Convert 3 way switch to 4 way


  #1  
Old 10-22-18, 12:17 PM
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Convert 3 way switch to 4 way

Sorry if this has been discussed before, I've looked around and couldn't find anything on the subject to fit what I am needing.

So i currently have a 3 way switch set up controlling 3 lights on my stairs. I have one switch at the bottom of the stairs and the second switch at the end of a hallway on the 2nd floor. I would like to add a switch at the top of the stairs since if have 2 rooms closer to the stairs than the second light switch. Trying to avoid having to walk down to one end of the hallway and then back just to turn lights on.
So my question is, with my current set up, how can I add a switch at the top of the stairs?

I currently have
Power coming to switch 1 at the bottom of the stairs
Travelers going to switch 2 up the stairs and down the hallway
Power going out to lights from switch 2

Ideally I would like to add a 14/3 from switch 2 to the new switch at the top of the stairs. Just a little confused on how all the wiring would need to be since the power going to the lights would be coming from switch 2.

Thanks for any help.
 
  #2  
Old 10-22-18, 06:11 PM
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The 4 way switch has 2 travelers in and 2 travelers out. I see 2 approaches depending on which is easier.
1-Abandon cable from switch 1 to switch 2. Run new 3 wire cable from switch 1 to 4 way switch. Run new 3 wire cable from switch 2 to 4 way switch. The 2 neutrals are wire nutted in the 4-way and switch 2 boxes.
2-Disconnect travelers from switch 1 at switch 2. Run two 2 wire (2 travelers) cables from switch 2 to 4-way switch. Connect travelers from switch 1 to 4 way switch inputs and other cable wires to 4 way switch output. Connect the 4-way switch output travelers to traveler inputs at switch 2. Leave neutral as is.


Mod Note: The existing cable does not need to be removed or abandoned.
 

Last edited by pcboss; 11-02-18 at 03:32 PM. Reason: Mod Note:
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Old 10-22-18, 08:33 PM
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Welcome to the forums.

It would be difficult to replace the three wire down to switch 1 on the first floor. Since you want to add an additional switch on the second floor...... the easiest way to do it is to use a piece of 14-4 w/gr NMb from the new switch up thru the attic and down to switch 2.

In order to be 100% code compliant you'd need to run 2) three wire cables from the new switch to switch 2 so that you had neutral at that location. In my opinion..... since that is a 4 way location.... neutral would be unusable there.
 
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Old 10-24-18, 10:35 AM
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Yea I would like to avoid running any wires to switch 1 (If possible), that would involve cutting sheetrock and I would like to avoid that since its a new house.

PJmax, would the 2nd wire from the new switch to switch 2 be to power the lights? I would assume you cant directly power anything from a 4 way switch?

I also have a few outlets on the same circuit. The power for the outlets is coming from switch 2 box. I am also assuming that since the power for the lights is fed from switch 1, that there would have to be a dedicated wire to switch 2 from switch 1 to power the outlets so they are always hot bypassing switch 2 and the wires for the lights other than neutrals and ground.
 

Last edited by andrew539; 10-24-18 at 11:07 AM. Reason: redo
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Old 10-24-18, 06:33 PM
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The 4 way switch you add will be a direct extension off of an existing three way switch. You cannot power anything from it or from that box.

Basically....... you remove the two traveler wires from the 3 way switch. You send them to the 4 way switch on a cable. The travelers are returned to the 3 way switch on a second cable. You require four conductors to do the job..... travelers to the new switch = two wires and travelers back from the new switch = two wires. A 14-4 cable would be the ideal choice if you can locate a short amount.

As far as the power path.... that could be difficult to decode but it's not really an issue here and doesn't get changed.
 
  #6  
Old 11-02-18, 09:51 AM
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Simple. It makes no difference where the power or the fixture are connected. You are going to replace the three way with the four way and install the three way at the new location.Take the three way out and note which wire is on the common. DO NOT change any of the other wiring in the box.
The four way goes in the box where the three way was and the old three way goes in the new box.
Take the wire that was on the common and connect it to the black wire of your new cable.
Take the two original travellers and connect to one set of screws on the new four way. Take the red and white from the new cable and connect to the other set of screws on the four way.
At the new switch box put the black on the common screw and red and white on the traveller screws.
 
 

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