How-To Install 3-Way Electrical Switches

In this tutorial we are going to divert from wood working to talk about it’s distant cousin, electrical switches. Why electricity? Well, because your beloved Porter Cable Random Orbital Sander doesn’t run off steam.

Let’s face it, there is a lot of electricity at work in your shop and sometimes your electrical system needs an update…

This is the second in a four part series focused on electrical switches. In any shop there are many applications for various switches. For this reason it is important to know when and how to use them.

In a shop, you have switches that control electrical power to lights and maybe some receptacles. You also have switches that control motors.

Normal power switches are a little easier to figure out. They generally come rated for 15 amps or 20 amps. When you install a switch on a circuit, check the breaker for that circuit in the panel to see it’s amperage rating. Size your switch to match the breaker.

There are three different switches you can get: Single-Pole, Three-Way, or a Four-Way. There’s no such thing as a double-pole or two-way switch. I don’t know why, that’s just the way it is.

This article will show you how-to install electrical three-way switches! Three-Way Switches are a little trickier than single-poles. We’ve all flipped one and I think we’ve all wondered how they work. Nifty little mind puzzle they are! Spoiler alert! Once you’re done reading this tutorial, they won’t be such a mystery. They’ll make a whole lot of sense to be honest with you. So let’s get started.

First of all, what is a switch? A switch is a non-load device, meaning it doesn’t consume power, which opens and closes an electrical circuit. A pair of three-way switches does this from two locations.

So let’s wire them up. I have my power coming in, I have my light and in the middle I have two switches. Electricity travels in a loop. The black wire is the “hot”. That’s your incoming power. The white wire is your neutral and acts as a return path back to the panel. If either of these wires is disconnected or open, the circuit will not work. The switch always and only controls the hot wire. Never connect the neutral wire to a switch.

You have your hot and neutral coming into the box with the switch and you have a black, a white and a now a red leaving your box and running to the other switch, and you have a black and a white leaving that box and running to the light. Between the switch and the light, the black wire is referred to as a “switch-leg”. In some applications, the switch-leg will be colored purple instead of black. Between the two switches, both the black and the red are referred to as travelers and the white is still the neutral.

Now that we know what our wires are, let’s make our connections. Since we’re only controlling the hot with the switch, we’re going to connect the two neutrals together with a wire nut and stick it in the back of the box. We’re also going to attach all of the ground wires including a pigtail from the switch and stick them in the back of the box as well. Always use a pig-tail, never try to terminate two wires on the same screw. We’re going to do this in the second switch box as well.

That leaves us with our hot, our travelers and our switch-leg. Which one goes to which screw? In this case, only the hot and the switch-leg matter. In our first switch where we have the incoming hot, we’re going to attach the hot to the black screw. On older switches, all of the screws may be the same color. If that’s the case, connect the hot to the screw that stands alone at one end. It won’t have a partner screw across from it. Then connect the black and red travelers to the gold screws. It does not matter which screw they each terminate to. When terminating the wires, I recommend bending little hooks on the ends of the wire and wrapping that hook around the screw. This will hold a lot better. Also as a safety precaution, I would wrap the whole thing with electrical tape a couple of times.

Now at the second switch we’re going to repeat the same exact process except this time instead of terminating the incoming hot to the black screw, we’re going to terminate the outgoing switch-leg. And again, the travelers go to either of the gold screws.

That completes this circuit. When you screw in the switches, it won’t matter which way is up because both directions of the toggle could have the light on or off and there are no words on the face of the toggle that read, “On” or “Off”.

Why does this work? Let me explain. Basically, the three-way switches give the power two different routs to take. The switches control which route the power may take or can give no route at all. Let’s take a look at this in a simpler form.

You see here that the power can take the lower route. If I flip a switch, there is no complete path. Then if I flip another switch, the power now takes the upper route. Flip another switch and there is no route. The light is off. I can keep flipping the switches in any order I want and it always either opens or closes the circuit regardless of what position the other switch is in. Pretty cool, right?

Now on to the light. Simply terminate the switch-leg to one screw and the neutral to the other. Easy as can be. And that’s your three-way switched circuit.

Please feel free to leave questions or comments below and please subscribe, like, and share this tutorial and the videos if you find them helpful!

I’ve got three more tutorials you can read and watch. Click on any of the following links (when they become available) to watch me size and install these other three types of switches: Single-Pole, Four-Way, Motor-Rated

And remember! ALWAYS turn off the power before working on an electrical circuit!

 

Tutorial written by Scott Shaeffer of San Juan Carpentry

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• How-To Install Single-Pole Electrical Switches