A dimmer switch is great for taking control over the way a room is lit. It gives you the ability to make subtle changes in light levels—to set the mood in a dining room, lower the levels in a child’s room, or even give you flexibility with outdoor lighting.

In addition to these aesthetic benefits, a dimmer also has a couple of important, practical plusses. First, a dimmer saves energy by allowing you to tailor electricity usage very precisely, eliminating waste. It also extends the life of most light bulbs because it minimizes or eliminates the "filament shock" when you flip on a conventional light switch.

Replacing a conventional light switch with a dimmer switch is a relatively simple task, even if you're only a moderately experienced do-it-yourselfer. Note: If you intend to use fluorescent bulbs in the lighting circuit, you will need a special dimmer that is designed for this purpose.

Just remember the cardinal rule: Always shut off the power to an electrical circuit before working on it. Turn off the circuit breaker at the electric service panel, and then refer to the following for step-by-step procedures.

1) Use a screwdriver to remove the wall plate. Then unscrew the switch mounting screws.
2) Grasp the switch by its flanges and gently pull it straight out of the mounting box. With a neon tester, double check to make sure the circuit wires are not electrically charged. It won't light up unless there is still power in the circuit.
3) Unscrew the wires from the switch terminals. If they are poked into holes in the back of the switch, use a small screwdriver to release them. Straighten the ends of the wires, or, if possible, snip them off and strip the ends again
4) Use lineman's pliers to twist the bare end of the green ground wire together with the bare copper ground wire in the box. Then use a wire nut to further connect the dimmer’s ground wire to the circuit's bare copper or green ground wire.
5) Then connect one of the dimmer’s black wires to each of the two black wires in the box.
6) Make sure the connections are tight, and then carefully push the wires into the box to make room for the dimmer. Position the dimmer, and screw it to the mounting holes in the box.
7) Then replace the faceplate. Turn the power back on at the electrical panel, and then try it out.