Tom R,
The pregnant question still remains...was all well and good UNTIL you turned the key switch on. This is telling you that whatever caused your mini-holocaust was on the other (switched) side of the key.
The smaller the wire gauge, the lower the ampacity rating. A 10 gauge wire would never burn up before a 14 gauge wire in the same circuit unless there was a direct short to ground somewhere in that 10 gauge wire.
Stuart
