How to Fix a Buzzing Dimmer Switch

Buzzing dimmer switch being pressed

The Spruce / Kevin Norris

Project Overview
  • Working Time: 10 - 20 mins
  • Total Time: 10 - 20 mins
  • Skill Level: Beginner
  • Estimated Cost: $10 to $20

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?

A dimmer switch is an electrical light switch that allows you to raise or lower the brightness of a light by sliding a lever, touching a screen, or turning a knob. A dimmer switch can also turn a light on or off.

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.

Filaments Vibrating

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.

Safety Considerations

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.

What You'll Need

Equipment / Tools

  • Voltage tester
  • Phillips and flat-head screwdrivers
  • Stepladder
  • Cordless drill with driver bits
  • Wire ripper (optional)
  • Wire stripper

Materials

  • Lower wattage bulbs
  • Rough service bulbs
  • Dimmer switch

Instructions

Materials and tools to fix a buzzing dimmer switch

The Spruce / Kevin Norris

  1. 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.

    Dimmer switch turned off to access light fixture

    The Spruce / Kevin Norris

  2. 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.

    Tip

    For example, if your dimmer rated at 375 watts currently serves three 100-watt bulbs, try changing them out for 75-watt bulbs.

    Low wattage bulb replaced in light fixture

    The Spruce / Kevin Norris

  3. 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.

    Rough service bulb inserted into light fixture

    The Spruce / Kevin Norris

  4. Shut Down Power at Circuit Breaker

    If the previous steps don't help, try changing out the dimmer switch. Shut off the power to the dimmer switch by shutting off the circuit breaker at the electric service panel.

    Circuit breaker shut off in service panel

    The Spruce / Kevin Norris

  5. 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.

    Faceplate removed from dimmer switch with flat-head screwdriver

    The Spruce / Kevin Norris

  6. 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.

    Stripped ends of hot wires connected to dimmer wires

    The Spruce / Kevin Norris

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.