I have 12 recessed lights separated into 2 sections, of 6 each currently connected to 2 dimmers. I want to replace the current dimmers with smart dimmers by Leviton. Here are the instructions and diagram from the manufacturer: https://www.homedepot.com/catalog/pdfImages/3e/3e474cd2-a567-4471-a400-3e21fd978b0b.pdf

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Legend: Black - Hot/Load (dimmer 1) Red - Load (dimmer 2) Blue - Neutral Green - Ground

Smart Dimmer 1 works fine, smart dimmer 2 does not work at all, it doesn't power itself on, or switch/dim lights.

What am I doing wrong?

  • Are these on the same circuit, or different circuits? What is the white wire going to Dimmer 2 connected to at the other end? Mar 17, 2018 at 14:37
  • 1
    See the white wire that was capped and you uncapped it? What happens on the other end of that cable? If you don't know, that's your problem. Either the neutral is not tied in, or the red and black don't have the roles you have presumed. Mar 17, 2018 at 20:13
  • @ThreePhaseEel they are on the same circuit, along with a bunch of other outlets and lights
    – Ilya
    Mar 17, 2018 at 22:46
  • @Harper Wire 6 that is capped in old wiring diagram is connected to the neutral screw of the smart dimmer in the new wiring diagram. I don't know what happens on the other end of wire 6.you are probably correct about the roles of red and black.
    – Ilya
    Mar 17, 2018 at 22:52
  • @Ilya -- can you find what's at the other end of wire 6 and report back to us? Mar 18, 2018 at 0:12

2 Answers 2


No, no, no! You have wired 1 cable ground to each device. You need to spiderweb the grounds! All grounds need to go to all other grounds. They should all be joined in a big red, tan or green wire nut.

If the box is metal, you need to tie to the metal box (99% of the time there is a hole threaded for a 10-32 screw, otherwise use a cable clamp or clip). You won't need grounds to the switches because they will ground through the normal mounting screws. (This only works for switches, not receptacles).

If the box is plastic, you need to pigtail a ground to each switch.

Neutrals are not grounds and you do not spiderweb neutrals. Especially here, you need to keep the neutrals separate.

Why won't it work? Because that is not a post-2011 switch loop with neutral. That is a retired 3-way switch run. I don't know what's at the other end, but most likely it can be arranged to be like a post-2011 switch loop with neutral. Find it (most likely at another switch box) and change it.

If you wanted to restore 3-way switch functionality also, that possible with smart switches.


There are two possibilities I can think of:

  1. The smart switch is being smart and is refusing to power on because it detects there is no earth ground connection: You likely lost your earth ground connection to dimmer #2 (and all lights downstream of dimmer #1) by removing the ground pigtail connecting the two cable assemblies attached to dimmer #1. Per the National Electrical Code, dimmer #2 should also be grounded by the same circuit it is connected to and the lights most definitely need to be grounded. I would recommend tying all the ground wires together inside the box and making sure there are connections to both dimmer's ground terminals and the metal box (e.g. pigtails or if there is sufficient wire length, a crimped grounding connector somewhere around all the middle of the length of the ground wires and then allowing the remaining lengths of the 3 wires to individually attach to each element).

  2. The second dimmer is faulty. After you correct the wiring as stated in #1. If dimmer #2 still isn't working, then try wiring it into dimmer #1's place. If it still doesn't power on, then the second dimmer is most probably defective and you should opt to return/replace.

  • @ThreePhaseEel, it is definitely not the 2nd scenario, I swapped Dimmer 1 and 2, and they both work in the Dimmer 1 position. I will give the ground pig tailing idea a go and will report back.
    – Ilya
    Mar 17, 2018 at 22:58
  • 1
    3rd possibility: The blue neutral wire on dimmer2 is actually capped at both ends. Thus no neutral in that box and no possibility for a smart dimmer.
    – Jeffrey
    Sep 6, 2018 at 17:18

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