Do-It-Yourself Repairs & Basic Home Wiring Projects:
Lights and Switches - Wiring a Basic On/Off Switch to a Light

By Terry Peterman, the Internet Electrician

Step One 

(Refer to Figure 1.)  Connect the ground (bare wire) wire to the device box and cut it off approximately one inch past the ground screw.

Connect the black wire to one screw and the white wire (hot) to the other screw on the switch.

Figure 1.

Note: This is the only time that you want to use a white wire as the "hot" conductor. This is done so you are left with a black and a white wire at the light instead of two whites to hook up to your light.

Step Two

(Refer to Figure 2.)  Usually you will have a 2 conductor #14 cable coming from the light box to the switch box. Conductor is a fancy word for wire and #14 is the size of wire you will use throughout 95% of your house.

Figure 2.

At the light box (octagon box) connect the black wire from the switch to the black wire of the light. Also connect the white wire from the switch to the black conductor coming from the breaker.

Anytime you have a connection between wires it is called a splice. These wire connectors are commonly called marrets.

A splice should be as mechanically strong and as electrically sound as the original conductor

There is another way your switch /light wiring may be laid out. You may have your feeder (wire from breaker) entering the switch box instead of the octagon box. Check out figures 5 and 6. There is no right or wrong way with both of these scenarios; it comes down to what you prefer.

Step Three

(Reference Figure 5.)  Connect the grounds as before. Splice the two white wires under a single marret.

Connect the black wire from the feeder (breaker or incoming power) to one side of the switch.

The black wire from the other cable going to the light is connected to the other side of the switch.

Step Four

(Reference Figure 6.)  Connect the grounds to the octagon box. You can either put one under the ground screw and use a marret to splice them together as shown, or you can put each one under a ground screw.

Connect the white wire from the switch cable to the silver screw of the light fixture.

Connect the black wire from the switch cable to the brass screw of the light fixture.

If another light is going to be on the same switch then simply splice it onto the first light as shown.