What Is a Three-Way Wall Switch?

Candace Nelson
Written by Candace Nelson
Updated June 11, 2021
Three way wall switch
Image Source / Image Source via Getty Images

Install a three-way switch and never stumble in the dark again

Get quotes from up to 3 pros!
Enter a zip below and get matched to top-rated pros near you.

If you’re tired of running across the garage in the dark, a three-way switch can be the answer. Three-way switches control one fixture from two different light switches—you might have one at the top and bottom of the stairway or at either end of a long hallway.

How Does a Three-Way Switch Work?

To put it simply, a single light switch (or single-pole switch, as people in-the-know call it) is a switch labeled ON or OFF that controls one light. A three-way switch is used to control one light from two different wall switches. 

These aren’t labeled ON or OFF because, when both switches are facing the same direction, the circuit is complete and the light will be on. When the switches are in opposite positions, the circuit is interrupted and the light goes off. An electrician can easily install different types of switches for you.

What Is Happening Inside the Three-Way Switch?

The inner workings of a single-pole switch are black and white. Literally. The switch contains a black wire and a white wire within the insulated coating. When you flip the light on, the terminals connect. Flipping the switch the other way disconnects the terminals and the light goes off. 

A three-way switch has an extra red wire in that sheath, and the switch has three terminal screws. The hot wire carries the power from the source and is marked with a dark-colored screw. It can connect with either of the other terminals, called travelers. Those two travelers are interchangeable and connect to the other switch.

How to Identify a Three-Way Switch

When reaching for a switch, there are a couple tells that show it’s three-way:

  • The toggle isn’t labeled ON and OFF

  • Unscrew the wall plate and see that the switch has three terminal screws and a ground screw (usually two are light in color, a dark colored screw is the common and the ground screw is green).

Pros and Cons of a Three-Way Switch

If you would really like to turn off your bedroom light without getting out of bed, installing another switch can make your life easier. And as far as home improvement projects go, this one is low-cost. The average cost of installing a light switch is $145, but you should expect to pay more for a three-way switch. 

The only setback: adding a new electrical box and switch plate might require some wall repair because you have to cut into the drywall during installation. 

When to Install a Three-Way Switch

If you're already hiring a local electrician to do other work in your house, adding a three-way switch is an easy project for a pro to tackle then, too. You might also want to install a three-way switch when adding or replacing a light fixture or installing a ceiling fan.

How Much Does It Cost to Install a Three-Way Switch?

Expect to pay about $5 to $15 for the switches and $100 to $200 to have them professionally installed. This is an easy job for an electrician, so if you have other work that needs to be done, bundle it together. You can also find a local electrical handyman to do the work.

What You Need to Install a Three-Way Switch on Your Own

Here’s the thing: working with electricity is dangerous work. One wrong move can mean an instant trip to the ER. It’s always best to call a professional for any electrical work. 

But if you feel comfortable working with electrical components and have a history of doing so, you can install a three-way switch on your own with just a few common tools:

  • Screwdriver

  • Electrical tape

  • Needle-nose pliers

  • Non-contact voltage tester

  • Wire stripper

  • Switch and cover plate

  • Electrical cable

If you’re adding a new switch, factor in time and materials for drywall removal and repair. Expect the task to take several hours or a day if you’re doing it yourself. 

Always remember the first rule of electricity: turn off the circuit where you’re working.

Need professional help with your project?
Get quotes from top-rated pros.