How to Wire a Dimmer Switch

Introduction

Installing a dimmer switch allows you to control the brightness of the lights in a room. Dimmer switches provide a sleek and convenient way to set the perfect lighting mood. Wiring a dimmer switch is a relatively simple project that most homeowners can tackle themselves. In this guide, I will walk you through the complete process of wiring a dimmer switch step-by-step.

Things You'll Need

Before getting started, make sure you have the following materials and tools on hand:

Dimmer switch - Purchase a dimmer switch that is compatible with your lights. Check the wattage rating.
Wire strippers - You'll need these to strip the ends of the wires.
Needle-nose pliers - Helpful for bending and maneuvering the wires.
Voltage tester - Used to check that the power is off before working.
Phillips screwdriver - For opening up the electrical boxes.
Electrical tape - For securing the connections.

Turn Off Power

The first step is to turn off the power to the circuit you'll be working on. Locate the circuit breaker box and turn off the appropriate breaker. Verify power is off by using a voltage tester on the wires in the electrical boxes you'll be working in.

Working with live electrical wires can result in severe shock or injury, so this step is critical.

Remove Old Switch

With the power off, you can now remove the existing light switch:

Unscrew and remove the switch plate cover.
Carefully unscrew the switch from the electrical box. Do not touch the wires yet.
Inspect the wiring and take note of the wires connected to the old switch. Typically there will be two cables, one coming from the electrical box and one going to the lights.
Disconnect the wires from the switch. There may be wire nuts or the wires may be fixed in place on the switch itself.
Remove the old switch from the box.

Connect Dimmer Switch

Now you can wire up your new dimmer switch:

Look at the new dimmer switch wires. There should be two or three of them. One wire will connect to the hot (black) wire running to the lights. The other wire(s) connect to the hot source and neutral (white) wires.
Using needle-nose pliers, bend the wires into a hook shape and wrap them clockwise around the corresponding screw terminal on the dimmer. Tighten the screw over the wire to secure it.
For push-in style connections, insert the wire firmly into the hole in the back of the switch. Listen for a click. Gently tug on the wire to ensure it is fixed in place.
Use wire nuts to join the neutral wires and connect them to the dimmer, if required.
Carefully tuck all the wires into the electrical box. Don't cram them in.

Install Dimmer Switch

To complete the installation:

Mount the dimmer switch in the wall box using the included screws. Make sure it is level and the wires are comfortably positioned.
Put the switch plate cover back on. Tighten the screw snugly over the plate.
Turn the power back on at the circuit breaker box.
Test the dimmer switch by turning lights on and off and adjusting the brightness.

Dimmer Switch Tips

Here are some helpful tips for your dimmer switch installation:

Use a multimeter to determine wire hot, neutral, and ground if unsure.
Install the dimmer switch in the hot wire line, not at the light source.
LED bulbs may require a special LED compatible dimmer. Check bulb specs.
For a 3-way circuit, replace the dimmer switch on the hot wire, not the traveler wires.
If lights flicker, there may be a wiring error or neutral wire issue.
If the dimmer feels warm, immediately turn off power and re-check connections.

With good wiring practices and attention to safety, wiring a dimmer switch is a straightforward DIY electrical project. Take it slow, double check your connections, and you'll have dimmable lighting in no time. Let there be (dimmable) light!