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Installing a 4 way switch

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  • Installing a 4 way switch

    I currently have two 3 ways so i can turn the lights on from two different locations. I'm finishing off my basement and I want to install a 4 way switch so I can turn the lights on/off from 3 separate spots.

    I traced the wire from the fuse panel and its a 14/2 which goes into my smoke detector. From there another 14/2 wire goes to the first 3 way switch. There is a 14/2 coming off the first switch which goes to the first light. All the other lights are branched off the first light. Also in the first switch box is a 14/3 wire which goes to the second 3 way switch. I know the 4 way switch needs to be installed between the first and second 3 ways. Given the way my lights are wired, can i install my 4 way switch in between the 3 ways on the 14/3 wire or do I need to completely rewire my lights to install the 4 way?

  • #2
    Re: Installing a 4 way switch

    Do you have acces to these wires or are they hidden in the walls.Do you have easy acces to the second switch or will you have to fish the wires in the wall?
    You will need to run two seperate runs of 14/2 from the second 3-way switch to the new 4-way switch because you will need four wires.ON a 3-way switch there are three screws that u attach the hot wires to,one of them is marked common.You will want to disconnect the other two wires (called travelers)from the 3-way switch (leave the common wire attached to the 3-way switch). Now you should have the two new 14/2 wires in the 3-way switch box that run to the new 4-way switch.You should now make some connections in the 3way switch box ,take 1 of the new 14/2 wires and connect the black wire to one of the wires you took off of the 3-way switch,and connect the white wire to the other wire you took off the 3-way switch using wire nuts.Now the other 14/2 wire you need to connect the black wire to the 3-way switch,and connect the white wire to the 3-way switch.(these get connected to the switch where you took the old wires off from the 3way switch) In reality all you are doing is running the traveler wires from one 3way through the 4way to the other 3way.
    please do not forget to tie all the bare ground wires together in the 3way switch box.

    hope this helped.



    • #3
      Re: Installing a 4 way switch

      First if the basement is opened up re-feed the switch from the panel. The smoke detector should not be on the same circuit as the lights.

      The first box you described has a feed(2wire from the smoke detector) a load(2 wire going to the lights) and a 3 wire going to the other switch. As it is now the two whites from the 2wires are tied together. The black from the feed ties to the white wire of the 3 wire. The black from the load goes to the black screw on the switch. The black and red from the three wire go to the other screws.

      The other box only has a three wire. The white goes to the black screw, the red and black go to the other 2.

      Assuming that is what you have?

      To put a 4 way in between those 2 boxes you send the 3 wire from the first box to the new box. Then send a 3 from that box to the last box. The whites get tied together. The black and red from each 4wire get tied to the switch.


      • #4
        Re: Installing a 4 way switch

        which switch is can you get a wire fished into, the 2nd box would be best, the first box may not have a large enough cubic inch capacity to add another wire,

        all you need is a new 14-3 from either switch box to the new box, move the 3-way to the new box and put the 4-way in the existing box you connected to

        post which box you can get to and i will tell you how to reconnect the joint for the 4-way, very simple

        dont worry about the circuit connected to smoke detectors, very common for homes to be wired this way


        • #5
          Re: Installing a 4 way switch

          All three presented ways work. Pick your poison.


          • #6
            Re: Installing a 4 way switch

            The wiring is exactly at boytyperanma listed it. I've framed up the walls and sheetrocked most of the walls, but I haven't put in the drop ceiling yet. I have access to the first switch box which I moved into a new wall. The back of that wall is in my workshop and I haven't put up any sheetrock on that side until the wiring is completely. I also have access to the new switch box. The only switch I can't access is at the top of the stairs which is currently where the second 3 way switch is. I do have access to almost all of the 14/3 going to that switch except for the 4ft or so buried into the wall below the switch.

            I was thinking that I could run a new 14/3 line from the first switch box to the new switch box and then run a 14/3 from the new box to the end of the 14/3 from the switch at the top of the stairs. I could tie them together in a junction box or is that not advised.


            • #7
              Re: Installing a 4 way switch

              I would avoid putting any new wires into the first box if you can. It already has a lot of wires in it. It may already be at its conductor fill limit.

              Based on what your saying I'd put a junction box anywhere you'll be able to access on the existing 3wire. From that box run 2 2wires to where you want the new switch. So the junction box would have 2 3wires and 2 2wires. The whites from the 3 wires get tied together. Then tie the remaining wires on each 3wire to each 2 wire black to black, red to white, black to black, red to white. Then you'd have 2 sets of travelers going to the new 4 way switch box. On the switch attach a white and black to each 'side'(read the switch)


              • #8
                Re: Installing a 4 way switch

                does the existing 14-3 wire reach the 1st box the you moved, if it does, replace this box with a 4 x 4 square box with a 1\2" plaster ring,then run 1 14-3 to the new box, put the 4 way in the existing box,

                this is the only wire needed


                • #9
                  Re: Installing a 4 way switch

                  Sounds like there are multiple ways I could do this. The first switch box is a 4x4 about 2.5 inches deep. I have to put another switch in this box for my workshop lights so I am not sure I can add another wire to it for this circuit.

                  So removing the existing 14/3 from the first box that goes to the second switch box and installing a new longer 14/3 from the first box to the new box and then running a 14/3 from the new box to second box is not advised.

                  I'll try running the 14/3 from the first box and the 14/3 from the second box into a junction box and then running two 14/2 to the new 4 way in the new switch box.

                  Thanks for your help


                  • #10
                    Re: Installing a 4 way switch

                    your 2nd box is large enough

                    if you removed the 14-3 from the box, then run new 14-3 from 1st to new box, then 14-3 from new box to 2nd box, put the 3-ways back where they were, 4-way in new box

                    forget about the j-box and the 2 14-2 wires


                    • #11
                      Re: Installing a 4 way switch

                      Cool so I can do it that way. That sounds like the easiest way to go.

                      Thanks for the info everyone.