How to Replace a Light Switch with a Dimmer Switch

Step 1. Check to make sure the light turns on and off from the switch you want to replace. Is there more than one switch that controls this light fixture. If you have two switches that controls this light fixture, this is called a “Three-Way” circuit and requires a “3 way” dimmer switch at one location. NOTE: You only need one three way dimmer and one, one “3way” on/off switch for this circuit. You do not need (2) dimmer switches.

Step 2. Once you have purchased the correct dimmer switch for the light fixture circuit, you need to shut off the power at the main breaker box for this circuit. If the circuit is not indentified in the electrical panel, you will need to determine which circuit the light fixture is on. SEE: How to determine which breaker controls which circuit.

Step 3. Now that you have determined which breaker controlled the circuit you want to work on and have turned it off, close the panel and put a large note on the front of the panel indicating that you are working on the wiring and “Do Not Open” this panel.

Step 4. Back at the light switch you want to replace – turn the switch on and off just the make sure there is no power to the switch. Remove the cover plate to the switch with a small straight blade screw driver and set it aside. Remove the top and bottom screws holding the switch to the electrical box. Carefully pull the switch out of the electrical box – Do Not Touch the wiring, sides of the switch with your hands and Do Not Touch The Switch to the Electrical Box. With the switch out and hanging by the electrical wiring check with an electrical circuit tester to verify the circuit is dead. SEE: Basic use of a multimeter or circuit tester.

Step 5. The switch is hanging by the electrical wires and you have verified the circuit is dead. Now inspect the switch, a standard on/off switch will have (3) three wires connected to it: A green or bare copper wire, this is the circuit “ground” and should be connected to the end of the switch. A white wire connected at the side of the switch this wire is the circuit “neutral”. And a black (This could be red or even a different color) wire, this is the circuit “hot” wire and is connected to the second screw on the switch. This is the standard wiring, although the wire colors may not follow what was mentioned above so don’t let this sway you, unless this is a “three way” switch - then its time to call in a professional.

Step 6. Remove the three wires from the switch and set it aside. Look at the new dimmer switch, you will see three wires attached to it. Attach the switch wires to the house wiring as follows: Green to Green, White to White and Black to Black. Secure the wires together with the provided wire nuts and twist till tight. If the dimmer switch has 1-green and 2-black wire – tie the 2 – greens together, one black dimmer switch wire to one of the two remaining house wires and the remaining black dimmer switch wire to the remaining house wire.

Step 7. Carefully push all the wires back into the switch box, this could be tight, be carefully not to pinch any of the wires. Attach the new dimmer switch with the (2) new screws provided and tighten. Attach new cover plate provided over the switch and secure.

Step 8. Turn the breaker back on in the main power panel and enjoy your new dimmer switch.