Devices and methods for preventing shock from a high voltage power source. In one embodiment, a device for preventing an electric shock, comprises output terminals for connecting to an external load, a low voltage circuit for carrying a first current (IL) to the output terminals, the low voltage circuit comprising a first coil disposed about a magnetic core, and a high voltage circuit for carrying a second current (IH) to the output terminals, the high voltage circuit comprising a second coil disposed about the magnetic core, and a control relay configured to electrically connect one of the high voltage circuit and the low voltage circuit to the output terminals based at least partly on the first current (IL).