How to Install a Dimmer Switch

Replace your standard light switch with a dimmer by turning off the power, removing the old switch, connecting the dimmer wires to the existing circuit wires, and securing everything in place.

1. Kill Power First. Locate the circuit breaker that controls the light switch and flip it to the OFF position. Test the switch to confirm power is off by trying to turn the lights on. Use a non-contact voltage tester on the switch for extra safety.
2. Expose the Old Wires. Unscrew the switch plate cover and set it aside. Remove the two screws holding the switch to the electrical box and carefully pull the switch out. You'll see two or three wires connected to the switch terminals.
3. Verify Zero Voltage. Use your voltage tester to double-check that no power is flowing to any of the wires. This critical safety step prevents electrical shock while you work.
4. Free All Connections. Note which wire connects where before disconnecting anything. Take a photo if helpful. Unscrew the wire nuts or loosen the terminal screws to disconnect all wires from the old switch.
5. Wire the Dimmer. Most dimmers have two black wires that connect to your circuit's hot and switched hot wires using wire nuts. Connect the dimmer's green or bare copper wire to the ground wire in your electrical box. If your circuit has a neutral wire, connect the dimmer's white wire to it.
6. Seat It Flush. Carefully fold the wires into the electrical box and push the dimmer switch in. Secure it with the provided screws, making sure it sits flush against the wall.
7. Power Up and Verify. Attach the new cover plate that comes with your dimmer. Turn the power back on at the breaker and test the dimmer by turning it on, off, and adjusting the brightness level.