Silencing the Buzz, Hum of Fluorescent Light Fixtures

Fluorescent light fixtures are more efficient and cheaper to run than incandescent. But some fluorescent fixtures buzz or hum, and they take a long time to start when temperatures fall much below balmy.

If your fixtures have these problems, a failing ballast--the component that gives the lamps the power boost they need to start--might be the cause. If the light flickers or won’t work at all, the ballast is probably shot.

Replacing a faulty ballast isn’t difficult, but it’s essential to match the ballast to the lamps in your existing fixture.

That 4-foot, two-lamp fixture in your garage or basement, for example, likely uses T12 lamps and a matching electromagnetic ballast, says Jeff Goldstein of Lamar Lighting in East Farmingdale, N.Y.

(The industry measures the diameter of lamps in one-eighth-inch increments, so a T12 is 1 1/2 inches in diameter.) If you don’t know which ballast to buy, take your old one to an electrical supply house.

Magnetic ballasts are readily available and cost about $16. If you want to eliminate loud buzzing noises, upgrade to an electronic ballast (about $28), which is quieter and more efficient. Electronic ballasts are standard on newer T8 fixtures, according to Goldstein, but it might be more difficult to find them for older T12 lights.

Also consider the location of the fixture. Standard ballasts work best in temperatures above 50 degrees. If lamps are in colder areas, buy cold-weather ballasts, which can fire up the lamps in temperatures as low as zero.

To remove the ballast, cut power to the circuit at the circuit breaker panel. It’s safer to turn the circuit breaker off at the main panel than it is to rely on a wall switch that might be wired improperly.

Most corded garage or shop fixtures are hung from the ceiling by lightweight chain, so it’s simple to take a fixture down for repairs. Take out the lamps, then remove the access panel on the fixture and disconnect the black and white wires from the power supply.

Next, clip the three pairs of wires emerging from the ballast; there should be two reds, two blues and two yellows. Reconnect leads on the new ballast with wire nuts; the light should work fine once again.

One tip: Reconnect each pair of colored wires individually. The ballast won’t work properly if you gang together all four red wires, for example, and connect them with a single wire nut.

New federal energy standards will eliminate T12 lamps and ballasts in 2005, according to Harold Thompson of Advance Transformer Co., a major ballast maker. If you decide to switch out a T12 ballast for a more efficient T8 before then, don’t forget to change the lamps too.

If you’re tired of the harsh, gray light given off by standard fluorescent lights, look for a lamp with a higher Color Rendering Index or CRI.

The CRI is a relative scale that rates light sources on a scale from 0 to 100 (sunlight is rated at 100). Lamps with a higher CRI make people and objects look more realistic. Manufacturers adjust the CRI by tinkering with the mix of phosphors that coat the inside of the lamp. A standard 34W “cool white” lamp has a CRI of 62, but lighting stores and home centers also stock lamps rated up to 90.

The only downside is that you will pay two or three times as much per lamp for that great-looking light.