The present disclosure relates to an impedance-based arc detector for CT scanners and method of use and diagnosis therewith, and more specifically, to a two- or three-way conductive probe detector system and associated signal processing unit to distinguish the location of arc faults on a CT scanner at either the high-voltage cable of an x-ray tube, an anode connected to the x-ray tube, a cathode also connected to the x-ray tube, a high-voltage well, or a power distribution unit of the tube.