Abstract: An apparatus and method for continuously monitoring and detecting an open ground connection which may occur anywhere between the chassis of an electrical appliance and the grounding terminal of a receptacle. The apparatus includes a plug having a grounding blade and a sensing blade which together form an assembly adapted for insertion into the grounding terminal of the receptacle. When inserted into the grounding terminal, the grounding and sensing blades complete a closed current path formed by a sensing conductor connected to the sensing blade and a grounding conductor connected to the grounding blade. The sensing conductor is connected to an inverter and the input of the inverter is also connected through a resistor to the DC power source so as to place the small current on the sensing conductor at the input of the inverter.