If you have a light fixture that's buzzing, the constant hum might irritate and distract you. It also might mean that something is wrong with the light fixture, bulb, or switch.
A buzzing light fixture can affect different types of lights: LED, fluorescent, CFL, and incandescent. Reasons range from mismatched dimmer switches and light bulbs to old light ballasts that need replacing. You can fix most of these light fixture buzzing problems by yourself.
LED Light Fixture Is Buzzing
When LED light fixtures are humming or buzzing, the reason is usually an incompatibility between the LED light and the dimmer switch. This is typically not dangerous.
Test if LED Dimmer Is Causing the Buzzing
The best way to find out if the dimmer switch is the reason for the buzzing is to temporarily take the light off of the dimmer switch.
One way to do this is to first turn off the circuit breaker, remove the wiring from the dimmer, and connect the wires to a regular, non-dimming switch. Another way is to leave the dimmer switch in place, but remove the two hot wires (usually red or black) and wire them together with a wire nut.
If the LED light stops buzzing, you'll know the dimmer switch is at fault.
Properly Size the Dimmer Switch to the LED Light
If you switched from an incandescent bulb to an LED bulb but left the old dimmer switch in place, it will need to be replaced with a compatible dimmer switch.
Before you buy a new switch, consult the LED bulb's instructions. Most manufacturers publish lists of compatible dimmer switches. Generally, you'll need a CL dimmer, a LED+ dimmer, or an ELV dimmer switch.
Fluorescent Light Fixture Is Buzzing
All fluorescent lights have a faint buzzing sound to some degree. All ballasts—fluorescent light fixtures' controlling mechanism—will have a low hum, but only if you get close to it. When the buzz is audible from the room, it's time to fix the light.
Adjust the Fluorescent Tubes
Fluorescent tubes can become loose or partially loose in their holders, possibly causing buzzing. After removing the diffuser (the clear acrylic cover), check each tube to make sure that it is tight. To reseat a tube, rotate it 90 degrees (a quarter-turn) in either direction.
Replace the Light Ballast
The ballast is the magnetic or electronic controller inside the fluorescent light that regulates the flow of electricity to the fluorescent bulbs. In many cases, the ballast has become old and worn out and needs to be replaced.
The black and white wires are line (or hot or powered) wires that come from the electric service panel and feed into the fixture's ballast. Blue and red wires run to the fluorescent tubes. Yellow wires run out of tubes and back into the ballast.
- Turn off the circuit.
- Remove the diffuser and the tubes.
- Remove the housing over the ballast.
- Disconnect the line (or power) wires.
- Cut the rest of the wires.
- Remove the ballast with a cordless drill or a driver.
- Install the new ballast.
- Connect power wires and remaining color wires (blue to blue, etc.) with wire nuts.
- Reinstall the ballast housing.
- Reinstall the tubes and light cover.
It is now possible to buy ballast-free LED tubes that replace fluorescent tubes. There is a small bit of rewiring to eliminate the ballast but the instructions that come with the tubes are easy to follow.
Fix the Metal Housing or Diffuser
Fluorescent lights are made of sheet metal and plastic and can become loose or damaged over time. A minor buzz that otherwise might be tolerable will be amplified by a loose or broken light fixture.
Remove the diffuser. If it is cracked, replace it with a new one. Reinstall the diffuser and make sure that it is tightly in place.
Replace the Fluorescent Light Fixture
Replace the light fixture entirely if replacing the defective ballast is not feasible. Replacement two-lamp ballasts cost between $15 to $35. New two-lamp fluorescent light fixtures cost from $30 to $60. So, unless you need to replace several ballasts, it may be best to entirely replace the fluorescent light.
If the fixture housing is bent or broken, it should be replaced. Twisted, warped, or bent sheet metal is difficult to straighten out.
CFL Light Fixture Is Buzzing
CFL bulbs—those spiral bulbs that twist into light sockets—are fluorescent lights. Just like ceiling-mounted fluorescent light fixtures, they too contain a tiny ballast device that can sometimes buzz.
Most CFL bulbs should not be on dimmer switches. Remove and replace buzzing CFL light bulbs.
Incandescent Light Fixture Is Buzzing
Incandescent bulbs were largely phased out, beginning in 2011. If your incandescent light is buzzing, likely the filament is vibrating. Moving the light off of a dimmer switch may help. The best thing, though, is to replace the bulb with an energy-saving LED bulb.
Frequently Asked Questions Regarding CFLs and Dimming. National Electrical Manufacturers Association