Abstract: Apparatus for detecting and locating a fault in an electric cable or cable installation using a pulse-echo or impulse current technique comprises a low voltage pulse generator for injecting a series of pulses into a cable or cable installation; a digital store and memory for recording a predetermined number of pulses and for digitizing and storing the waveforms obtained under two different conditions of the cable; means for terminating the recording of pulses a predetermined time after a fault condition is detected; and means for retrieving the signals obtained under the two separate conditions, comparing them and thus locating the position of the fault.