How To Wire a 3-Way Light Switch

The easiest way for three-way switches is to place the light between the two switches. You have to look closely at the electrical wiring diagram to understand how it is done.

The cable should be 12.2 Romex right up to the first switch, then run 12.3 Romex to the light and then on to the second switch.

The 12.3 Romex has an extra wire called a traveler (usually red), which is necessary for 3-way switches.

At the first switch, the 12.2 Romex from the circuit run enters the bottom of the switch box and the hot (black) cable connects to the bottom right terminal on the switch.

The 12.3 Romex enters through the top of the switch box. The hot traveler (red) wire connects to top left terminal on the switch. The black (hot) wire connects to the top right terminal on the switch.

The 12.3 neutral (white) wire connects directly to the 12.2 neutral wire with wire nuts and the copper ground wires are also connected together with wire nuts.

At the light box, you should have two ends of 12.3 Romex hanging out. One end comes from the first switch the other end comes from the second switch.

First connect the copper ground wires together with a wire nut to get them out of the way, and then connect the two red traveler wires together with a wire nut as well.

Now find the black wire coming from the first box and the white wire coming from the second box and connect them together with wire nuts. Now, this is important, you need to mark each end of the white wire by wrapping it with black electrical tape. This means you have made it a hot wire. This is a code requirement! It is common practice for 3 and 4-way switches.

Now, at the second switch, you will connect the red traveler wire to the top left terminal. The white, wire now labeled as black with tape, connects to the upper right terminal. The black wire will connect to the lower right terminal screw. The copper wire will connect to the box if it's a metal box or the green ground screw on the switch if the box is plastic.

The light box should now have a black wire and a white wire sticking out which is what you will need to connect the light to.

Larry Angell

www.make-my-own-house.com

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Comments on this article:

» left by Rick from Cincinatti, OH (3 years 124 days ago.)

What if you have more than one fixture between the switches and you have to wire them in paralell?
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» left by lee from elgin, sc (3 years 50 days ago.)

12/3 for a light switch??????????
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» left by Anonymous (2 years 188 days ago.)

this is a two way not three way switch
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» left by Steve Larson from Westcliffe, CO (2 years 186 days ago.)

This worked great with only one light fixture but the lights flicker with the same wiring using two fixtures.
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» left by Justin Watrin from North Branch, MN (2 years 78 days ago.)

I would like to say thank you. The person who said that this was a two way not a 3 way doesn’t know what they were talking about. A three way is where you can turn it on in two different places. Don’t ask me why it’s like that but it is. These instructions help me tremendously with my wiring job. I didn’t realize that I had to cross the black and white wire. This is the best help I could of got better than having someone tell or showing me what to do. For the guy wiring more than one light in for the same switches, in sequence, just match the black to black, white to white and if there is a ground, ground to ground from the first light. I didn't have a problem with the lights flickering as one guy said he did. Once again thanks a million.
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» left by Alan Taylor from San Francisco (1 year 17 days ago.)

My current dilemma is if I turn off the light, and that (either one) switch ends up in the same position (up / down) as the other switch the circuit is dead to the other switch (neither up/down turns on the light) until I reverse the position of the original switch. Happens on both ends of this switch/light/switch. I have changed out the switches with new ones, connected the wires in every way possible, and still no joy. The circuit worked fine until I screwed with it trying to install a different style switch my wife HAD to have! Look honey, I put in your new switches, but they don't work right any more, aren't I the stud?!

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