The National Electrical Code may be difficult to grasp in its entirety, but a homeowner with a reasonable understanding of electricity should be able to wire her own house to code by remembering a few simple guidelines. First, make a circuit diagram and check it with a professional before beginning. Next, install a grounded service panel large enough for present and projected use. Finally, use accepted wiring procedures and code-approved circuit elements.
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Make a Circuit Diagram
Plan the electrical system by mapping all lights and outlets in the house, and make projections for the amount of electricity each outlet will have to provide. For example, outlets in the basement may be connected to power tools drawing 15 amps or more while those in a closet will probably have minimal loads. Draw out the circuits that will be connected to each circuit breaker, and size the breaker to accommodate the projected load. Remember to include dedicated 220-volt circuits for appliances like the water heater and dryer. Check the diagram with an electrician, who will be able to identify possible hazards or code violations that you may have overlooked.
Install the Panel
The service panel is the heart of your electrical system, and is the interface between it and the power company. Place it in a convenient, but out-of-the way place, although you may be constrained by existing power lines already dropped into place on your house. A 200-amp breaker is sufficient for most homes, but use a larger one if you need it or are planning extensive renovations in the future.
Secure the panel to the wall, then feed in the power company leads and attach the hot wires (red and black) to the brass buss and the neutral wire (white) to the silver buss. Then ground the panel by connecting the ground buss to a stake driven into the ground with 10-gauge ground wire.
Run the Wires
Run the wires to the points of use throughout the house, either pulling them through holes in the studs, floor and ceiling, or, if the walls are already covered, through the basement or attic and up or down through the walls. Whenever possible, staple the wires to the house framing and, if you pass them through holes, make sure the holes are an inch from either face of a framing member so you don't puncture them with drywall screws. You can use 14-gauge wire for circuits that will be connected to a 15-amp breaker but you must use 12-gauge for a 20-amp breaker. Many builders use 12-gauge wire throughout the house.
Connect Circuit Elements
Install electrical boxes for all circuit elements to the framing and position them so they are flush with the surface of the drywall. then follow the standard color-code to connect them to the house circuitry. The black and red wires connect to brass screws, the white wire connects to a silver screw, and the ground wire, which is bare, connects to a green screw. Be sure to install ground fault interrupting (GFI) outlets in all locations where water is present, like the bathroom, kitchen, laundry room and outside the house.
Wiring the Breakers
Connect each circuit to the service panel by wiring it to a circuit breaker, which is a reusable fuse that trips in the event of a circuit overload. Pass each wire into the panel in turn, then remove the sheathing and expose the ends of the insulated wires with a wire stripper. Connect the white wire to the silver buss, the ground wire to the ground buss, and the black wire to a circuit breaker. If there is a red wire, connect it to a separate breaker. Then snap the breaker into position on the brass buss.