My son was using a 1.5HP 120V AC motor to power his loam screening machine. He was using two 50ft # 12 and one 75 ft # 14 extension cords to power this up. After running a couple of hours he stopped the machine for awhile to do other things. When he attempted to get it going again about a half hour later he said it hummed loudly. He quickly unplugged it and noticed that there was a big spark at the plug end and the motor was quite hot. A while later he tried it again and it ran fine. I suggested that he check the ends of the cords and just like I had expected he said that they were all quite warm. We replaced this mess with one continuous length of # 12 with 20 amp ends and all seems fine now so I suspect low voltage or rather excessive voltage drops were his problem. But I have a couple of questions. No one has ever really explained to me why low voltage can damage an AC motor. I had thought that as per ohms law with less voltage there should be less of a current draw and therefore less heat. My other question concerns the initial motor failure. Wat kind of mechanism would cause a motor to shut down as it appeared to by drawing excessive current. It behaved just like a bad, (shorted) motor initially and then resumed working perfectly later on. Thanks. Lenny