Install a Dimmer Switch

Turn off the power to the circuit you're working on at your home's main electrical panel. Find the right breaker and flip it to the "off" position. If you're not sure which breaker it is, turn off power to the entire house. Turn the light switch on to double-check that the circuit is off.

Safety Alert!

Whenever you are working with electricity, use extreme caution. Turning power off is the most important step and should never be skipped. Not only does it protect you from injury, but it also protects the dimmer switch from potential damage.

After turning the breaker off, tape over it with a piece of electrical tape to ensure that no one will turn it on while you're working.

Unscrew the cover plate with a screwdriver and pop it off. Remove the old switch by unscrewing the screws on the top and bottom of the switch. Carefully pull the switch out of the box. To verify that power has indeed been shut off, touch one probe of a neon circuit tester to one of the terminal screws and the other to the metal outlet box, a white (neutral) wire, or a bare (or green) ground wire. Move the probe to the other switch terminal and repeat.

Safety Alert!

If you are changing a very old switch, wires may be loose or brittle. They may even disconnect, which is another reason to be certain the power is off.

Disconnect the wall wires from the existing light switch. If you have a single-pole switch, there should be three wires: One black, one white and a separate ground wire. Depending on where the connections are made, either loosen the terminal screws or insert a small screwdriver into the rectangular hole adjacent to the wire. If you have a 3-way switch, one of the wires will be connected under a different colored screw or will be plugged into a hole in the rear of the switch labeled "Common." Tag this wire with a piece of electrical tape.

Use a wire cutter to trim off the excess bare wire that extends past the plastic insulation. Do this on every wire. Then use a wire stripper to strip off 3/8" of insulation. This will give you a clean piece of wire for the connection to the dimmer switch.

If you're working with a single-pole circuit, take one wire on the dimmer switch and one wire from the wall box and hold them side-by-side. With needle-nose pliers, twist the exposed part of the wires together. Tighten a wire nut over the wires. Repeat with the other two wires. For a 3-way circuit, connect the dimmer's black wire to the wire you taped in Step 4. When all wires have been connected, bend them in a zigzag pattern so that they will easily fold into the wall box. Push the switch back into place. Tighten the two screws that hold it in position using a screwdriver. Install the new dimmer switch plate over the switch and screw it into place using a screwdriver.

Return power to the circuit and test the dimmer to make sure your installation was correctly done. If the dimmer doesn't work, turn off the breaker and double check your wiring connections.

Congratulations! You're done. Now you've added some flexibility to your home's lighting options.