Dear Mr. Electrician: How do you find the circuit breaker in an electrical panel?
Answer: I have used a few methods in my career to find a circuit breaker. When I started working in the electrical contracting profession, circuit breaker finders and wire tracers were not readily available. So we improvised. A photo of my homemade circuit breaker finding accessories is at the top of this article.
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TABLE OF CONTENTS:
FIND A CIRCUIT BREAKER WITH GOOD HEARING
Plugging in an electric radio is a simple and inexpensive method for identifying which circuit breaker controls a live circuit.
An electric radio with the sound turned up is a quick easy way to find the circuit breaker to an electrical receptacle outlet. Plug the radio in, turn the volume up, and go to the electrical panel.
Just flip each breaker off slowly one at a time until you no longer hear the radio. Turn the breaker back on and listen to confirm.
If I can get it to stay in place, I sometimes use my Fluke Non-Contact-1AC-A1-II Voltage Tester like the radio to find the circuit breaker. However, the Fluke doesn’t have a volume adjustment.
AMMETER AND FLASHER
A trick I read about in the 1960s was using an ammeter to find the circuit breaker for 120-volt circuits. I tried it myself many times because it is very accurate.
A flasher button was inserted into a rubber pigtail socket and a 100-watt or larger incandescent light bulb was screwed in. Note that the Flasher Buttons were only rated for sixty watts, but that wasn’t always enough to be obvious on the Amprobe if the circuit had other loads.
I put a plug on the end of the pigtail socket. When plugged into an energized electrical outlet, it would blink consistently.

To find the circuit breaker, I would use my analog ammeter and clamp over every wire inside the electrical panel until I found the blinking amperage.

The needle on the Amprobe Model RS-3 Analog Ammeter would fluctuate as the lights blinked on and off. This also works on ceiling lights by connecting a pigtail socket directly to the ceiling electrical box wires to find the circuit breaker as in the image below.


I sometimes used the Winker plug-in blinker pictured above, to create the same blinking light effect as a flasher button.

Two pigtail sockets joined in series and one flasher button was used for 240 volt circuits.
I still have my flasher buttons, but I have not been able to find them anywhere online to purchase except eBay. They may still be found in some old local stores with inventory from the previous century.
HOMEMADE WIRE TRACER
In the 1980s I was working on a very unique house. All stone and brick construction, inside and out. The house was built in the 1930s and the electrical wiring was installed in steel rigid conduit embedded in the stone and brick. Many conduits ran under the floors.
The original cloth wiring needed to be replaced so pulling it out and replacing it with new should be easy. The dried cloth insulation came off inside the conduit when pulling out the old wires. Cleaning out the pipes for the new wire took a lot of time.
As part of the wire replacement process, I surmised that there were hidden junction boxes. I had a friend who was an audio engineer tell me what he does to trace wires in the wall.
He uses an old AM/FM radio and clips a public address speaker transformer to the speaker connections. Sometimes he disconnects the speaker once he gets it going so the sound doesn’t interfere.
I used an old AM radio that I alligator clipped some leads onto the speaker terminals. Some new electric radios and boom boxes have an auxiliary speaker output jack which you can use to plug a pair of wires in with the proper plug attached.

On the secondary side of the output transformer, the common gets connected to the ground like a water pipe. One of the other secondary wires connects to an unenergized electrical wire going into the wall.

A telephone pick-up coil connected to a handheld tape recorder was used to hear the sounds of the radio through the wires. The recorder was set on pause, and an earphone was used to hear the tunes from the wall.
I attached the pickup coil to a piece of 3/4″ PVC conduit. I think I cut a small groove for the cord from the pick coil to pass through on the outside of the conduit. Having the PVC made it easy to swing the pickup coil around the walls listening for the radio sounds and finding the circuit breaker.
This method requires a little tinkering to get the sound signal at a level that is audible in the earphone. I would have to move the ground connection around and sometimes change the connections on the transformer for optimal hearing.
CIRCUIT BREAKER FINDER
Nowadays there are all kinds of circuit breaker finders made by companies and some are reasonably priced. I have used a few and found that they all work well, but it can be a little tricky to find the right circuit breaker.
A transmitter is plugged into a live electrical receptacle outlet and it sends a signal over the wires back to the circuit breaker and wires in the electrical panel.
The handheld receiver picks up the signal and gives off a visual or audible alert.
With the sensitivity turned all the way up, almost all of the circuit breakers will give off a reading. You have to slowly dial down the sensitivity until the tone is heard from only one or two circuit breakers. With tandem breakers, it is difficult to distinguish between the two circuits, so both will probably need to be shut off.

My Ideal circuit finder above has been through a lot. I dropped it a long time ago and it split into two pieces. I taped it back together with electrical tape and it still works.

I wrote another article about some of my other personal tools which you can read here.
Here’s a link to more information about modern methods to find the circuit breaker.
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