There are two switches that are side by side. The one I'm replacing with a Smart switch does not have a neutral. The adjacent switch is a 3-way switch and it does have a neutral. Can I share the neutral from the 3-way switch for my Smart Switch? Both circuits are on the same breaker.

The neutral wire is not connected to the switch but is joined in a marrette. Install Smart Switch

  • 3
    Are you calling it neutral because it’s white? It’s connected to one of 3 terminals on a 3-way switch?
    – Tyson
    Commented Jun 13, 2018 at 0:27
  • 2
    3-way switches don't have neutrals. They have a Common and 2 Travelers, any of which might be white, and none of them neutral.
    – brhans
    Commented Jun 13, 2018 at 0:39
  • 2
    Well said guys. OP good chance we can find you a neutral, but we need more info. Any chance of a photo of the old switch wiring and a look into the back of the box? Commented Jun 13, 2018 at 1:02
  • I know it's the neutral because it's not connected to the 3-way switch. The wire comes in to a marrette and back out. I want to run a wire from the marrette as my neutral.
    – user86682
    Commented Jun 13, 2018 at 2:23
  • Can you post a photo of the inside of the box? Or for that matter, do you know if both switches are connected to the same always-hot coming into the box? Commented Jun 13, 2018 at 2:26

2 Answers 2


Looks like your switch is at the end of the line loop. That is why you have neutral and black joining in the switch. This is a case where power goes into light first, and then the switch. Possible case: https://www.buildmyowncabin.com/electrical/wiring-switch-power-into-light.html

enter image description here

For multiple switches, the neutrals are joined together, and that is what you see in the other 3-way using a "marrette" (I had to look this word up) https://www.buildmyowncabin.com/electrical/wiring-diagram-multiple-lights-multiple-switches.html enter image description here

I think you can control by joining with the neutral from other switch (As long as you are sure that it is indeed the neutral). Put the white of current switch into your smart switch live. The black wire going into old switch into smart switch load. Neutral from other switch will go into neutral of smart switch too.

There should have been a black tape on the old switch's white wire. Not sure, it might be just the code requirement in some states (maybe also in Canada). You can add it now anyway.


These white wires aren't the neutrals you are looking for

Neither of the white wires you see in the portion of the box you have visible in your photograph is a neutral -- they're both hot or switched-hot wires that are part of a switch loop, where power and neutral come in at the light and power is continued on to the switch or switches, returning back on the other wire in the cable. This means that there is no neutral anywhere but the light box in this circuit, unfortunately, and you'll have to pull a /3 cable from one of the light boxes to the switch box to add a neutral here, replacing one of the existing /2 cables.

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