How to Use a Circuit Breaker Finder

electronic circuit finder being used in an electrical panel

Circuit breakers are very convenient and common safety devices used to protect your electrical system from overloads and other hazards. But unless your electrical service panel (circuit breaker box) is very carefully mapped, it can be difficult to identify which breaker controls which outlets, switches, or light fixtures.

When an overload or short circuit "trips" a circuit breaker, it easy to identify, as the lever on the breaker snaps to the "off" position. But when you are doing home repair work and just want to turn off a circuit feeding an electrical outlet or light fixture, finding the correct circuit breaker to turn off is usually a two-person job involving you at the circuit breaker box, an assistant at the outlet, and a good deal of shouting back and forth.

A great little device that simplifies this task is an electronic circuit breaker finder, which easily locates a circuit in a breaker box and makes this all a one-person job. These devices work for either circuit breakers or fuses and are very easy to use.

How a Circuit Breaker Finder Works

An electronic circuit breaker finder includes two parts: a transmitter and a receiver. The transmitter plugs into a household outlet (or light socket, using an adapter; see below) for which you're trying to identify the controlling circuit breaker or fuse.

At the breaker box, you use the electronic receiver that is paired with the transmitter. When the receiver passes over the circuit breaker carrying the electronic signal from the transmitter, the receiver rapidly beeps and flashes. It's as simple as that.

A circuit breaker finder
  1. Install the Receiver Battery

    The receiver on circuit breaker finders is powered by a battery. The model shown here uses a 9-volt battery installed in the handle. The battery compartment is easily accessed by sliding a cover back on the bottom of the receiver.

    To use a circuit breaker finder, first install the receiver battery, then adjust the receiver for maximum sensitivity. With the model shown, you simply rotate the receiver's wheel back until it clicks and the LED lights up.

    A circuit breaker finder receiver on/off switch
  2. Test the Receiver and Transmitter

    The next step is to confirm that the receiver will pick up the transmitter's signal. Plug the receiver into a wall outlet. The outlet power should be on, and the transmitter should light up, indicating power. Place the receiver near the transmitter. The receiver should light up and/or beep to indicate it has picked up the transmitter signal. You can now use the device to locate the matching circuit breaker in your breaker box.

    A circuit breaker finder
  3. Match the Circuit to Its Breaker

    Open to the door to your breaker box. Hold the receiver so the sensor tip is at a right angle and directly on the face of a circuit breaker. Slowly move the receiver up and down over the rows of circuit breakers while continually lowering the receiver’s sensitivity until only one breaker or fuse causes the receiver to beep. (Note: Sometimes an adjacent breaker or fuse may cause a beep due to the routing of the wires in the panel.)

    After you have located the correct breaker or fuse, you can turn off the circuit by switching the breaker to the "off" position. The receiver will stop beeping.

    Return to the outlet where the transmitter is plugged in to check that the transmitter light is off, indicating the circuit is no longer energized. This confirms you have turned off the correct breaker.

    Diagram of a circuit breaker finder in action

Using a Circuit Breaker Finder With a Light Fixture

Because the circuit breaker finder's transmitter must plug into an outlet, you can use an inexpensive adapter, called a keyless socket adapter, to plug the transmitter into a light fixture socket.

To use an adapter, turn off the light fixture at the wall switch, and remove one of the light bulbs on the fixture. Screw the adapter into the light bulb socket. Plug the transmitter into the adapter, and turn on the light switch. The transmitter will function just as if it were plugged into an outlet.

Keyless socket adapaters are sold at hardware stores and home centers and cost about $2.

A diagram with a circuit breaker finder and socket adapter