Don Vandervort, Head Homeboy, has written more than 30 DIY home improvement books, been a segment host on HGTV, served as MSN.com's home improvement expert and written countless magazine articles.
Electricity travels in a circle. It moves along a "hot" wire toward a light or receptacle, supplies energy to the device (called a load), and then returns along the "neutral" wire (so-called because under normal conditions it's maintained at zero volts, or what is referred to as ground potential) to the source. This complete path is a circuit. In house wiring, a circuit usually indicates a group of lights or receptacles connected along such a path. Each circuit in your house can be traced from its beginning in the entrance panel or subpanel through various receptacles, fixtures, or appliances and back to the panel.
Inside your electrical panel, you may discover that an electrician or previous homeowner has installed notations or lists that tell which circuit breakers or fuses control particular circuits. If your panel doesn't contain a reference like this, it's a good idea to map your circuits so, when the need arises, you can quickly find the right circuit breakers or fuses to shut them off or reset them. Though the following instructions refer to circuit breakers, the same techniques apply to panels that utilize fuses or other types of disconnect devices.
If the circuit breakers aren't already numbered inside the electric panel, number them. Make a list that you can post on the inside of the door. Numbers should correspond to each circuit breaker. After each number, note which devices the breaker controls. For an even more thorough mapping, you can sketch a floor plan and make notes on it that identify the breaker numbers for each light and receptacle throughout the house. Another helpful tip: mark the back of switch and receptacle covers with the circuit breaker's number. This circuit map is of a typical two-bedroom house. Note that the dashed lines indicate which switch controls which fixture; they do not show wire routes.
Mapping your circuits is something you should do in daylight with a helper. Be aware that all of your home's power will be off at times and, when you're done, you'll have to reset clocks, timers, and the like. A helpful hint: Receptacles are usually on circuits separate from lighting; major appliances such as furnaces, microwaves, washing machines, electric dryers, and electric ovens often have dedicated circuits.
1) At the electrical panel, turn off all the circuit breakers.
2) Identify any large, double (240-volt) circuit breakers first. Flip one on. Determine which major electrical appliance(s) it supplies by turning on each electric appliance (don't forget equipment such as the furnace and the pool pump) until you find the ones that work.
3) Repeat with other large circuit breakers and major appliances.
4) Have your helper plug a small lamp (or electrical device) into a standard room receptacle.
5) Turn breakers on and off until you reach the one that turns on the lamp. Leave that breaker on and have your helper plug the lamp into other nearby receptacles; note all the ones controlled by that breaker.
6) Room lights will also go on during this process. Note the circuit breaker that controls each set of lights.
7) Repeat this process with other receptacles.
8) Continue until you've located and noted all receptacle and lighting circuits.
Complete Home Wiring Electricity provides us with comfort and conveniences that we often take for granted until something goes wrong. Fortunately for the do-it-yourselfer, electrical work is one of the easiest kinds of home improvement and repair.
