Today I opened up a panel and I saw a 12 awg neutral wire was very melted. I expected to see that a multiwire branch circuit had been miss wired but after tracing the wire back to the nm cable I saw that it was just a single wire circuit. The hot leg of this cable looked fine. I was wondering what would cause this to happen to only 1 conductor out of 20? I'll be going back next week to investigate more, after the homeowner takes down some sheetrock to expose some burried boxes! :-O In the meantime I disconnected the circuit from the breaker and I unconnected the neutral. Any Ideas?
