How to Add an Outlet
Before you start any electrical project or repair, it is very important that you shut the power off. Trip the breaker of the circuit you will be working on and check it with a neon tester to make sure the power is off.
When you go to add an outlet, remember that not all of the wiring in your walls will have all the necessary wires for you to tap into to hook up a new outlet. But most outlet receptacles will have the necessary wires, excluding outlets that are switched outlets. The most common power source to run a new wire from is an existing outlet.
Now you will need to correlate the screw colors on the outlet to the appropriate wire colors. The wires and screws need to be color coded for universal use so there are no wiring errors. The chrome color screw will have the neutral wire, or grounded conductor (white orgray), attached to it. The brass color screw will have the hot wire (black or red) attached to it. The green screw of the outlet will have the equipment grounding wire attached to it, which is a bare wire or a green wire. Most home wiring is complete with either No. 14 gauge or No. 12 gauge wiring. Use the same size cable for a continuation of any extended wiring circuit.
To add the new outlet, you will need to run a new cable between the existing outlet and the new outlet. Make sure you are utilizing the same size cable; the size is usually stamped on the wire. In most cases you will run the wire cable to enter the existing outlet's electrical box. Strip away a minimum of 6 inches of wire inside the box and do the same when you get to the new electrical box location. Once you have run the wires to the new electrical box, you will need to connect it to the outlet. The black hot wire needs to be connected to the brass color screw, the neutral or white wire needs to be connected to thechrome screw and the bare wire needs to be grounded to the grounding screw on the electrical box and the grounding screw, or green screw, of the outlet. Once the wires are connected to the outlet you will need to push everything into the electrical box and screw in your outlet and face plate to complete the project.