a safety interlock system is disclosed for microwave ovens or other high voltage electrical apparatus incorporating sensor means for detecting any malfunction . means are provided for interrupting line input power or actuating a failure indicating device or a combination of both . thermally actuated means , such as bimetallic or meltable elements , as well as circuit breakers , relays and fuses are described . the sensor means are associated with each of the interlocks and do not carry regular equipment - load current until such time as a malfunction of the companion interlock occurs . replacement of the faulty equipment by authorized personnel and manual resetting of the interrupt or indicating means before the oven is energized again reduce the risk of accidental radiation , electrical shock or damage to the apparatus .