply wires became compromised (e.g. if a gopher chewed through the PVC and wire insulation), that would also trip the breaker, wouldn't it? I'm hoping I don't have to dig up 150 feet of conduit to find the problem