Dimmers reduce the amount of electricity your lights use when set below full brightness, which over time lowers energy consumption and can reduce your electric bill.
Replacing an existing light switch with a dimmer is a straightforward job many homeowners can handle. Follow the steps below—especially Step 1—to ensure a safe, clean installation. Dimmers are available at hardware stores in a variety of styles and price ranges. Read the installation instructions and match the dimmer type to your wiring before you buy.
STEP 1: Locate and turn off the fuse or circuit breaker that controls the light switch you are replacing.
If the breakers or fuses aren’t labeled, identify the correct one by turning the switch on and then turning off breakers or fuses one at a time. When the light goes off, that’s the correct circuit—leave it off while you work and make sure the others are on. Note: if you accidentally reset other breakers, check digital clocks or appliances that might need reprogramming.
STEP 2: Remove the wall plate and pull the switch from the wall.
Remove the two screws holding the cover plate, then remove the screws that secure the switch to the electrical box. Gently pull the switch out so you can access the wire terminals and the wires inside the box.
STEP 3: Determine the switch type.
This step is crucial. You must identify how the existing switch is wired so you can select and install the correct dimmer. Switches are typically wired as either a single-pole or a 3‑way configuration. A 3‑way setup is used when two switches control the same light. Even if only one switch controls the light, verify the wiring before proceeding.
– A single-pole switch has two insulated wires connected to two screws of the same color. Replace it with a single-pole dimmer.
– A 3‑way switch has three insulated wires connected to three screws. One of those screws (often a different color) is the common. Label the common wire so you can identify it when installing the new dimmer, and replace the switch with a 3‑way compatible dimmer.
STEP 4: Remove the wires from the old switch.
Loosen the terminal screws and disconnect the wires from the switch. Keep track of how each wire was attached.
STEP 5: Wire the new dimmer.
Start by connecting the green ground wire from the dimmer to the grounding conductor in the wall box or to the grounding screw inside the box. Then connect the dimmer’s wires according to the type you are installing:
– Single-pole: connect the dimmer’s black wires to the two hot wires you removed from the old switch (order does not matter for single-pole).
– 3‑way: attach the dimmer’s black or marked common lead to the wire you previously labeled as common. Connect the remaining dimmer lead(s) (often red) to the other traveler wires as specified by the dimmer manufacturer.
Use wire nuts (usually supplied with the dimmer) or approved connectors for all splices and ensure connections are secure.
STEP 6: Secure the dimmer and install the cover plate.
Insulate any exposed wires and make sure all connections are covered by wire nuts. Carefully tuck the wires into the electrical box so there is room for the dimmer mechanism. Fasten the dimmer to the electrical box with the mounting screws and then attach the cover plate.
STEP 7: Restore power.
Turn the circuit breaker or replace the fuse for the circuit you worked on. Test the new dimmer—if there’s no burning smell and the lights operate correctly, the installation is complete.
With dimmers installed, you can create the ambiance you want—dim the lights for a romantic dinner, relax with softer lighting, or save energy by reducing brightness when full light isn’t needed.