Swapping out switch that's part of a 3-way switch in another room


(Charity Froggenhall) #1

Sorry if I don’t get the terminology right, but I’d like to update my laundry room/mudroom so that the lights come on when I enter the room. (I hate coming home into a dark room!) I thought the easiest thing to do was replace the wall switch. There’s a single switch in the laundry room, and there’s another switch as part of a 3 switch for that same fixture out in the garage. If I replace the single switch in the laundry room, will that do anything weird with the wiring?


(Jody) #2

You need to get a 3 way switch/dimmer kit.


(Charity Froggenhall) #3

Thanks for this! I guess I’m asking do I need to replace the switches on both ends of the circuit (the laundry room AND the garage), or just the laundry room?


(Jody) #4

You need to replace both unless you plan on leaving the secondary leg on all the time. The z-wave three way can be used at either end and the states will get properly updated in the ST app. If you leave a standard switch in the mix, then when that switch is off it kills the power to your z-wave switch.


(Beckwith) #5

You have to replace both but be aware you will need a neutral at each end. It isn’t just a straight replacement. It has been a while since I swapped mine out but I believe you can use one of the extra travelers as a neutral if needed.

There are dozens of threads discussing the effort.


(Chrisb) #6

Depending on how you want to do it, you can just add a micro controller to one switch. That might be more cost effective. However I personally prefer to replace the switches with Z-wave myself. If you do replace, you WILL have to replace both as 3-way Z-wave is a different animal than 3-way normal. Rather than retype a bunch of stuff, I’ll refer you to this thread:

Lots of good info there, including from pretty snazzy drawings from yours truly.