Simply plug the Transmitter into a socket and trace for the correct breaker at the electrical box; Risk Free, 100% Satisfaction is Guaranteed. Quality products at an amazing value and provide a 1 year manufacturer warranty; Receiver delivers clear visual and audible indications when the correct breaker has been located; Transmitter Input Voltage is available in 100V -120V at 50~60Hz; Work for either circuit breakers or fuses