Mapping and Indexing Circuits

Mark down circuits on sketch

Somewhere inside the service panel -- usually on the door -- there should be an index that shows what circuit breaker or fuse serves which areas of the house. The index helps you shut off power to the correct circuit before working on it.

Codes require service panels to be indexed, but installers sometimes don't bother to trace down each circuit. If there is no index, make one. To complete the index, work systematically to identify the circuit for every electrical outlet in the house. Be prepared to find some odd combinations. In older homes, a single circuit may travel through several floors. Or you may find an entire circuit serving only a couple of receptacles. Avoid attaching family members' names to the index; they might change rooms. Use more permanent directional designations such as "east bedroom" or "front hall."

Indexing is easier when working with a helper who can turn circuits on and off while you test the lights, receptacles, and appliances.

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Working with a Helper: Communication Methods

If two people are working together, the one stationed at the service panel must let the other know which circuit is off. Once the roamer has finished testing outlets, tell the other person to flip the breaker back on and a new one off.

If the house is small, shouting back and forth can work. In a larger home, use cell phones or walkie-talkies.

If you are working alone, follow this process: Go into every room and flip on all the light switches and lamps. Then shut off all the circuits except one and look for the lights that are on. To tell from a distance whether a receptacle is on or off, plug in a radio and turn it up loud. Once you know the general area covered by a circuit, test all the receptacles systematically.

Step 1

Make a rough sketch of each room in the house, showing the location of all electrical outlets -- lights, receptacles, and hardwired appliances. Don't forget the basement, hallways, attic, garage, and outdoor electrical service.

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Step 2

Flip on all the lights in the house. Assign a circuit number to each fuse or breaker in the service panel. Shut off one breaker or unscrew one fuse.

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Step 3

Test outlets throughout the house. Note lights that have turned off. Open the refrigerator door so you can see whether the light goes on, indicating power to the refrigerator. Turn on appliances and test each outlet in each receptacle.

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Step 4

When you encounter an outlet that has been turned off, mark the circuit number on that room's sketch. After you have tested all outlets, restore power to the circuit you just tested and shut off the next circuit. Work systematically.

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Step 5

Transfer your findings in chart form to a piece of paper that fits the panel door. For clarity, position the circuit numbers near the actual fuses or breakers.

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Using a Circuit Finder

A circuit finder enables you to quickly locate which circuit a receptacle is on. Plug the remote probe into the receptacle. At the service panel point the finder at the breakers until the light glows, identifying the circuit.

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