I noticed that I could get a minor belt off my 3 x 1.5KW compressor. I attached my meter to a mains supply 'socket earth', and to 'the chassis'. I watched the AC voltage gradually rise... perhaps increasing in speed slightly as the potential difference increased between the chassis and earth... as it approached 100v AC it was rising at a rate of 4v per second. At 100v AC (on the meter) I switched the motors off, and the voltage dissipated immediately. I presumed the voltage would keep rising until a failure occurred. When connected to Neutral (which is connected to a socket earth) - the voltage stabilised at 10v AC. The amps flowing between chassis and earth were around 1.4mA. -------- Clearly, the chassis needs earthing to the Neutral. However, is a capacitor failing, or is it the motors? Can anybody explain what is happening?