DIY Network

Installing a Dimmer/Sensor

This DIY Basic will provide tips on how to install a dimmer/sensor.

More in Electrical

Step 1: Watch an Overview Video

Step 2: Gather Your Materials and Tools

Materials and Tools:

wall plate
masking tape

Step 3: Get the Facts

  • Dim and turn off lights in your home to save energy and prolong bulb life.
  • Replacing a single light switch with dimmer potentially can save $30 a year.
  • Dimming incandescent bulb 10 percent saves 10 percent of electricity and extends bulb life by 35 percent; dimming bulb 50 percent saves 40 percent of electricity and extends bulb life 500 percent to 10 years.
  • Wasted lighting can account for a majority of a building's total energy usage.
  • Many building spaces remain unoccupied between 40 percent and 70 percent of the day.
  • Average American household uses 11 percent to 15 percent of energy on lighting.

Step 4: Remove the Existing Switch

Stat by turning off power at circuit breaker or remove fuse.

Remove wallplate and switch mounting screws.

Carefully remove switch from wall without removing wires.

Step 5: Identify the Circuit Type

Single-pole switch controls single location. This switch will have insulated wires connected to two screws of same color plus green ground screw.

Two-location control has two switches controlling one fixture. Both switches will be 3-way with insulated wires connected to three screws plus green ground wire; one wire is connected to screw of different color or labeled ‘Common.’

Tag 'Common' wire on both switches to identify when wiring.

If three switches control fixture, two will be 3-way and one will be 4-way.

A 4-way switch has insulated wire connected to four screws plus green ground wire.

Tag two same-color insulated wires connected to opposite colored screws.

Step 6: Connect the Ground Wire

Disconnect switch wires. If wires are aluminum, stop and call electrician.

Connect green ground wire on dimmer to bare copper or green ground wire in wall-box.

First single-location wire goes on black screw terminal on dimmer, second goes on brass screw; no wire goes on blue screw.

For two-location dimmer, tagged wire goes on black terminal, second wire goes on brass, third on blue.

For companion two-location dimmer, tagged wire goes on black, same color wire goes on blue, remaining wire goes on brass.

For three-location dimmers, install one dimmer and two companion dimmers.

Two tagged wires connect to blue terminal, one to screw and other to push-in terminal; third wire goes on black screw; fourth wire goes on brass screw.

Step 7: Install the Wall Plate

Tuck wires carefully into wall-box.

Mount and align dimmer and companion dimmer(s).

Install wall plate.

Turn power back on.

Before replacing bulb, cut power to dimmer.