Home Improvement Stack Exchange is a question and answer site for contractors and serious DIYers. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

We have fluorescent lights in our office and someone said that the ballast was bad. How can you replace a ballast?

share|improve this question
Is there an unpleasant smell near the light? We had a similar problem in our office, and it was diagnosed as a bad ballast. Once it was replaced, the smell went away. – Doresoom Oct 26 '10 at 18:13
I don't notice an unpleasant smell, just that the lights won't work. – divided Oct 26 '10 at 19:26
up vote 8 down vote accepted

Before attempting to replace the ballast, I'd check to make sure it wasn't the bulbs first. If they're blackened at the ends, then it's the bulbs.

Otherwise, it may be the ballast.

First, cut power to the light by flipping the breaker. I'd check to make sure you got the right circuit by flipping the light switch on and off afterwards.

Next, open up the fixture and remove the bulbs. There's usually a center section of the fixture that is held in place by several flanges. Squeeze the center section to remove it.

The ballast should be inside - it looks like a rectangular box. Unscrew the wire nuts attaching it to the fixture. (I replace them on the exposed wire ends afterward just for a little extra safety.) Un-bolt the ballast from the fixture.

Take the ballast to a hardware store and get a matching replacement.

Reverse and repeat.

If you want pictures, here's a tutorial with the same basic approach.

Also, here's another resource that suggests replacing the entire fixture may actually be cheaper.

share|improve this answer
Great answer, thanks! – divided Oct 26 '10 at 19:26

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.