Novice here...

My 2 gang junction box had 2 switches, controlling a fan and its light. I got this fan from HD (Fan) which needed only one hot and a neutral to operate. The remote controls the fan's light. The other switch was wired to 4 new can-lights. The electrician did everything good.

Now, I want to replace the Light switch with a Z-wave dimmer : Dimmer

When I opened the junction box, the existing wiring confused me. The right switch controls lights and left one controls the fan. The new Dimmer needs 4 wires - Line (Hot), Neutral, Ground and Load.

The dimmer switch I have has only 3 Switch Image

Link to Dimmer switch wiring : Dimmer Switch Wiring

Another view enter image description here-

I was able to swap the fan switch with a modern one and it worked fine. However, the Z-wave dimmer I couldn't make it work.

Can someone guide in simple words, how do I wire the dimmer to make it work ?

P.S. The neutral wire hanging down is something I haven't used yet. The dimmer switch said it needed a neutral, so I pulled one from existing lot.

P.S.S. I don't know how the new fan and can lights are wired. I cannot open it either. Sorry!


  • Top center cable is supply or onward power. Bottom right cable is onward power or supply. Don't care which is which. Those will be left alone. Everything you need is already pigtailed, the two yellow wire nuts will not need to be disturbed. The last guy did nice work. Commented Aug 31, 2019 at 23:29
  • @Harper I think you answered it..... but you didn't jump on the backstabs..lol
    – JACK
    Commented Sep 1, 2019 at 0:56

1 Answer 1


I can clearly see in the picture provided your neutral ( the one with a pigtail on it ) is not wired to anything.

That's your "4th wire", if I understood your question correctly. Your old switches didn't need a neutral.. Your new ones will... Use "those" neutrals...

  • That was it. I was just scared to try it out initially. However, I learned something on the way. The neutral wire which I pigtailed and didn't connect to anything caused everything to stop functioning. I learned it the hard way after like 3 hours. The moment I removed it, everything started working as it was earlier. After that it was straightforward. I put it back, and this time put it in the dimmer instead of letting it stay unused. I did swap the line and the load on the dimmer initially accidentally, but that was an easy fix. Thanks for your help.
    – Gary
    Commented Sep 3, 2019 at 0:26

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