A system for testing a ground fault detection system in an electric circuit establishes a ground connection between a bus and the ground via an inverter and a load by closing an inverter switch of the inverter and a grounding switch disposed between the load and the ground, determines whether the ground connection is detected, and determines a fault in the ground fault detection system responsive to the first ground connection not being detected by the ground fault detection system. Optionally, a ground fault may be identified by determining three phase voltages provided from each of plural inverters, determining symmetrical components of the three phase voltages for each of the inverters, and identifying a ground fault in one or more of the inverters while powered by the power supply based on the symmetrical components.