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.

Thanks,

David

First off, an electrical conduit run outside will get wet. There is not much you can do about it other than maybe some duct seal at the opening to prevent the cold and warm air mixing.

Also, water is NOT causing the breaker to trip. Especially water on insulated wire.
You do have a short circuit somewhere and you need to find it.

If it shorts when light switch is off, then not likely light switched leg. A qualified person that can work safe with electrical might remove wire from breaker, connect that wire and a ground to Audible Continuity tester. It will beep as long as it is shorted, Then go to recepticles on circuit and light boxes, separate wires and see which direction the short is.
If the insulation is cracked, replace it, not only is it the right thing, it may be the problem.

Loose connections could be the culprit.more than likely the panel is utilizing thermo breakers and if you have a lot of heat building up in enclosure,it could also cause inavertant tripping of breakers.I would tighten all electrical connections and look for damage caused by arcing etc..

m45auto, please check the dates of posts you reply to.