Three way switch

Wiring Three Way Switch

 

Three-way switches control lights and receptacles from two points: for example, a light in a hallway that can be operated from the first floor and second floor. Or, a light in a garage that can be turned on/off from the garage and the kitchen or pantry, etc.

How to wire a 3-Way switch. Wiring a 3-way switch is a little more tricky than wiring a 2-way switch. First of all we need to go over a little basic terminology on switches.  It should also help in understanding the functions of each type of switch. When wiring a 3-way switch circuit, What were doing is simply controlling the power flow (Switching off/on) to the load (a light, lamp, outlet, ceiling fan etc..) from 2 different locations. a couple examples would be:
At each end of a hallway.
At the top & bottom of a stairway.
Each 3-way switch in these examples are controlling the power source to the same load. When wiring a 3-way switch circuit, we will be using a 3-wire cable known as romex coming from the source (such as the breaker box). Then a 4-wire cable going between the two 3-way switches and then a 3-wire cable going from the switches to the load. The 3-wire cable consist of a black wire, a white wire and a bare copper wire, while the 4-wire cable has an added red wire which is hot as well. See Below…

3-Wire Cable
Black wire = Power or Hot wire
White wire = Neutral
Bare copper = Ground

When wiring a 3-way switch circuit, all we want to do is to control the black wire (hot wire) to turn on and off the load from 2 different locations. The diagram below will give you a better understanding how this circuit is wired.
3-Way Switch Wiring Diagram
3-Way Switch Terminals

Notice that there is a 3-conductor cable coming into the first box, then a 4-conductor cable going from left box to right box, then a 3-conductor cable going from the right box to the load.
Now for wiring, lets assume you’re looking at the switch just like it shows.

The Left Box:
The lower left screw is the common and gets the black wire from the source (3-cond). The upper left screw gets the black wire from the right box (4-cond). The upper right screw gets the red wire from the right box (4-cond). The white wires tie together with a wire nut. The bare copper wires tie together with a wire nut. Be sure to attach a bare copper wire to the green screw on the switch.

The Right Box:
The lower left screw is the common and gets the black wire from the load (3-cond). The upper left screw gets the red wire from the left box (4-cond). The upper right screw gets the black wire from the left box (4-cond). The white wires tie together with a wire nut. The bare copper wires tie together with a wire nut. Be sure to attach a bare copper wire to the green screw on the switch.

 

This entry was posted in Uncategorized. Bookmark the permalink.