How to Replace a 3 Way Switch with a 3 Way Dimmer Switch

By Dave Rongey - Summary:

How to Wire 3Way Dimmer Switches: Common 3Way Dimmer Switch Wire Connections and Light Level Adjustments, Wiring Two 3Way Dimmer Switches.

Guide for Wiring a 3 Way Dimmer Switch

Electrical Question: I replaced the switch that we use most often with a dimmer switch. Now the switch that does not have the dimmer has to be on in order for the dimmer switch to work.

  • I just bought a house that has 2 switches that control my living room light.
  • I replaced the switch that we use most often with a dimmer switch.
  • Now the switch that does not have the dimmer has to be on in order for the dimmer switch to work.
  • When the lights are on they make a buzzing noise that they did not make before with the normal switch. Now, both the old switch and the dimmer switch have 3 posts.
  • Looking toward the switch the top right has the black wire, bottom right has white wire, and left side has a red wire (on the dimmer switch).
  • I just took the wires off the old switch and put them on the dimmer switch just the way they were. Did I do something wrong?
  • The light works and dims but both switches have to be On, and now the On position is when the dimmer switch is down. The dimmer switch has a sliding control.


This electrical wiring question came from: Robert, a Homeowner from Gloucester, Virginia.

Dave’s Reply:
Thanks for your electric wiring question Robert.

How to Wire a 3Way Dimmer Switch

Skill Level: Beginner to Intermediate.
Tools Required: Basic Electricians Pouch Hand Tools and Voltage Tester.
Estimated Time: Depends on personal level experience and ability to work with tools.
Precaution: Identify the lighting circuit, turn it OFF and  Tag it with a Note before wiring the new dimmer.

3Way Dimmer Switch Wire Connections

  • Wiring Two 3Way Dimmer Switches

    • This is a relatively easy fix where the wiring at the dimmer switch is out of sequence, which can be caused by having a traveler wire connected to the point position.
    • In this case simply swap the single point wire with one of the two traveler wires at the opposite end of the switch.
      • NOTE: The Point Wire is commonly the Black Wire on a 3way Dimmer Switch, and the Black Screw on a 3Way Switch.
  • Dimmer Switch Wiring Connections

    • The wiring may be corrected by identifying the point wire or the pair used for travelers and correcting the connections, which are shown in the 3 way dimmer switch wiring diagrams available below.
  • Dimmer Switches Can Cause Lamps to Buzz

    • The buzzing that you hear when using the dimmer switch is coming from the filament inside the lamps which is vibrating at the lower control settings of the 3-way dimmer switch.
  • Adjusting the Light Level of the Dimmer Switch

    • Most dimmer switches have a small adjustment which is located on the top area of the switch, close to the mounting bracket.
    • The cover plate will need to be removed to have access to the adjustment screw on the dimmer switch. Using a small screw driver, make the adjustment so the lights are barely on when the dimmer switch is in the lowest setting.
    • This adjustment will allow the dimmer switch to operate to the lowest setting and have full range of the dimmer  switch.

More about Wiring a 3Way Dimmer Switch

Wiring a switch
Wiring a Light Switch – Diagram 1

Wiring a dimmer switch

  • 3 Way Dimmer Switch Wiring Diagram
    • Fully explained 3 way dimmer switch wiring diagram will take the mystery out of wiring a 3-way dimmer switch.

More information about 3 Way Switch Diagram
3 Way Switch Diagram
3 Way Switch Diagram

  • 3 Way Switch Diagram
    • In response to the requests for this information, I have developed a comprehensive,step-by-step guide designed to walk you through the identification and wiring of your 3-way switches.

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FAQs Frequently Asked Questions and Comments

2 Responses to “How to Replace a 3 Way Switch with a 3 Way Dimmer Switch”
  1. Dave Rongey says:

    Hi Max,
    The Lutron Maestro dimmer is a great high quality dimmer switch, however when more than one switch will be installed in the same area or room, you must install the Lutron Maestro compatible switch as well for the other switch locations as well, because the Maestro dimmer is not compatible with a standard 3-way switch, or with other non Lutron brand dimmer switches. The good thing is that the Lutron Maestro dimmers are great for retrofitting any room, and you may add up to 10 companion dimmers as well. So Max, you will need to purchase one more Lutron Maestro switch to replace your other standard switch, and then you will be able to enjoy all the features of the Maestro dimmer switch.
    I hope this helps,

  2. Max Tarakhovsky says:

    I am trying to replace one of the 3-way light switches with a Lutron Dimmer switch (Lutron Maestro 1-1/4-Amp Light Almond Digital Dimmer, Model #: MACL-153MH-LA). I am not sure what I am doing wrong, but unless I turn on the other 3-way light switch, dimmer switch does not work. The other concern, what if this Lutron dimmer switch can only replace 3-way light switch, which gets the AC power line.
    Please help!
    Thank you very much!


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