How to Install a Dimmer Switch

Replacing a conventional on-off switch with a dimmer is a quick and simple procedure. Remove the existing cover plate and switch with a screwdriver, and wire the new switch in just the same way as the old one. Make sure you turn the power off to the circuit. Imagine controlling how bright you want the light in your home with just the turn of a dial or the lowering and raising of a lever. Dimmer switches add class to any home and are very easy to install.

Dimmer controls are designed to fit in standard toggle-switch wall boxes. Boxes come in different sizes though. If an existing box is to be used, compare the amount of space in it with the size of the dimmer. For new installations, use a box large enough to handle the dimmer and all of the connections easily.

The most common incandescent-light dimmer switch has a rotary knob that you push to turn on and rotate to control brightness.

Dimmer switches are available in various wattage ratings. The rating applies to the total wattage of all lights controlled by the dimmer. The capacity of the switch must be higher than the total wattage of the lighting to be controlled. Don't overload the switch beyond the wattage limits specified on the housing. A common rating is 600 watts, which would be more than adequate, for example, for control of a dining-room fixture containing six 75-watt bulbs.

Three-way dimmer switches are available for use on lights controlled by two switches. Only one of the switches can be a dimmer, but the light may be turned off or on from either switch. Be sure to purchase a dimmer that is designed for this use. Otherwise, the dimmer will only work when the other switch is in a particular position.

Incandescent dimmer switches must be used only to control incandescent lights, and not to control fluorescent lights. Dimmer control of fluorescent lights is possible to, but installation is more complicated and a special switch is required.

What you will need:
A flat-head screwdriver and a voltage tester
Materials:
Dimmer switch
wire caps

Single pole dimmer switch: This type has two black wires. Connect these to the two black (or black coded) wires in the box, using wire caps.

Three way dimmer switches: This type has three wires. This one has a sliding control lever. Connect the dimmer the same way as the switch that it replaces.

Toggle dimmer switch: Moving the toggle up and down gives all gradations between on and off.

High-low dimmer switch: This type is the least expensive because it has only one intermediate setting.

When replacing the old toggle switch with a dimmer switch, measure the available space inside the wall box before you buy the switch. The housing on the back of the dimmer switch may fill up most of the space in the wall box. Also, allow space for wire and wire caps. If the wall box is nailed to the studs, look for nail heads that stick out, leaving less space for the housing.

Dimmers are also available for table and floor lamps. Check your electrical supply store; some attach to lamp cords; some plug directly into wall receptacles.

Before attempting any work on an electrical circuit, turn the power to that circuit off at the main panel. Don't proceed until you have thoroughly tested the box you will be working on with a voltage tester. Always verify that a wire is not hot before touching it. Dimmer switches should be used only to control the degree of illumination. If appliances or motor-driven tools are connected to a dimmer switch they will be severely damaged.