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How to Wire a 3 Way Switch

This configuration is the most basic three way switch and is a good starting point to learn how to wire a 3 way switch. Three-way switches are used to control power to a light from two different locations.  You must purchase switches labeled as 3-way switches as regular light switches will not work.  3 way switches can be quickly identified by the 3 screw terminals (in addition to the green/gnd screw terminal).

When wiring a three-way switch, you will need 3-wire cable coming from the power source and then 4-wire cable going between the two switches.  This extra wire between the switches in needed for the "traveler" wires.  Wiring from the second switch to your light fixture or fixtures can be regular 3-wire cable.  Here are the definitions of each wire color:

3-Wire Cable/ROMEX
Black wire = HOT or power
White wire = Neutral
Bare copper = Ground

4-Wire Cable/ROMEX
Black wire = HOT or power
Red wire = HOT or power
White wire = Neutral
Bare copper = Ground

When learning how to wire a 3 way switch you must understand all you are doing is controlling the hot wire going to the light.  The neutral will be passed through each junction box all the way to the light.  The black colored screw or terminal on each 3-way switch is called the common terminal.  The black "hot" wire from the power source goes to the common as does the black "hot" wire that leaves the last switch and goes to the light.  The other two terminals on the 3-way switch are used to connect the "travelers" between the two switches.

Basic 3-way switch diagram       

Basic 3-Way Switch Diagram - (pdf, 53kb)

That about wraps it up.  To learn how to wire more advanced configurations of 3 way switches click the link below to go back to wiring diagrams and see all the other 3-way switch configurations that are possible.

Back to Wiring Diagrams Home

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