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Installing a dimmer switch

January 16, 2013

A dimmer switch is one of life's little conveniences that, once installed, you wonder how you ever got along without! Any standard single-pole wall switch is a good candidate for replacement with a dimmer switch as long as there's ample room in its electrical box and the light it's controlling is of the incandescent persuasion.

Don't try to install a dimmer in an undersized box or one that's already jam-packed with circuit wires, and never use a dimmer to control a fluorescent light. All types of dimmer switches have wire leads instead of screw terminals, so make sure you have the right size wire connectors on hand.

Tools and Materials

Neon circuit tester Screwdrivers Combination tool
Needle-nose pliers Dimmer switch Wire connectors

Step 1. Turn off power to the circuit at the main service panel. Use a neon circuit tester to make sure the power is off. Connect the wire leads of the dimmer switch to the circuit wires using wire connectors.

The switch leads are interchangeable and can be attached to either of the two circuit wires. If your dimmer switch happens to have a third (green) wire, this is a grounding lead; attach it to the grounded metal electrical box or the circuit's bare copper grounding wire.

Step 2. A three-way dimmer has an additional wire lead. This "common" lead is connected to the common circuit wire. On a three-way switch, the common circuit wire is the one attached to the darkest (or copper) screw terminal on the old switch; it also may be labeled with the word COMMON on the switch itself. Only one of the pair of three-way switches may be a dimmer switch; both switches will turn the light fixture on and off, but only one can control its intensity.

Need expert assistance? Visit your local Home Depot store to ask their associates about products or how-to instructions. The Home Depot expert associates are also available to answer your questions online. Visit them here.