One of my circuit breakers started tripping last Friday night. It would trip even when I wasn't using the electrical outlets or lights. Since it wasn't an overloading issue, I replaced the circuit breaker but that didn't solve the problem. So, I concluded it has to be a short circuit. I checked several connections and even replaced an outlet and a light switch but the breaker continued to trip. Last night, I checked the light switch controlling an inside light and two outside porch lights. I should mention that I live in Minnesota and it has been very cold lately. When inspecting the light switch box, I noticed a small amount of water (or condensation) inside the electrical conduit that runs to the outside porch. I checked the attic area and found some condensation on the roof above the electrical conduit but no other sources of water (the roof isn't leaking). In addition, the area about the porch appears to be dry.

I'm now convinced that the water on the 80 year old brittle electrical wires inside the conduit is causing a short circuit. I unplugged the electrical wires running to the outdoor lights and it tripped once last night but hadn't tripped when I left for work this morning. I'm not sure what to make of that. Anyway, I'm wondering how I can prevent water/condensation from getting into my electrical conduit. Also, I would like to know if I should attempt to replace all of that wiring with romex if the breaker stops tripping once the conduit dries.