How to Install Three Way Light Dimmer Switches

Installing three-way light dimmer switches can become very complicated and confusing. Only one switch on your three-way circuit can be a dimmer switch and must be installed in the first electrical box on the circuit, while the other switch on the three-way circuit must be a standard three-way switch. While the dimmer switch from the three-way circuit operates the light intensity, the standard three-way switch only turns the light off and on at the intensity as set by the three-way dimmer switch.

Things You'll Need

• Orange wire connectors
• Red wire connectors
• Dimmer switch cover plate
• Phillips or slotted screwdriver
• Three-way switch
• Single gang switch plate

Instructions

1. Turn the power off to the three-way circuit by turning off the breaker at the main electrical panel.

2. Look inside the first three-way switch box and identify the wires. The first cable set consists of a black, white and bare copper wire. The second cable set consists of a black, red, white and bare copper wire.

3. Connect the white wires together inside the three-way switch box by twisting an orange wire connector onto both wires. Push the white set of wires back into the switch box.

4. Wire the three-way dimmer switch. Connect the black wire from the first cable set to the black wire labeled as the common wire from the switch using an orange wire connector. Connect the remaining black wire from the second cable set to the remaining black wire on the dimmer switch using another orange wire connector.

5. Connect the red wire from the second cable set to the red wire on the dimmer using an orange wire connector. Connect both bare copper wires inside the three-way switch box to the green wire from the dimmer by twisting a red wire connector onto the three wires. Push the three-way dimmer switch into the box and attach it at the top and the bottom of the box. Cover the three-way dimmer with the switch cover plate designed to cover your dimmer.

6. Look inside the second three-way switch box and identify the cable set. This set consists of a black, red, bare copper and a white wire wrapped in black electrical tape.

7. Install a standard three-way switch in the second switch box. Wrap the black wire around the screw marked common (COM) on the right side of the switch, wrap the red wire around the screw on the left side of the switch, wrap the white wire wrapped in black electrical tape around the remaining screw on the right side of the switch. Wrap the bare copper wire around the green ground screw and tighten all three screws on the three-way switch.

8. Push the three-way switch into the second switch box on the circuit and attach it at the top and the bottom of the box. Cover the three-way switch with a single gang switch cover plate.

9. Turn the power back on at the main electrical panel that supplies electricity to your three-way circuit.

Tips & Warnings

• Test to verify that the electricity has been disconnected in the area that you are working to avoid electrical shock.

References

• Do-It-Yourself-Help: 3-Way-Switch Wiring Diagrams
• Ask the Builder: 3 Way & 4 Way Switch Wiring Diagram
• The Home Improvement Web: Installing A 3-way Switch With Wiring Diagrams
• EZ DIY Electricity: How to Install a 3 Way Dimmer Switch