How to Convert a 2-way to a 3-way Light Switch

A light switch on a ceramic background.
  • 1 hours
  • Beginner
  • 10-15
What You'll Need
Two 3 Way Light Switches
Wire Stripper
14/3 Cable
2 Remodeling Switch Boxes
Wire Nuts

Converting a two-way light switch to a three-way light switch is a great way to solve common problems with light switching. A regular two-way switch allows a user to turn on the lights at one location only, while the three-way light switch allows you to turn the lights on and off at two locations with ease. Here is how the conversion is done.

Step 1 - Determine the Best Wire Route

Determine the location for the second switch before planning the wire route. Afterward, determine the best path for the 14/3 cable. This cable has four conductors instead of three. These four include black and red hot wires, a neutral white wire, and a bare ground wire. The best way to run the cable is to run it from the original switch up towards the attic and down to the new switch location. Another way is to run it up the ceiling, then horizontally towards the location of the new switch.

Step 2 - Prepare the Switch Locations

A woman hits a light switch.

Turn off the power supply from the circuit breaker or the fuse box. Remove the faceplate of the old switch to expose the two-way switch. Unscrew the two-way switch, disconnect the wiring, and pull it out. Remove the old switch box and replace it with one of the remodeling boxes. In order to fit the remodeling box, cut a wider opening using a saw. Create a new opening on the location of the new switch and install the other remodeling switch box.

Step 3 - Install the Wiring

On the original switch location, pull out the wire from the power supply and the new 14/3 cable. Connect the white wires and cover them with a wire nut. Connect the bare wires as well and hook one of them to the ground screw on the switch. It is important to connect the black wire from the power source to the black screw or the “common” screw on the switch. The other two wires (black and red) will connect to any of the two brass screws or “travelers” screws. Tuck the wires inside the box and tighten the screws on the switch and faceplate.

On the second switch, pull out the 14/3 cable and the wire that directly connects to the light. The white wires and the bare wires should be connected in the same manner as that of the first switch. The black wire on the cable that connects to the light should be connected to the black or common screw on the switch. The black and red wires from the 14/3 cable should be connected to any of the brass screws on the switch. Mount the switch to the switch box and install the faceplate. Turn on the power supply and test the switches.