Don’t be confused by the 3-way switch! This article and detailed wiring diagram explains how to easily wire a 3-way switch.
The 3-way circuit is a very common system found within most residential installations.
3-ways are used any time that you want two switches to operate one light (or lights). The best example of this would be at either end of a long hallway, or at the top and bottom of a stairwell.
At a glance, 3-way switches look the same as the common single pole switch, but instead of having only two screws on which to make your connections, they have two connections on one side, and one on the other.
One of the three terminals is “identified” (by using a different color) and is usually the bottom screw on the side with two screws. It is referred to as the “common” terminal, and the other two are known as “travelers”. This is because the electrical connection either goes from the common screw, to one or the other travelers, depending on the switch position.
How to Wire a Basic 3-Way Switch:
There are several ways to wire up a 3-way circuit, and it would be very difficult to cover them all.
I will touch on one of the most common and easy to follow methods. Follow the instructions below to wire your basic 3-way switch.
Bring the power supply in to one of the switch boxes (one hot, and one neutral), on a #14/2-wire cable.
Then, run a #14/3-wire to the other switch location.
From the second switch, run a #14/2-wire up to the light box.
In the first box, splice the neutral (white) wire from the power supply to the white wire in the 3-wire cable going to the other switch.
Attach the hot (black) wire to the common screw on the 3-way switch.
The red and the black conductor from the #14/3 cable will be called the “travellers”, and will hook up to the two remaining screws on the switch.
At the other switch location, you will hook the white wire from the #14/3 to the white wire going up to the light.
The “travelers” (black and red) from the #14/3 will connect to the same screws as on the other 3-way switch, and the black wire going to the light will tie on to the “common” screw.
Different 3-Way Wiring Configurations
Different 3-way Wiring configurations are covered in the ‘Wiring Diagrams’ portion of the website (click here to access).