3-pole light switch - neutral wire question


(Thomas Ohm) #1

I want to install Zwave dimmable light switches on a light that has 3 switches. The main electrical gang-box switch box for the light doesn’t have a neutral but the other two electrical switches do. The question is… if I pull a neutral wire from somewhere else for this one switch, will this work? Do all three light switches have to be on the same neutral line? Thought I would ask before I go through the trouble of doing this. Thanks!!!


(Mark) #2

I’m not an electrician.

But I believe you’ll want to pull that neutral wire from the same circuit your lights are already on.

If you tap into another neutral, you could theoretically overload that breaker because now you could have current flowing from this load back to the breaker on that other neutral wire, plus the loads that were already originally on that circuit.


#3

You can’t have normal switches and smart switches on the same circuit. The easiest thing to do would be to buy one z-wave switch and two add-on switches. You then have to wire them according to the add-on switch wiring, usually requiring one wire from the primary switch and a neutral.


(Edward Niedziejko) #4

Several important points:

  1. a white wire in a 3-way switching system is not necessarily a neutral. It’s frequently a “traveller”. If a white wire is connected to a regular 2-way, 3-way or 4-way switch, it’s NEVER a neutral.

  2. You absolutely have to use the same neutral as your power source. They’re a paired set. Usually a switch box will only have one circuit but not always.

  3. Pictures of the wiring are a huge help for determining the wiring method. From what you’ve described though, my suspicion is you’re missing a neutral wire and will need to do some rewiring to make this work.


(Thomas Ohm) #5

Maybe my comment was a little confusing…

I have a light with 3 separate switches. I want to replace all three switches with Z-wave switches (1 master with 2 aux switches). In the back of two of the electrical gang-boxes there is a capped white wire (not attached to the electrical switch) which I assumed was the neutral. But one of the 3 switches in the gang-box for this light does not have that extra white capped wire in the back of the box. I have replaced other 3-pole switches in the past in my home that had this white capped wire in the back of the gang-box which I’ve assume along was the neutral line. Now… I’m stuck with this light because one of the gang-boxes for this light doesn’t have this white-capped line and I’m not sure how to proceed. I do have a close by electrical outlet that does have this capped white line and I thought maybe I could just tap into that line… but now I’m not so sure.


(Edward Niedziejko) #6

This is how you’ll need to rewire your switches. If power comes into the first switch, and the light is connected to that switch as well, and there’s just a 3 wire between switch one and two, and between two and three, you’ll just wire as shown.

The black wire between the master and slave switch boxes can be capped off, it’s not necessary.

Pictures!


(Thomas Ohm) #7

Edward… Yes, that makes sense. THANK YOU! It’s kinda of a bummer though. The gang-box without the traveler should be the where I want the master switch because the master Z-wave dimmable switch I want to use has an LED indicator on it to show the brightness level while the AUX switches don’t. But your diagram reminded me how I did the other 4-pole setup in the past. Thanks again!


#8

It’s difficult to follow without drawings or pictures, but is the neutral in one of your add-on switches box on the same circuit as the load you are trying to control? If so, know that when converting 3 or 4-way switches to smart switches with add-ons, you are going to have an unused wire that you can run neutral back to the master on.