7 posts / 0 new
Last post
Wandrin
Fluorescent light

My husband put in 2 new ballasts in our fluorescent kitchen light. One ballast has one tube and one has two tubes. All three tubes in the light are the same brand and type. On the ballast that has two tubes, one of the tubes is noticeably dimmer than the other two. Is there a reason for this?

dj1
Re: Fluorescent light

Not all ballasts created equal. More info is needed.

How old are your fixtures? Do they use magnetic ballasts or electrical ballasts? Did you replace ballasts with the same kinds?

How do you find out? the ballasts should have stickers on them.

Wandrin
Re: Fluorescent light

The fixture is 40 years old. The old original ballasts were just replaced with electronic ballasts. One tube of the two tube ballast circuit is normal the other is noticeably dimmer. Both tubes are the same brand and are new. Thanks.

dj1
Re: Fluorescent light

For electronic ballasts use T12 bulbs.

Your 40 year old fixtures had magnetic ballasts. Generally, with such old fixtures we replace the whole fixtures, not just the ballast. That's the idea.

Fencepost
Re: Fluorescent light

Make sure the tubes are seated properly. If you look at the metal endcap, there are two dimples on the edge located perpendicular to the pins. Make sure that the dimple lines up with the slot in the socket. If not seated properly, it can prevent the tube from lighting fully.

Replacing the ballast isn't a BAD idea. There's no reason to replace the entire fixture if you like it and a replacement of that style is not available for purchase. I recommend going to T8 tubes (1" dia.) rather than T12 (1+1/2" dia.). The T8 tubes are more efficient and brighter. However, ballasts are not interchangeable; if it's designed for T12 you must use T12 tubes; if it's designed for T8 you must use T8 tubes. (And there are ballasts available that will power three tubes with one ballast.)

A bit of trivia: the T-number (T12, T8, T5, etc.) indicates the diameter of the tube, in eighths of an inch. T12 is 12/8" or 1+1/2"; T8 is 8/8" or 1"; and T5 is 5/8".

Mastercarpentry
Re: Fluorescent light

Most of the time an entire new fixture with lamps can be installed for essentially the same price as new ballasts. What little may be saved in buying ballasts is lost in the install time versus just putting a new pre-wired fixture in more quickly. And with the new fixture everything is new and hopefully it will all last a lot longer!

Phil

Re: Fluorescent light
Mastercarpentry wrote:

Most of the time an entire new fixture with lamps can be installed for essentially the same price as new ballasts. What little may be saved in buying ballasts is lost in the install time versus just putting a new pre-wired fixture in more quickly. And with the new fixture everything is new and hopefully it will all last a lot longer!

Phil

True Phil and the physical spacing between the lamp and the fixture may be too great for reliable service.

Flourescent lights have many such restrictions, including the need for the enclosure to be grounded.

TV Listings

Find TV listings for This Old House and Ask This Old House in your area.