Is method and system for detecting a particular AC circuit from among a plurality of AC circuits at a circuit box, a transmitter is plugged into the particular AC circuit to be detected, the transmitter creating a high amplitude high-frequency current pulse. With a receiver, sensing the particular circuit at the circuit box by use of a sensing coil and employing a variable gain stage in conjunction with a threshold comparator and latch to pick off a signal caused by the high amplitude high frequency current pulse. The signal is latched so that a microprocessor can read the signal to activate an indication to a user when the particular AC circuit has been located at the circuit box. The microprocessor can be programmed after it is mounted into the receiver by use of a computer which transfers a program to the microprocessor. In an alternate embodiment of the invention, instead of the latch, the threshold comparator connects to an interrupt input of the microprocessor.