A dimmer switch controls the power reaching a light fixture, allowing you to dim or brighten the light at the turn of a knob. The switch’s wattage capacity must exceed the total wattage of the lamps in the fixture.
Most dimmer switches are for incandescent fixtures; check the package. An electrician should install a dimmer for a fluorescent fixture.
Caution: Before working on a switch, turn off the power to its circuit. To check that it
is off, turn the existing, working switch on and off; the fixture should not light.
Unscrew the cover-plate screws. If paint holds the plate to the wall, slit the paint with a utility knife. Set aside
the screws and plate. Unscrew the screws holding the switch in the box and disconnect the circuit wires held by the switch’s two terminal screws. Straighten the wire ends.
Connect the wires from the box to the wires on the dimmer switch as shown. Twist the bared ends together and insert them in a wire connector. Twist the connector clockwise, making sure that no bare wire is exposed.
Fit the wires and the switch into the box; screw the switch to the box. Mount the cover plate, push the control knob onto the protruding shaft, and turn on the power.