Three-way switches make it easy to control the same light from multiple rooms. The feature is handy, but it can be tricky to get the wiring just right. Our two-step process explains how to properly replace a three-way switch.

January 26, 2019

If you've ever climbed up the stairs only to realize that you've left the downstairs light on, you understand the beauty of a three-way switch. This handy feature makes it possible to control the same fixture from multiple rooms. Most three-way switches are pretty apparent, but if you're not sure, check the toggle and terminals. If a switch does not have ON and OFF marked on its toggle and has three terminals (not counting the ground), it is a three-way switch. 

Just like any fixture, three-way switches can fall into disrepair over time. If one or both of a pair of three-way switches fail to control the light, replace the faulty switch or switches. If the toggle is wobbly, it's also a good idea to replace the switch.

If you keep track of which wire goes where, replacing a three-way switch is not much more difficult than replacing a single-pole switch. If you forget to tag the wires, however, the proper connections can be difficult to figure out.

For this project, you need to know how to strip wires and join them to terminals. Prep for the job by laying a towel or small drop cloth on the surface below the switch.

Bonus: How to Install a Dimmer Switch

What You Need

  • Screwdriver
  • Electrical tape
  • Wire strippers
  • Wire cutters

Step 1: Shut Off Power and Tag Wires

Shut off power, remove the cover plate, pull out the switch, and test for power by flipping the switch a few times. A three-way switch has a common terminal that's a different color than the two traveler terminals. Tag the wire that connects to the common terminal.

How to Turn Off the Power

Step 2: Restrip and Connect

Cut and restrip wire ends and form them into loops. Connect the ground wire to the new switch. Connect the tagged wire to the common terminal and the other two wires to the traveler terminals. (It doesn't matter which wire goes to which traveler terminal.)

Bonus: How to Replace a Four-Way Switch

If three or more switches control the same fixture, two are three-way switches and the others are four-way switches. A four-way has four terminals (plus a ground). Two wires connect to input terminals and two to output terminals. Before you remove the switch, tag each wire. Without tags, it could take a pro to sort them out.


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