Hi guys. I gotta butt in because this has been somewhat common. The hot switch is the major clue. Pull it out and inspect the terminals and the connector. I suspect you will find two blackened terminals. Resistance can develop on the switch's internal contacts or between the switch's terminals and the connector terminals. Either one will generate excessive heat that will migrate to the other one.
If you find that, replace the switch, and, most importantly, cut out the two blackened terminals and cut away the melted part of the connector body. Cut those two wires back about four inches. You'll feel that part of the wires will be stiff from being hot. Solder won't adhere to that.
Splice in four inches of new wire of the same gauge. Solder the splices and seal them with heat-shrink tubing. Never use electrical tape because that will unravel into a gooey mess on a hot day. You can use common crimp-on terminals to replace the two you cut off, but solder them too. Relying on just the crimp will usually result in another overheated connection in a few months. Plug those two terminals in one at a time by themselves. You do not have to replace the entire connector body and the other terminals.
Be aware that auto-resetting circuit breaker in the switch that HMAC300 mentioned can develop arced contacts that cause more trouble than they prevent. Any resistance will generate heat when current is flowing through it, and that heat is what makes the breaker trip, but in that case the heat is confined to the circuit breaker. The symptom will be flickering lights or lights that turn off for a few seconds up to a minute, then come back on again when the breaker resets, but usually there is not enough heat to make the entire switch feel hot.
Saturday, June 11th, 2016 AT 8:54 PM