Replacing the Ballast in a Fluorescent Light Fixture

fluorescent lights in office building
  • 1 hours
  • Intermediate
  • 50
What You'll Need
Wire nuts
Electrical tape

When a fluorescent light does not work, most people replace the bulb, but occasionally the ballast will need replacing as well. When new bulbs take an extended amount of time to light or never light up at all, it usually means your ballast needs replacing. The ballast regulates the flow of electricity to the bulbs, and when it fails, then bulbs will not light properly. Replacing the ballast in a fluorescent light is a relatively easy process and need not be intimidating for even the most novice do-it-yourselfers.

Use common safety precautions before beginning to work on replacing the ballast in a fluorescent light fixture.

Step 1 - Turn Off Electricity

Turn off the electricity to the fixture at the power breaker box. Before starting to work on the fixture, flip the light switch to make sure the electricity is turned off.

Step 2 - Remove the Shade

Climb on the ladder and carefully remove the plastic shade from the light fixture. Usually, you can accomplish this by pushing both sides of the shade together to pop it free. Other fixtures require you to unscrew a fastener, and other shades must be unhooked from the edges. Use care, as the plastic can break easily.

Step 3 - Remove Bulbs

Turn the fluorescent bulb slightly to loosen it from the socket. It should slide out freely when it is properly released. Gently set the bulb aside. Repeat for a second bulb if there is a second bulb in the fixture.

Warning: Fluorescent bulbs can explode, so put them in a safe place while you complete the ballast repair.

Step 4 - Remove Ballast Cover

In the light fixture, you will see a metal cover protruding into the light area. This is the ballast cover. Remove it by pushing the sides of the metal cover together or unscrewing the screws, whichever is required on your fixture. Pull the metal cover down and remove it, laying it aside in a safe place.

Step 5 - Disconnect Wires

Snip the wires that hold the existing ballast into place. Cut them off close to the old ballast. Using a utility knife, strip the wires to expose about 1/2 inches of bare wire.

Step 6 - Remove Ballast

Use the screwdriver to unscrew both of the side screws on the ballast. Remove the ballast and discard it.

Step 7 - Install New Ballast

Place the new ballast in the place of the old ballast.

Strip the ends of the wires on the ballast if they are not bare on the ends. Connect the wires, matching ground wires and black wires. Twist the wires together so that there is a complete connection. Put a wire nut over the wires and screw it on. Wrap electrical tape over the wire nut to secure.

After you have connected each of the wires, screw the ballast into place. Replace the metal cover over the ballast, and then reinstall the fluorescent bulbs. Finally, replace the light fixture shade.

Step 8 - Turn Power Back On

Turn the power back on at the breaker box. Turn the switch on to see if the light works correctly.