My FIL called me because his pool pump stopped working. When i got there to check it out, I noticed that there was no power getting out to the pump. I then checked the Breaker box to see if the circuit breaker had tripped, but it was ok. After a couple of hours of tracing his wiring and using my multi-meter to try to understand his circuit, I came to the conclusion that there must be an open somewhere between the timer and the pump.
The first thing i though of was an animal eating through the conduit and chewing the wire. When that didn't seem likely, I finally decided to open the Circuit Breaker box to take a look. The first thing I saw was the hot wire (black) going to the Pump was spliced (with a wirenut) inside the breaker box. The load wire coming from the timer was spliced to the black wire that headed out to the pump. This wirenut connection was totally burnt to a crisp. Not only that, but both spliced wires were burnt about 2-3 inches. I suspect that the splice burnt due to a bad connection?????? Probably heated up each time the pump was turned on. I am surprised there wasn't a huge problem as a result. I hate to think about what could have happened.
So, my biggest question, is, what, if anything can protect against this dangerous situation. This circuit is protected in the breaker box with a GFCI breaker, which, when tested, trips as it should. I know that GFCI's measure the difference between the current on the black (line) and white (neutral) and trip if there is a 4-6ma difference ( so it really only protects if the frame of the appliance or ground, is exposed to the hot wire, thus sucking up some of the current before it flows to the neutral wire). I think i can understand why the GFCI would not trip (current going thru the bad splice is the same that returns to the GFCI on the neutral side).
Is there anything that can protect against this type of failure (other than making sure the splice is good)?