4 way switch

Old 05-28-01, 07:04 AM
Visiting Guest
Posts: n/a

I am trying to put a third switch on a light. I know that I need a 4 way switch, but I don't know how to wire it. Thanks for any help that you have.
Old 05-28-01, 07:17 AM
Visiting Guest
Posts: n/a
There is many different ways to wire three and four way switches. It really depends on how your exsisting switches are wired. Is the feed at the light or at a switch do the three wire cables go to the light or are they between switches. You must determine this first before we can answer this.Let us know.
Old 05-28-01, 11:16 AM
Join Date: Sep 2000
Location: United States
Posts: 18,497
Upvotes: 0
Received 1 Upvote on 1 Post
Raca is correct if you want to understand all of your choices. But there is one simple scheme that does not require you to know anything about the feed.

Here's how (for these instructions I'll temporarily ignore the bare grounding wire).

(1) Turn off the breaker.
(2) Choose either one of the two 3-way switches from which you wish to run a new cable to the new switch.
(3) Take off the face plate and remove the screws holding the switch in place. DO NOT DISCONNECT any wires yet.
(4) Label or otherwise make sure you know which three wires are connected to the switch. In particular, make darn sure you know which of the three wires is connected to the "common" screw (often the screw is black in color, and often it is marked "COM" in the plastic on the back of the switch). The other two wires are the "travelers".
(5) Now disconnect the three wires from the switch. DO NOT DISTURB any other wires in the box. Do not discard the switch -- you're going to need it in the new box.
(6) Put a 4-way switch in the box where the 3-way switch was. Connect the two travelers to either of the pairs of screws on the 4-way (the four screws are identified into two pairs, either by screw color and/or by markings on the back of the switch). Leave the wire that was connected to the "common" screw unconnected at this point.
(7) Run a new 14/3 cable from this box to the location of the new box (use 12/3 instead if the current wiring is 12-gauge).
(8) In the existing switch box, connect the "common" wire to the like colored wire in your new cable with a wire nut. Connect the other two wires of your new cable (the travelers) to the remaining pair of screws on the 4-way switch. You are now done with this box.
(9) Install a new box at the other end of your new cable.
(10) You will use the 3-way switch you took out of the other box in this new box. Connect the same color wire as the "common" wire in the other box to the "common" screw of this 3-way switch.
(11) Connect the two traveler wires to the other two screws.

You're done with the basic wiring. Be sure to connect all bare grounding wires to each other and to the green screw on the switch (using pigtails if necessary). If the light is not "off" when all three switches are down, you can simply reverse any one of the traveler pairs in any of the three switches.
Old 05-28-01, 11:35 AM
Join Date: Sep 2000
Location: ottawa canada
Posts: 1,164
Upvotes: 0
Received 0 Upvotes on 0 Posts


These have pictures to discribe the basics of 3 way and 4 way switches. You can have as many 4 way switches as you like as long as a 3-way if at both ends of the switch run.

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: