Circuit Breaker Tripping
We have an older house with a mixture of wiring from BX to NM installed at various times. We have 200 A service with a nearly full breaker panel, and a partly finished basement so it's not easy to trace wires. Up 'til now, we have not had any electrical problems in the 12 years we've lived in the house.
Today, during an electrical storm, a breaker tripped, and it trips almost immediately or a few seconds after resetting.
The breaker supplies (as nearly as I can tell) two light fixtures in the finished basement ceiling, each with their own switch, and two outlets on the first floor of the house. It trips even with nothing plugged into the outlets and the light switches off. Nothing else is amiss in all of the other circuits.
When it trips, I do hear a popping sound above the basement finished ceiling (not in proximity to the lights or the outlets), and if it doesn't trip immediately, I can faintly detect an arcing smell. Other than taking down the ceiling, is there an easy way to troubleshoot what the likely cause is? This is an older circuit likely to have BX.
The electrical work looks all very professional so I'd be surprised if there were a hidden splice or box above the ceiling, but I suppose they could have put the ceiling over an existing box. I also checked that it does not supply any outside outlets.