How to Install a Leviton Dimmer Switch in a 3-Way Application

Updated at: 20/05/2025

Three-way switches, those allowing light control from two different locations, add convenience and flexibility to your home's electrical system. However, installing a dimmer switch in a three-way setup, especially a popular model like the Leviton dimmer, can seem daunting if you're unfamiliar with the wiring intricacies involved. This seemingly complex task is actually manageable with the right instructions and a methodical approach. Unlike standard single-pole dimmer installations, three-way circuits demand careful attention to traveler wires and the correct placement of neutral wires, making a detailed understanding crucial for a successful and safe installation.

This guide will walk you through the process of installing a Leviton dimmer switch in a three-way application, step by step. We'll cover everything from safely turning off the power and identifying the correct wires to connecting the dimmer and testing your finished installation. By following these clear instructions and safety precautions, you'll be able to upgrade your lighting control with confidence, adding both convenience and style to your home.

Preparation and Safety Guidelines

Tools Needed
  • Flathead screwdriver
  • Phillips head screwdriver
  • Electrician's pliers
  • Wire stripper
  • Electrical tape
  • Handheld voltage tester
Safety Guidelines
  • Always turn off the power at the breaker box before working with any electrical wiring. Failure to do so can result in serious injury or death.
  • Identify and carefully label all wires before disconnecting them. Use a voltage tester to verify the power is off before touching any wires.
  • If you are unsure about any step of the installation process, consult a qualified electrician. Incorrect wiring can damage your electrical system or cause a fire hazard.

Step-by-Step Instructions

  1. Power Off and Device Removal

    • Turn off the power at the circuit breaker.
    • Remove the switch plate and unscrew the existing device from the wall box.
    • Carefully pull the device out to see the wires.
    Carefully pull the device out to see the wires.Carefully pull the device out to see the wires.Carefully pull the device out to see the wires.
    Power Off and Device Removal

  2. Safety Check and Wire Identification

    • Use a voltage tester to ensure no power is present.
    • Identify the common wire (connected to the black screw terminal on the existing switch). Label it with electrical tape.
    Identify the common wire (connected to the black screw terminal on the existing switch). Label it with electrical tape.Identify the common wire (connected to the black screw terminal on the existing switch). Label it with electrical tape.
    Safety Check and Wire Identification

  3. Wiring Removal and Preparation

    • Disconnect all wiring and remove the existing device.
    • Straighten and separate wires; ensure exposed metal ends don't touch.
    • Strip wire ends approximately 5/8 of an inch.
    Strip wire ends approximately 5/8 of an inch.Strip wire ends approximately 5/8 of an inch.Strip wire ends approximately 5/8 of an inch.
    Wiring Removal and Preparation

  4. Wire Connections to Dimmer

    • Place wires under the screw terminal plate and tighten.
    • Connect the ground wire to the green terminal screw.
    • Connect the common wire to the terminal marked 'BK'.
    • Connect traveler wires to terminals marked 'RD' and the remaining terminal.
    Connect traveler wires to terminals marked 'RD' and the remaining terminal.Connect traveler wires to terminals marked 'RD' and the remaining terminal.Connect traveler wires to terminals marked 'RD' and the remaining terminal.Connect traveler wires to terminals marked 'RD' and the remaining terminal.
    Wire Connections to Dimmer

  5. Dimmer Testing

    • Restore power and check if the light turns on to the brightest level.
    • If the light doesn't turn on, refer to the instruction sheet's troubleshooting section. Turn off power.
    If the light doesn't turn on, refer to the instruction sheet's troubleshooting section. Turn off power.If the light doesn't turn on, refer to the instruction sheet's troubleshooting section. Turn off power.
    Dimmer Testing

  6. Final Installation

    • Mount the dimmer in the wall box and attach the wall plate.
    • Turn the power back on.
    Turn the power back on.Turn the power back on.
    Final Installation

Read more: Installing an Outdoor GFCI Receptacle: A Step-by-Step Guide

Tips

  • Wire colors can vary. If unsure, consult an electrician.
  • Always test for power before working with wires.

Common Mistakes to Avoid

1. Incorrect Wire Connections

Reason: Mixing up the traveler wires or connecting them to the wrong terminals on the dimmer switch can result in the lights not working correctly or even damage to the switch.
Solution: Carefully identify and match the traveler wires based on their color coding and the wiring diagram provided with the Leviton dimmer switch.

2. Ignoring Existing Wiring Configuration

Reason: Failing to accurately assess the existing 3-way wiring before starting the installation can lead to incorrect connections and troubleshooting difficulties.
Solution: Thoroughly check and carefully diagram the existing wiring before disconnecting any wires.

3. Neglecting Power Shutoff

Reason: Working on live wires poses a serious risk of electric shock or injury; failure to properly shut off power before starting the installation is extremely dangerous.
Solution: Always turn off the power at the breaker box before working with any electrical wiring.

FAQs

What special tools do I need to install a Leviton dimmer switch in a 3-way application?
Beyond basic screwdrivers, you'll likely need a non-contact voltage tester to ensure power is off and wire strippers for clean connections. A voltage tester is crucial for safety.
My existing 3-way switches are different brands. Can I still use a Leviton dimmer?
While Leviton dimmers are designed for compatibility, mixing brands in a 3-way setup might cause issues. Ideally, both switches should be Leviton for optimal performance. Check the dimmer's compatibility chart before installation.
What if my lights flicker after installing the Leviton dimmer switch?
Flickering often indicates a loose wire connection, incorrect wiring, or an incompatible dimmer with your light fixture's wattage. Double-check all connections, ensuring they are tight and correctly wired. If the problem persists, the dimmer may be incompatible with the load, or there might be a wiring issue within the circuit.