• Share:
How to Replace a Fluorescent Light Ballast

Replace the ballast when your fluorescent light flickers or makes an annoying hum. The repair will only take about 10 minutes.

By the DIY experts of The Family Handyman Magazine

  • COST
  • CostCost $20 - $100
  • close X

    New ballast prices range from $15 - $50. This is often more than the price of a new fixture! Consider replacing the fixture.

Replace the ballast in four steps.

When your fluorescent light flickers or makes a loud and annoying hum, a degrading ballast is the cause. The ballast takes in electricity and then regulates current to the bulbs. A typical ballast will generally last about 20 years, but cold environments and bad bulbs can decrease this lifespan significantly. You can get a new ballast at a hardware store or home center and install it in about 10 minutes. However, buying a ballast can be expensive, so consider pricing a brand-new fixture for comparison.

Start by flipping off the circuit breaker or unplugging the light. Remove the bulbs and open up the fixture as shown in Photo 1. There will be four to eight wires coming out of the ballast. Photos 2 and 3 show how to remove the old ballast from the fixture. Confirm that the new ballast matches the old one (photo below) and then install it as shown in Photo 4. After mounting the new ballast, replace the ballast compartment cover and bulbs, and it should be good for another 20 years.

Caution: Turn power off at the main panel before performing this repair.

Old and new ballasts

Old and new ballasts

Buying a New Ballast

Take the old ballast to the store with you. Compare the new and old ballasts to verify that the wiring diagrams, voltage and current match before installing the new ballast.

Back to Top

Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

    • 4-in-1 screwdriver
    • Nut driver
    • Wire stripper/cutter

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.

    • New ballast
    • Wire connectors

Comments from DIY Community Members

Share what's on your mind and see what other DIYers are thinking about.

1 - 8 of 8 comments
Show per page: 20   All

September 05, 2:44 PM [GMT -5]

My installation worked for 5 mins.and then the lamp went off. I installed all the wires as per the diagram. The philips ballast hast 2 red, 2 blue, 2 yellow, one black and one white. I wired each color to its own.
Why doesn't it work?

March 16, 11:06 PM [GMT -5]

After installing the new ballast, I turned on the light switch. The lights immediately came on. Stayed on for about 5 minutes and went out. What did I do wrong?

Anyone have an answer for the above question posted on May 28th?

March 11, 7:39 AM [GMT -5]

9 times out of 10 it's not the ballast thats failed but the tube or starter.
But if replacing a ballast, I would strongly advise replacing the old transformer ballast with a modern electronic ballast, advantages:
1) lamps start quicker without flickering
2) no more switch starter to replace periodically
3) 10% reduction on energy consumption = lower electricity bills
for reason (3) many corporations upgrade ballasts to electronic ones before end of life, as savings outweigh costs for lights that are on for long periods.

August 07, 11:21 AM [GMT -5]

I screwed up by taking down the entire ballast and sockets, to take ballast to store for replacement. I did not have trouble putting the sockets back on the side where the two red wires and the two blue wires were. The problem is with the other side. This is a two light system and I put the black and the white wires to the socket they came from. On the other side there are two yellow wires which I put back to that socket, but there is also two white wires(one in each side of that socket) and I cannot remember how they were attached. Now when I put the bulbs back in one bulb comes on and the other popped and blew something loose in the bulb. Please help me get this straightened out because I now have wife on my back,lol.

November 13, 1:51 PM [GMT -5]

Thanks for this tutorial. It was easy to follow. Thought we would have to replace the entire fixture, but a new ballast did the trick! Saved me about $80.

April 10, 5:20 PM [GMT -5]

How about something that describes how to retrofit one of the new electronic ballasts for the old magnetic types. I just attempted to follow the directions and schematics that came with the new (electronic) ballast, except that the directions (photos included) do not match up with the wire schematic that is on the ballast. Thumbs down for GE.

May 28, 2:10 PM [GMT -5]

After installing the new ballast, I turned on the light switch. The lights immediately came on. Stayed on for about 5 minutes and went out. What did I do wrong?

April 26, 10:15 PM [GMT -5]

I need to try this. I have some old fixtures in the basement that need replacing.

+ Add Your Comment

Add Your Comment

How to Replace a Fluorescent Light Ballast

Please add your comment

Log in to My Account

Log in to enjoy membership benefits from The Family Handyman.

  • Forgot your password?
Don’t have an account yet?

Sign up today for FREE and become part of The Family Handyman community of DIYers.

Member benefits:

  • Get a FREE Traditional Bookcase Project Plan
  • Sign up for FREE DIY newsletters
  • Save projects to your project binder
  • Ask and answer questions in our DIY Forums
  • Share comments on DIY Projects and more!
Join Us Today

Report Abuse

Reasons for reporting post

Free OnSite Newsletter

Get timely DIY projects for your home and yard, plus a dream project for your wish list!

Follow Us

Featured Product

Buy Now