Troubleshoot your light fixtures to determine what is causing your fixture to make a buzzing sound. A buzzing sound could mean your fixture is failing or the parts of the fixture have loosened. The unseen expansion and contraction caused by electricity can actually loosen the light bulbs, which can create a vibration, loosening other parts of the fixture. Incorrect device wiring can also create a buzz in a fixture. Be prepared to examine the electrical wiring when trying to determine what's causing your fixtures to buzz.
Check your fluorescent fixture for possible causes of light buzzing. A fluorescent fixture rated for indoor applications can buzz if installed outside or in the garage. A shop or garage fluorescent fixture ballast makes a louder noise than an interior-rated fixture, creating a buzzing sound.
Confirm that the ballast in your fixture isn't loose or burnt. Locate the ballast beneath the centre panel on the fixture. Turn off the breaker that powers the fixture inside the main breaker panel. Remove the light cover from your fixture and remove the light bulbs.
Pull the metal cover from the centre of the fixture to expose the ballast. Depending on the manufacturer, the cover is held by screws or metal tabs on the metal cover inserted into slots on the fixture. Tighten the screws holding the ballast to the fixture. A charred or leaking ballast requires replacing the ballast or the fixture.
Check the dimmer for your fluorescent fixture to confirm that it is rated for fluorescent lighting. Turn off the electrical power at the breaker panel and remove the cover from the dimmer switch. Look on the face of the dimmer switch to see if it is marked for incandescent or fluorescent applications. An incandescent dimmer causes your fluorescent fixture to buzz, and you need to replace it with a fluorescent dimmer or a regular single-pole light switch.
Turn off the power to the buzzing light fixture at the breaker panel.
Remove the light switch cover to see if your light is attached to a dimmer or to a fan speed control. The printing on the face of the switch indicates whether it's a speed control for a fan or a lighting control.
Replace the fan control with a dimmer switch or a single-pole light switch, if you discovered your light fixture is installed on a fan control. Inadvertently attaching a fan speed control to a light fixture causes the light fixture to buzz.
Find the wattage rating on your dimmer face to confirm the wattage rating isn't exceeded by the total wattage of your light bulbs in the fixture. Light dimmers are available in 600- and 1000-watt ratings; exceeding those ratings causes your fixture to buzz.
Replace your light bulbs with lower wattages or replace your dimmer switch with a newer model. These changes can help in diminishing or eliminating the buzz.