If you believe that a dimmer switch may be faulty, test the device to ensure that the problem lies with the dimmer switch and not circuit connections. Replace any faulty dimmers with working ones as soon as possible.

Turn the breaker to the dimmer circuit off at the service panel. The service panel houses all of the breakers to a home's electrical system.

Remove the dimmer cover plate from the wall using the screwdriver. Disconnect the dimmer from the wires located within the outlet box. Loosen wire nuts and remove electrician's tape from the wires.

Attach the continuity tester's alligator clip to one of the dimmer wire leads. Hold the continuity tester's probe to the other dimmer wire lead. If the continuity tester's continuity LED glows, the device is working; otherwise, you have a faulty dimmer switch.