Abstract: Breaks in the bare neutral conductor of an underground electric cable can be located by applying an alternating signal across the neutral conductor and a phase conductor at one end of the cable. The neutral and phase conductors are connected together at the other end of the cable. The electrical potential of the alternative signal is measured at a series of spaced apart points on the earth's surface along the cable's path. The potential between points over a cable section with an open in the neutral conductor will be about two orders of magnitude greater than the potential between points above good cable section.