Wire tracers work by relying on the target having an electrical charge or signal which is then detected by a receiver. Lots of electrical utilities transmit a signal when the lines are energized and lines often have different signals which helps to differentiate between the different lines. When a line does not have a signal, wire tracers can induce a signal along the line (using a transmitter) in order to locate it. The wire normally has to be metal in order for it to conduct a signal. The transmitter of a wire tracer sends out a signal and the receiver’s job is to detect this signal. If a signal is detected then the user will hear a noise or see a flashing light on the unit.