How To Replace The Ballast On A Fluorescent Light Fixture

If you have fluorescent lighting, the ballast will wear out at some point. The ballast is the small black box that produces the current and voltage needed to operate the light.

A buzzing noise or flickering bulbs are common signs of a bad ballast. Replacing a bad ballast is easy for a novice do-it-yourself person. Here are some tips on how to replace a bad ballast in a fluorescent light.

Shut Off Power

Shut off power to the room you're working in before making any electrical repairs. If you don't know which breaker shuts off power to the room, switch each breaker off with the lights on. To make certain power is off, try turning on the lights in the room; if they don't turn on, you did this right. To ensure no current is going to the fixture, test it with a voltage meter.

Remove the Bulb and Cover

Climb a ladder and remove the cover from the fixture to expose the wiring and ballast. Covers may be attached with screws, hooks, or attachments that pop off by pushing on the sides. Rotate the metal tabs slightly toward you on the bulbs until they slide out.

Be careful not to break fluorescent bulbs because florescent bulbs have small amounts of mercury. Mercury is a toxic substance and breaking a bulb will send it into the air. It could enter your bloodstream, especially through cuts, and cause you damage.

Try Replacing Tubes and Starter 

You may want to try replacing the tubes or starters in the fixture before removing the ballast, but tubes that stop working at once usually mean the ballast is bad. An older fluorescent light fixture commonly has a starter, a small object shaped like cylinder at the end of the fixture. If new tubes or starters don't fix the problem, proceed to replace the ballast. 

Replace the Ballast

You will see several colored wires after you expose the ballast. All of these wires will need to be disconnected. If there are wire nuts, twist them off. Otherwise, cut the wires close to the ballast with wire cutters and expose 1½ inches of bare wire with a utility knife.

Detach the old ballast by removing the nut with a wrench and buy a replacement. Install the new ballast by snipping the wire ends if they aren't bare. Connect the wires, secure the wire connectors with electrical tape, and twist them to ensure complete connection. Reconnect the ballast, ballast cover, bulbs, and fixture cover. Turn the power back on to test.

Replacing the ballast should help your light stop flickering and making noise. If your repairs don't work, you will need an electrician to find the issue.