You can also check fhte insulation on teh cable for any worn areas to see of the electrical cable had a fault to ground via a conductive material. Overheating of an electrical wire is always a current issue. Somewhere the wire is dumping electricity, having electricity dumped through it, or is not properly connected/grounded and the current is flowing through only a fewstrands of thecable causing excess heat. Like Chuck7 said, check for proper fittings, connections, and worn insulation.