CIRCUIT FAULT DETECTOR

An electrical system fault detector for connection across the source terminals of an electrical system includes circuitry responsive to the relative potentials and current flows between the terminals and a selected point in the electrical system to provide a digital indication of acceptable continuity when current can flow between the selected point and one of the terminals and the potentials thereat are approximately equal. A lack of an indication of acceptable continuity indicates a fault such as an open circuit oran excessive impedance between the selected point and the terminal to which it is connected. An incongruous indication would further indicate a fault such as an incorrect connection or a short circuit. Further circuitry produces and is responsive to an oscillating signal subject to line impedances to distinguish between an open circuit and an excessive impedance.