**Mapping Electrical Circuits**If you are planning to add any new outlets, lights or appliances to your house, it is helpful to have a map of your electrical circuits. This will help you determine if you can tap into an existing circuit or if you need to run a new circuit from the breaker panel or fuse box. This tutorial will help you map out your home’s electrical system. This map will help you plan for future needs or possibly alert you to an existing circuit overload.

**Overview**Before mapping out your circuits, it helps to understand how electricity works. Begin the project by drawing a floor plan of your house, then turn each circuit off to determine exactly what is on it. Finally, add up the circuit requirements and compare it to the circuit capacity.

**Electricity Basics**Electricity is the flow of electrons through a conductive material. The force with which electrons are moving is measured in volts. The speed that the electrons are moving is measured in amperes or amps. If you multiply volts x amps, you determine the number of watts that the circuit can safely provide. Watts are the amount of power required to run anything electric.

**Calculate Watts**As an example, 14-gauge wire has an amp rating of 15. Standard voltage through most of your house is 120 volts. If you multiply 15 amps x 120 volts, you get 1,800 watts. This one circuit can power eighteen 100-watt light bulbs. Anything beyond this exceeds the capacity of the circuit, which can lead to a blown breaker or possibly greater damage to the electrical system.

**Construct each Circuit**Many appliances require so many watts that they need to have their own circuit. For instance, a large microwave uses about 1,800 watts. An average central air conditioning unit uses 5,000 watts and an electric range uses 12,000 watts. Construct each circuit to handle the watts required by the appliances using it.

**Check Amp Rating**Just as wiring comes in different amp ratings, breakers, fuses, switches and outlets all come in varying amp ratings. When installing a circuit with a specific amp rating, you should make sure that you use wire, a breaker or fuse, switches and outlets that all have an equivalent amp rating.

**Map out the Electrical System**To map out and interpret the electrical system in your house, begin by drawing a floor plan of each floor of your home, then mark the location of each outlet, switch, light fixture and appliance. Turn off the first breaker in your breaker panel or remove the first fuse in your fuse box. Make a note of the amp rating for that breaker for future reference. Using a circuit tester, or a small lamp, test the outlets in your house to determine which outlets are on that circuit. If the tester does not go on, then the outlet is on that circuit.

**Test the Outlets**Mark the breaker number on your drawing next to each outlet that doesn’t have power. Turn light switches on and off to determine if any lights are on the circuit. Test appliances to see if they are receiving power. Mark on the drawing all of the electrical items that are on that circuit. Flip the breaker back on and turn off the next breaker. Continue the testing process until you have determined which breaker or fuse controls every light, outlet and appliance in your house.

**Compare Capacity to Load**To assess the load requirements for each circuit, check the watt requirements of all appliances and lights in your house. Add up the watts required by the lights and appliances on each circuit. Compare the total watts required on each circuit to the watts that the circuit can safely deliver (volts x amps). Many major appliances require a separate circuit to safely provide the watts that are required to run that appliance.

**Add or Split Circuits**Now that you have a map of your electric circuits, you can safely determine which circuit you can tap into, in order to add an extra receptacle. You might also determine that you need to split a single circuit into two circuits to safely handle the load required.