I am hoping someone can give me some insight as to where to look to solve a bizarre problem with a home circuit breaker that is tripping.
Specs: Bulldog "Pushmatic" breaker panel. Yes, it's old, but it's been extremely reliable.
About a week ago, a 20-amp breaker started randomly tripping in the panel. By "randomly" I mean it trips 2 or 3 times a day, with no apparent load on the circuit.
I have traced the circuit. The wire runs from the panel to the basement. There, it goes to a single octagon box, and runs a pullchain light. Out of there, it goes to a receptacle, into which is plugged a gas oven (power for the oven light and control valve for the gas, no real load here). Also from that octagon, another wire goes to an outlet, and some basement overhead lights in other octagon boxes.
And THAT'S IT.
I replaced the breaker. Didn't help. I pulled all the boxes in the basement open, pulled OUT the fixtures to examine the wiring. Nothing is loose, nothing is skinned or shorted. I checked the voltages from hot to neutral, hot to ground, and neutral to ground, and it's all fine (120 v between hot and Neutral or hot-to-gnd, nothing between neutral and ground).
I unplugged the oven, didn't help, so I know it's not that. I pulled the feed wire out of that first octagon box and capped off the wires, so the circuit was running NOTHING. It didn't trip after that.
But if I connect it to anything else, I get this tripping problem.
Oh, one more thing. I also pulled open the service panel, pulled the hot wire off the breaker, and inserted an ammeter. With the oven unplugged, I see zero current draw, which is right. If I turn on one light in the basement, I see about 1.2 amps, which is also about right.
I am beginning to think that it's somehow related to another circuit in the house. But every single thing in the house works (we have gone to every room, turned on every light and appliance, and plugged something into every single outlet in the house. Everything works.
It's almost like it's related to something that comes on and off by itself, like a thermostat, or the furnace hot water circulating pump, but I can't really correlate the tripping to those things either.
Any brilliant ideas?
--- Max