Abstract: A monitoring circuit to detect an open circuit in the ground conductor of an electrical system. The circuit also senses a high inpedance and leakage current in the ground conductor. Additionally, the circuit protects against reversal of the high and neutral input supply conductors. The circuit includes a delayed latching circuit which prevents reconnection of a device to be protected.BACKGROUND OF THE INVENTIONIn many diverse situations involving the use of electrical equipment it is desired to know that the a.c. lines from the source are properly connected and that the ground line is free of faults. This is particularly true where humans will be in contact with the frames and housings of apparatus containing electrical equipment. At the present time it is very desirable, and in some instances mandatory, that ground monitoring devices be used on mining apparatus, and on electrical or electronic medical apparatus, for example.