Introduction

Our step-by-step guide with wiring diagrams and complete instructions will help you get a 3-way switch wired in a single day.

A light switch is the simplest of electrical devices. Flip the switch, electricity flows. Flip it again, electricity stops. Lights on, lights off.

That’s great for a small room with one entrance. Other times, we need to turn on the light, walk across the room and turn it off on the way out the other side. Or flip a switch at the bottom of the stairs, and then again at the top. The next person, coming from either direction, must be able to turn the light on again.

That’s where 3-way switches come in.

Unlike single-pole switches, which control lights from one location, 3-ways work in pairs. You must have two of them — and only two. (For more than two locations, add 4-way switches.)

If this sounds confusing, it can be. When I was an electrical apprentice, I could not wrap my head around it. That is, until my foreperson sent me to see why a 3-way switch wasn’t working. That was a day! Now I’m a pro, but a handy DIYer can handle this task, too.

Below, I’ll show you the most common way to wire a 3-way switch. It’s what most electricians use today, because it’s easy and saves money.

Here’s how it works: Power comes into the first switch from the power source. Two wires called “travelers” connect the first switch to the second one. Then power leaves the second switch to go to the light. No matter which switch you flip, the light responds.

Family Handyman

You may find other configurations in your home. Hire a pro to diagnose anything you’re unsure about, but here’s how to wire a 3-way switch with power coming to the switch first.