How to Install a Dimmer Switch

Adjust the ambience and save energy with this project.

In any given room, a single light setting is unlikely to fill all your needs. Replacing an existing toggle switch with a dimmer switch allows you to control the level of light. Several types are available, including push-on and slide dimmers, but most operate the same way. And as a bonus, by dimming the light, you'll be saving energy.

Here's how to install a dimmer:

Materials and Tools:

dimmer switch

medium-size flat-head screwdriver

needle-nose pliers

crimping tool

circuit tester

barrel crimps

wire nuts


  1. Turn off the power at the circuit breaker, and cover the switch with electrical tape so that no one accidentally turns it back on while you're working on the circuit.
  2. Remove the switch cover plate. Remove the screws from the existing switch and pull it out from the wall.
  3. Use the circuit tester to make sure the power is off.
  4. Disconnect the wiring. Straighten the wires coming from the wall.
  5. Twist a wire from the switch and a wire from the wall together, and snug the connection with the needle-nose pliers. Use a barrel crimp to connect the green wire to the bare copper ground wire. For this installation, it doesn't matter which color wires you use to make your connections. Some building codes require that ground wires be connected with barrel crimps.
  6. Cap the connection tightly with a wire nut.
  7. Repeat the process for the other two wires.
  8. Push the wires back into the box, screw the switch into place and replace the cover. Be sure to install sliding dimmer switches upright; otherwise they could operate in reverse. If the original cover plate no longer fits, replace it.
  9. Turn the power back on at the circuit breaker.

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