A ground monitoring tester for an AC power network (100, 300) of an appliance or system, the AC power network (100, 300) having an AC power source, the tester comprising: a processor, in communication with memory, configured to conduct impedance measurements of the ground of said AC power network (100, 300); and an input / output (I/O) module for providing at least one indication output reporting a status of the ground status based on said impedance measurements of the ground, wherein the ground monitoring tester is permanently connected in said AC power network (100, 300) of said appliance or system, wherein the at least one indication output is configured to interrupt power in response to a ground status associated with a first threshold for impedance, characterized in that each impedance measurement is based on a sequence comprising a measurement of a first voltage across a capacitor connected between the AC power source and the ground and a measurement of a second voltage across the capacitor between the AC power source and the ground when a reference load is connected between the AC power source and the ground, wherein the processor determines the impedance based on the measurements of the first voltage and the second voltage for each sequence, and further characterized in that the processor is configured to conduct the impedance measurements repeatedly and indefinitely at intervals of between a few milliseconds and a few minutes, whether or not there is an indication of a problem in the ground of said AC power network (100, 300); and further characterized in that the at least one indication output is configured to provide a warning in response to a ground status associated with a range or a second threshold for impedance. a processor, in communication with memory, configured to conduct impedance measurements of the ground of said AC power network (100, 300); and an input / output (I/O) module for providing at least one indication output reporting a status of the ground status based on said impedance measurements of the ground, wherein the ground monitoring tester is permanently connected in said AC power network (100, 300) of said appliance or system, wherein the at least one indication output is configured to interrupt power in response to a ground status associated with a first threshold for impedance, characterized in that each impedance measurement is based on a sequence comprising a measurement of a first voltage across a capacitor connected between the AC power source and the ground and a measurement of a second voltage across the capacitor between the AC power source and the ground when a reference load is connected between the AC power source and the ground, wherein the processor determines the impedance based on the measurements of the first voltage and the second voltage for each sequence, and further characterized in that the processor is configured to conduct the impedance measurements repeatedly and indefinitely at intervals of between a few milliseconds and a few minutes, whether or not there is an indication of a problem in the ground of said AC power network (100, 300); and further characterized in that the at least one indication output is configured to provide a warning in response to a ground status associated with a range or a second threshold for impedance.