Replace a switch that controls a light or lights from a single
location with a single-pole dimmer. Replace a three-way switch
with a three-way dimmer.
Step by Step
Turn off power to the circuit, and test the
circuit to be sure it's off. Unscrew the plate covering the switch
and the screws holding the switch in its outlet box. Gently pull
the switch out of its box.
Disconnect the old switch by unscrewing the
wires that had been attached to it. Straighten those wires and,
if necessary, snip the ends and strip the wires afresh.
Connect the dimmer. Most dimmers have two
non-color-coded wire leads instead of terminals. Most don't have
a grounding wire. Pair the dimmer leads with the house wires,
one to black and the other to white (or you may find a white
wire marked black).
If you're replacing a three-way switch with a three-way
dimmer, before you disconnect any wires, note which wire
attaches to each switch terminal. The easiest way to keep
things straight is to attach a piece of masking tape to each
wire and write, on the tape, what that wire was attached
to. Attach those wires to the corresponding traveler terminals
of the new three-way dimmer so they match the wiring of the
old three-way switch. (Don't worry, it's easier to do than
to explain.)
Splice the wires with the twist-on wire connectors supplied
with the dimmer.
Gently fold all wires back into the box by
pushing evenly on the dimmer. Screw the dimmer to the outlet
box, replace the cover plate and then press the dimmer dial
down into the shaft of the dimmer. Turn the power back on,
and you're ready for business.
Buying Advice
A dimmer may hum if it's controlling more bulbs than it's designed to handle.
Be sure to buy a dimmer with a wattage rating greater than the total wattage
of the bulbs it will control. If a bulb hums, replace it with a heavier-filament,
rough-service type.
Safety
Never use an ordinary dimmer to control a receptacle, fluorescent light or
any appliance that has a motor (such as a ceiling fan) or transformer (such
as low-voltage lights). Those devices are designed to run at certain speeds;
when forced to run more slowly on reduced current, they may overheat and
get damaged. You may also destroy your dimmer in the process. Fluorescent
lights require three-wire cables and expensive dimmers.
