How to Change a Fluorescent Ballast

A fluorescent ballast is a device that creates the surge that causes the gases in a fluorescent light bulb to glow. Compact fluorescents that you simply screw into a socket don't require ballasts, but traditional fixtures that use long bulbs do. Without a ballast, sometimes called a starter, there is no illumination. A strong odor is usually the first indicator that a ballast is going bad. Always replace a bad ballast with exactly the same model. Anyone comfortable working with electrical writing can change a fluorescent ballast quickly and easily.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• Ballast
• Wire nut
• Nut driver

1. 
    

   Make sure the power to the fixture is turned off. Take off the cover and remove the bulbs by rotating them until the prongs at the ends of the bulb line up with the slots in the light bulb frame. Then gently slide the lamp, or bulb, out.

2. Locate the ballast and open the cover by rotating the tabs. The ballast is usually in the middle of the fixture.

3. Separate the wires that come out of the ballast from fixture wires at the wire nuts. If your light fixture doesn't have wire nuts, measure about a foot out from the ballast on each side and cut the wires there.

4. Remove the ballast from the fixture by unscrewing the nut or nuts that hold it in place.

5. Make a list of the wattage, length and number of bulbs in your fixture in case the clerk at the hardware store needs the information to choose the right replacement ballast. Take the list and the ballast you just removed to the hardware store. Replace the ballast with exactly the same kind of ballast.

6. Put the new ballast in the fixture by screwing the nut you removed from the old ballast into place. The wires at each end of the ballast should face the same colored wires in the fixture.

7. Attach the wires on the ballast to the matching wires in the fixture by stripping about 1/2 inch of insulation from each end and using wire nuts to join the ends..

8. Put the ballast cover on by holding it in place and turning the tabs. Replace the bulbs and put the fixture cover back on.

Tips & Warnings

• Let the light warm up for a minute or two the first time you turn it on. Fixtures with four bulbs may have two ballasts.
• Fluorescent bulbs are easy to break and create very sharp shards when they shatter.

Resources

• In-Depth Information on Fluorescent Fixtures
• Troubleshooting Fluorescent Bulbs
• Fluorescent Bulb FAQ