Abstract: A method of detecting ground faults in ungrounded equipment having an electrical supply. The method comprises the steps of:Connecting either side of the supply to a chassis ground terminal of the equipment;Impressing a voltage varying alternately between two predetermined values on the terminal relative to one side of the supply;Detecting and monitoring, with respect to this side of the supply, the resulting potential between this side the chassis ground, said potential varying between predetermined magnitudes in the absence of any ground leak;Monitoring said potential, ground faults in the equipment being detectable by a change in magnitude of said varying potential, establishing ground faults by changes in the magnitude of the varying potential andLocating the faults with respect to the sides of the supply from variations to the upper and lower predetermined values.Preferably the limits to the voltage will be a predetermined value and substantially zero.