How to Wire a 4 Way Switch Video
How would you like to be able to control one or more light fixtures from three or more switch locations? It is done with a 4-way switch. This video will show you how to install a four way switch in your home.
First, be sure to turn off the electric service to the circuits you are working on. A 120 volt circuit can kill you. To install a 4 way switch, you need to install it between two 3-way switches. To review, watch the Three Way Switch video first. Tim will wait while you watch.
Now that you have an understanding 3 way switch wiring, do you recall that the white cable, running between the two switches, has a red wire, black wire, white wire and a bare, copper ground wire. These wires will feed right through the 4 way switch. It is just that simple.
A 4 way switch has five screw connections total. There are two on the top, two on the bottom and the green grounding screw. The important thing to remember about the 4 way switch is it must be installed between two 3 way switches. If it is not between the three way switches, it will not work.
The video shows the switch boxes being numbered to help with the description. Box 1 is the first on the 3 way switches; box 2 is the new 4 way switch box being installed and the last 3 way switch box will be number 3.
Cut the white cable near the spot where the 4 way switch box will be located. Mount the switch box and feed both ends of the white cable into box 2 (the 4 way switch box). You should end up with a cable from box 1 going into box 2 and a separate cable from box 3 going into box 2.
Strip the insulation off the two cables and you will be ready to connect the 4 way switch. There will be two sets of red, black, white and copper wires inside box 2. To make the connections:
Wire nut the two white wires together. Twist the two copper wires together, leaving a pigtail to attach to the green ground screw.
That will leave you with 5 wires - two red, two black and the one copper pigtail. Since there are five screw connections on the 4 way switch, all the has to be done is connect these wires to the proper connections.
Where a lot of people make a mistake is if you take the two wires coming from one of the boxes, say box 1, connect one of them to the black screw and on to the brass screw on the same side of the switch, it will not work.
To properly wire the switch, you must connect the wires from box 1 to the two brass screw connectors. It does not matter which color wire goes on which brass screw. Then connect the two wires from box 3 to the two black screws. Again, it does not matter which color wire goes on which black screw. Finally, install the bare copper wire on the green grounding screw.
Restore the power to the circuit and give it a test. Your light fixture is now controlled by three different light switches. As long as the 4 way switch is wired between two 3 ways switches, you will be good to go. Flip the switches and you are done.