My new dimmer for LED lighting has four wires: one black, one red, one red/white and a green ground. The old dimmer only has three wires: a single red, single black and green ground. This is also going to be a three way. How do I install?

  • Hello, and welcome to Stack Exchange. I edited your post for clarity; please sure I did it right. Did your dimmer come with installation instructions? And how is this to work with a three-way switch? Nov 3, 2018 at 19:37
  • Can you post a photo of the inside of the box you're installing the dimmer into? Nov 3, 2018 at 20:16
  • what do you mean "going to be" a 3-way? Are you also adding a second switch? Is this on a stairway or other place 3-ways are mandatory? Nov 3, 2018 at 22:37
  • Voting to close. Questions remain unanswered and OP hasn't been back.
    – isherwood
    Oct 4, 2019 at 20:38

1 Answer 1


Assuming the dimmer is similar to the Lutron dimmer in this question:

The new dimmer can be used as a regular switch or a 3-way switch.

For a regular switch, which it sounds like the way your old dimmer was connected:

  • Black - Hot
  • Red - Switched Hot
  • Green - Ground
  • Red/White - Not used - cap with a wire nut

For a 3-way switch:

  • Black - Hot
  • Red - Switched Hot/Traveler 1
  • Red/White - Switched Hot/Traveler 2
  • Green - Ground

The second switch for a 3-way setup should be a regular switch, not another dimmer.

Wiring a 3-way switch can be a bit confusing. Search for other information on that (plenty on DIY StackExchange, or Google it) and then just treat the dimmer as one of the 3-way switches.

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