Dimmer switches are a great way to bring down the lights and set the mood—but nothing kills the mood faster than a buzzing dimmer switch.
Whether the buzzing is coming from the lightbulb or from the dimmer switch itself, the fix is usually simple, inexpensive, and fast. In no time at all, you'll have a light that you can dim down—without that annoying buzz.
What Is a Dimmer Switch?
Why a Dimmer Switch Might Be Buzzing
Dimmer switches don't actually slow the flow of electricity. Instead, they rapidly switch the electricity on and off—up to 120 times per second—so quickly that the eye cannot register it. This rapid pulsation helps to partially explain why the dimmer switch or bulb is buzzing.
If the lightbulb controlled by the dimmer switch has filaments, the undulating current may be causing the filaments to vibrate. This vibration results in a buzzing or humming sound.
If you can trace the buzzing to the light, not the dimmer switch, this is likely the cause.
Dimmer Switch Needs to Be Upgraded or Replaced
If the buzzing is coming from the dimmer switch, the switch may be improperly sized for the light. The switch may need to be removed and replaced.
Always turn off the electricity to the dimmer switch and light by shutting off the power at the circuit breaker before beginning work. Test wires with the non-contact voltage tester before working on them.
Equipment / Tools
- Voltage tester
- Phillips and flat-head screwdrivers
- Cordless drill with driver bits
- Wire ripper (optional)
- Wire stripper
- Lower wattage bulbs
- Rough service bulbs
- Dimmer switch
Turn off Switch and Remove Bulb
Turn off the power to the light fixture at the switch. Safely access the light fixture on a step ladder. Remove the lightbulb.
Change Bulb for Lower Wattage Bulb
Replace the bulb with a lower wattage bulb to place less demand on the dimmer switch.
Calculate the number of light fixtures served by the dimmer switch and multiply that number by the wattage per bulb. Multiply that by 1.25 to arrive at the correct dimmer wattage choice.
Change Bulb for Rough Service Bulb
If stepping down the wattage doesn't work, try changing out the bulbs for rough service bulbs.
Rough service lightbulbs are designed to be used in garages, shops, and other areas of heavy vibration. Rough service bulbs have more wire within the glass to help protect the filament.
Shut Down Power at Circuit Breaker
Access Dimmer Switch
With the flat-head screwdriver, remove the faceplate on the dimmer switch box. Before touching anything in the box, run the voltage tester against the dimmer switch's terminals. Make sure that you first verify that the voltage tester is working by trying it out on a known working outlet.
Remove the switch mounting screws by running the cordless drill with a driver bit counter-clockwise. Extract the switch from the box by holding it by the mounting straps. With full access to all of the attached wires, once again test the wires with the voltage tester. If there is no voltage, proceed.
Replace Dimmer Switch
Detach all of the wires from the dimmer switch. With the wire stripper, snip off any mangled wire ends. Re-strip the wire coatings to expose bare wire. If necessary, rip back any cable sheathing to expose more wire.
Two hot or live wires (usually black) enter the box. Attach one of those hot wires to the black wire on the dimmer switch. Attach the second hot wire in the box to the dimmer switch's other hot lead (usually black or red). Attach the green wire on the dimmer switch to the bare copper (sometimes green) ground wire that enters the box.
Double-check any wires attached with wire nuts. No bare copper wire should be exposed. If so, twist off the wire nut, snip a tiny bit off of the end of the wires, then attach the wire nut again.
Attach the dimmer switch to the box with the mounting screws. Attach the faceplate with the flat-head screws. Turn on the circuit breaker and test the light.
When to Call a Professional
When the dimmer switch itself is buzzing and there is also a crackling sound or a burning smell, this may indicate electrical arcing, a dangerous condition. Shut down the current at the service panel by turning off the circuit breaker and call an electrician.