How to Change the Ballast on a Fluorescent Light Fixture

Changing the ballast on a fluorescent light fixture is a relatively straightforward process that can breathe new life into old fluorescent lights. With some basic hand tools and a replacement ballast, you can swap out the old ballast for a new one in just a few steps.

What You’ll Need

To change the ballast, you’ll need:

  • Replacement ballast compatible with your fluorescent light fixture
  • Phillips screwdriver
  • Needle nose pliers
  • Wire cutters/strippers
  • Electrical tape
  • Ladder or step stool to reach light fixture

Safety first! Be sure to turn off power to the light and double check with a voltage tester before working on the electrical.

Removing the Old Ballast

Follow these steps to remove the existing fluorescent light ballast:

  1. Turn off power to the light fixture at the breaker box and verify power is off.
  2. Remove the light fixture cover and fluorescent tubes.
  3. Locate the ballast, usually mounted to the interior of the fixture. There may be a cover that needs removed first to access it.
  4. Remove any screws or fasteners securing the ballast and detach any wiring connectors.
  5. Cut away any zip ties bundling the wires to free the ballast.
  6. Disconnect the input and output wires from the old ballast. Make note of where each wire was connected.
  7. Remove the old ballast and discard appropriately.

With the old ballast removed, it’s time to install the new one.

Installing the New Ballast

Follow these steps to safely install the replacement ballast:

  1. Match up the wires on the new ballast to the old ballast wiring. Input and output wires are often different colors.
  2. Connect the input wires from the fixture to the input wires on the new ballast. Secure with wire nuts.
  3. Connect the output wires from the ballast to the fluorescent light wires. Secure connections with wire nuts.
  4. Use electrical tape to cover any exposed wire.
  5. Mount the new ballast securely in the same location as the old one. Screw into place if needed.
  6. Neatly bundle all wiring with zip ties or electrical tape.
  7. Reinstall fixture cover and fluorescent tubes.
  8. Carefully restore power and test that the light is working.

That’s it! With a few tools and safe electrical practices, you can swap out a faulty fluorescent fixture ballast for a new one. The light should now shine bright and new.

FAQs About Changing the Ballast

Here are answers to some frequently asked questions about changing fluorescent light ballasts:

How can I tell if the ballast is bad?

Some signs your ballast has failed:

  • Light flickers or makes buzzing noises
  • Light is dim or only one tube works
  • Tubes take longer than normal to warm up
  • Tubes don’t turn on at all

Where can I buy a replacement ballast?

Hardware stores, home centers, electrical supply stores, and online retailers typically carry replacement fluorescent light ballasts. Make sure to get one rated for your specific fluorescent fixture.

Is changing the ballast dangerous?

Working with electrical wires can be dangerous if proper precautions are not taken. Always turn off power at the breaker, verify it’s off with a voltage tester, and use safe wiring practices. If you are uncomfortable working with electrical, it’s best to call an electrician.

What tools do I need to change the ballast?

Basic hand tools like a screwdriver, pliers, wire cutters/strippers, ladder, and electrical tape are needed. A voltage tester is critical for verifying power is off.

How do I dispose of the old ballast?

Fluorescent light ballasts contain hazardous materials and should not be thrown in the regular trash. Take old ballasts to an e-waste recycling facility or hazardous waste collection site.

Can I just replace the starter instead?

For magnetic ballasts, replacing the starter may provide a temporary fix. But it’s best to replace the entire aging ballast with a new electronic ballast for better efficiency and performance.


Changing out a malfunctioning fluorescent fixture ballast brings new life to old lighting. With a compatible replacement ballast, some basic tools, and safe electrical practices, you can complete this repair yourself. Be sure to properly dispose of the old ballast, then enjoy the brightly lit fluorescent tubes. Call an electrician if ever in doubt when working with electrical wiring.