How to Wire a Three-Way Switch

Wiring a light that has two switch locations is not a normal act for most people; fortunately for us here today, that isn't going to be necessary, because we are only going to wire one three-way switch that will control such a light.

Learning to wire a three-way switch requires that we pay attention, have a slot head screw driver handy and have a new three-way switch to install.

  1. First you will turn off all power to this light switch, if you already haven't. Then you will remove the cover from the light switch and take a good look at what you have and where everything on the switch is located. What you will see is a switch with only one electrical connection on one side, but with two electrical connections on the other side. This is not your normal light switch, is it?

  2. Now that you've seen what's ahead of you, evenly loosen the switch mounting screws and pull the switch out of the box as you loosen the screws. Doing it this way makes the screws easier to turn to remove. Once the switch is pulled out of it's box you will see a total of 4 screws. The green ground screw is at the back. Now, before you go any farther, make a diagram of this switch, and the connection points, the color of the wires and the color of the screw heads. Do this on a clean sheet of paper. Just to be on the safe side. Each wire will only work properly if it is connected to the new switch in the same exact location as it is on the old switch. Like I said, "This is not your normal light switch."

  3. Once you have your diagram made showing the wiring locations of the different colored wires, and the different color screw heads, you are ready to make the change. Remove the old switch and replace it with the new one, making sure that all wire connections are correct and tight when you get done. If you leave a connection loose, you could end up with a fire inside your wall some day, so make it tight.

  4. Now mount the new three-wire switch and push it into the box, insert the screws and replace the cover. Now, turn on the power.