Home Smart Home Devices Light Switches
Stop walking across a dark room to turn on the light. Install a 3-way switch and control lights from two locations. Flywheel Energy Storage
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 supply. 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.
You may find other configurations in your home. Hire a pro to diagnose anything you’re not sure about, but here’s how to wire a 3-way switch with power coming to the switch first.
Safety note: This project assumes a 15-amp breaker for your lighting circuits. If you see that your breaker is 20 amps, you will need to use 12-2 and 12-3 NM-B cable.
It allows you to control a light or group of lights from two locations.
Anywhere you have two access points for the same room or space, like the top and bottom of stairs, your kitchen or garage, or the back porch.
A single-pole switch controls a light or lights from a single location. One wire comes in from the power source, and one wire goes out to the light(s). A 3-way switch adds two terminals for travelers, which connect two 3-way switches together.
Yes. Just use the common terminal and one of the traveler terminals for the incoming and outgoing power, and leave the other traveler terminal empty. This is a needlessly expensive setup, but there’s nothing wrong with it if you have an extra.
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