Fluorescent Light

The most popular option to light large areas of buildings. They come in a variety of connection types and power ratings.

12 Questions View all

Fluorescent lights dim and flashing

I have a fluorescent light fixture that uses two 40-watt 4' long tubes. It has recently started acting strange. When first turned on, it works fine for a minute or two, then one of the tubes becomes dim and the other becomes dim and flashing. It's not the tubes, as I've replaced those and nothing changed. Someone suggested it might be the ballast. I'm not exactly sure exactly how old the fixture is, but I'd guess it's at least 10 years old and has been used daily for that entire time. Is the problem caused by the ballast, and if so is that something that can be changed, or should I just buy a new fixture?

Answered! View the answer I have this problem too

Is this a good question?

Score 4


An update: I was able to get a replacement ballast at Home Depot. The bad news is the ballast was $18.49, only $1.50 less that a whole new fixture. It took about half an hour to install the replacement ballast. The replacement was successful and the lights are working great now. In my fixture there were eight 18 gauge wires that you have to cut and then attach to the new ballast. I used wire nuts to connect the wires, so it'll be a little easier to replace the ballast again in the future.

by Luke Soules

Add a comment

3 Answers

Chosen Solution

The ballast is causing your problem, and it can be changed. You need to remove the original ballast, (after you shut off the circuit breaker) and take it to a lighting place or electrical supply house. Better yet, get the numbers off the ballast first and call. It may take them a little while to cross reference the part number, but they will find you a suitable replacement.

With any luck, the replacement ballast will be the same size as the old one. If it is not, you will need to find a way to secure it to the old fixture. Perhaps you will need to drill new pilot holes and use sheet metal self tapping screws. Rewire the light if you have to, plug in the new ballast, reset the breaker and you should have bright consistent light.

Otherwise, for a few dollars more, you can get yourself a new light fixture

Was this answer helpful?

Score 3
Add a comment

Annoyingly true that sometimes it's cheaper to replace whole fixture than the ballast. Arrgh.

Was this answer helpful?

Score 2


That's what I'm afraid I'll find. Home Depot sell the whole fixture for only $20, but at least online they don't list the ballasts separately. Hopefully I can replace just the ballast, even if it costs as much as a new fixture.

by Luke Soules

That's true, that was my experience also.

by 040304

I was able to get a replacement that fit in the same mounting tabs as the original ballast. It was wider and taller than the original, but the same length.

by Luke Soules

Luke, Well how much did the ballast cost? Did it fix the damned problem fixture?

by Ricardo Furioso

The ballast was $18.49 at Home Depot. It did fix the issue completely, and was a lot less wasteful that throwing the entire fixture away.

by Luke Soules

Add a comment

If all above fails (which probablywon't) get a new transformer.


Was this answer helpful?

Score 0
Add a comment

Add your answer

Luke Soules will be eternally grateful.

View Statistics:

Past 24 Hours: 26

Past 7 Days: 167

Past 30 Days: 906

All Time: 46,758