Two existing LED cluster circuits (almost new house) - they have dimmable bulbs (4 & 8 respectively) and three switches each. Is there only one way to properly wire these circuits? If not, do I need the original electrician to add dimmers? If there is only one way to properly wire, can I just add an LED (3way) dimmer at one switch location in each circuit? Will the circuits then be operable from any switch, but only be able to change the dimmer setting at the one with the dimmer switch? .... hoping it is that simple.


What you have is two three-way switches with a four-way in the middle. What you need to do here, for each switch set, is

  1. Identify which are your three-ways (one black + 2 brass screws), and which is your four-way (four brass screws). Put the four-way back together, as you're not going to mess with it.
  2. Pick which of the three-way switches you want to replace with a dimmer. It doesn't matter which one you pick
  3. Wire your dimmer up to the three-way, making sure to note which wire was connected to the black screw

Your dimmer will work with the existing switches without any other changes but you can generally only have one dimmer per circuit (unless you buy something specialized)

  • If the dimmer needs neutral, and many LED dimmers do, you will need to place it in the 3-way switch location that has neutral in the cable, if any do. – Harper - Reinstate Monica Jan 21 '19 at 23:55
  • The (unless you buy something specialized) can lead to some nice options. With Lutron's Caseta series smart switchs one dimmer would replace one of the two 3-way switches. Other switch boxes would have all travelers ganged for pass through to the load. Then those other two switch boxes can have Lutron's PICO remote mounted in a wall mount bracket and be paired to the dimmer. This way you can get dimming and on/off control from all three former switch locations. (Other smart switch technologies may offer differing levels of capability however the Caseta dimmer can be operated without a neutral) – Michael Karas Jan 22 '19 at 5:39

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