Follow These 8 Steps for a Simple Dimmer Switch Installation

Skip the middleman and try your hand at dimmer switches

Lauren Wellbank
Written by Lauren Wellbank
Updated July 6, 2022
A beautiful living room with dome lights illuminated
Photo: Tom Merton / KOTO / Adobe Stock
Difficulty

Simple

Saturday skill builder.

Time to complete

1 hour

Cost

$35–$65

Just a short shopping trip (or online order).

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What you'll need:

TOOLS

  • Screwdriver
  • Pliers
  • Wire cutters/wire strippers

SUPPLIES

  • Dimmer switch
  • Connector caps

Experience the full range of light your lighting fixtures have to offer by swapping out your old toggle light switch for a dimmer option. Dimmer switches allow you to control exactly how much (or how little) light you use. You can turn your lights up brighter when you want to sit down with a good book or lower them to the darkest setting when it’s time to snuggle up and watch a movie. 

Most novice DIYers can knock this project out in an afternoon, but if the idea of dealing with electricity leaves you feeling a little queasy, consider calling in a pro. A handyperson charges between $65 and $125 for an average project of this type. 

Preparing to Install a Dimmer Switch

A woman’s hand dimming the lights
Photo: eggeeggjiew / Adobe Stock

This project will likely require a bit of prep work before embarking on a trip to the home improvement store. Consider these four things ahead of your simple electrical DIY: 

  • Your switch: There are a few different options on the market, but most offer either a circular knob that you can turn to find your perfect lighting setting or a sliding bar that will allow you to toggle back and forth. 

  • Bulb compatibility: Ensure the dimmer switch you choose is rated for your light bulbs. For example, LED bulbs will need a specific dimmer to control them. 

  • Number of lights: There are two different dimmer switch options—single-pole (this is standard) and three-way

  • Wattage: Ensure that the dimmer can handle the wattage you want to control with one switch. Add up the wattage of each bulb you want tied to each dimmer switch, and then buy an option rated for that wattage or higher. 

  1. Turn Off the Power

    Close-up of a hand turning on a light switch
    Photo: Iuliia Alekseeva / Adobe Stock

    Before getting started, cut the power that controls the light switch you’ll be swapping out by turning off the breaker that controls the light. Then double-check the switch is off by flipping the light in the room.

  2. Remove the Old Switch Plate

    A plate outlet on a textured wall
    Photo: The Toidi / Adobe Stock

    Using a flat head or Phillips head screwdriver, carefully remove the screws holding the outlet cover in place.

  3. Remove the Old Switch

    Once the switch plate is off, you can access the switch. Gently pull it away from the wall to expose the wires behind the switch. 

  4. Disconnect the Wires

    Disconnect the wires from the screws. Wires are usually screwed into the side of the switch, and the wire is hooked around the screw. 

    • Single-pole Installation: Look for a green grounding wire or a green ground screw 

    • Three-pole Installation: Look for the black “common” wire and the red “traveler” wires

    If the screw for the common wire isn’t already labeled, mark it now, so you know where to reattach the common wire on the dimmer.

  5. Prep the New Wires

    Grab your wire strippers to prep the new wires. Simply clip the bent end of each wire and then strip back about three-quarter-inch of insulation from the end of the wire. 

  6. Attach the Dimmer Switch

    An electrician installing a new dimmer switch
    Photo: Ilja / Adobe Stock

    Once the old switch is disconnected, you can attach the new dimmer switch.

    Single-pole Installation

    Connect the ground wire to the existing green or copper wire in the box. Twist the ends together clockwise and then cover them with the connector nut. Next, connect each remaining dimmer wire to a house wire using pliers. Twist them together and cap them with wire nuts. 

    If unused bare wire is exposed, you’ll need to remove the connector nuts, untwist the wires, and trim them before reconnecting and recapping them again. 

    Three-pole Installation

    Begin with the ground wire and attach it to the existing green or copper wire in the box. You’ll need to twist the ends together clockwise and then cover them with the connector nut. Next, connect the black wire from the new dimmer switch to the common wire and remove any electrical tape. 

    There should be two remaining dimmer wires, known as traveler wires. Reconnect those to the remaining housing wires. 

  7. Mount the Dimmer

    Ensure all wires are tucked safely inside the box before securing the dimmer switch with the provided screws. Then, reattach the switch plate. Double-check that you’ve attached all parts of the dimmer switch correctly before returning to the circuit box to turn the power back on.

  8. Test the Lightswitch

    Return to the dimmer after the power is back on to test your work. To test, simply toggle the switch to confirm the dimmer functions across the entire lighting spectrum. (Optional: Proclaim loudly, “let there be light!” while flipping the switch.) 

    If the dimmer switch doesn’t work, troubleshoot by returning the circuit to the off position, removing the cover, and checking that all wires are attached correctly. 

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