Fluorescent Light Help

[Arthur Shapiro]

The kitchen has a dropped ceiling with two pairs of standard 4-foot bulbs - I guess that's what is called T12. This fixture has never been very reliable in the 20 years I've owned the house. Bulbs don't last as long as they should, and on colder winter mornings, while the heater is still warming up the house, they often take several minutes to come on.

The last straw came two days ago when a two-week-old pair of Phillips bulbs no longer would light, period. One of those tubes already has blackened ends. The other pair in this fixture is working OK.

What is likely to have failed to cause such an early failure on these bulbs? I assume the ballast, but would like an expert to confirm. I'm interested in purchasing electronic replacements, while realizing they are more expensive than traditional magnetic ballasts, but an intimidated by unfamiliar concepts such as "ballast factor".

Can anyone provide practical troubleshooting and replacement/selection advice so I can purchase the correct pair of ballasts?

Art

[Chris Friesen]

While you're at it, you might consider switching to T8 bulbs. You'll need to replace the bulb holders as well, but you'll get electronic ballasts automatically.

Chris

[bob kater]

[Joe]

Doing a value analysis with new fixtures will quickly lead you to conclude that the old fixture repair is a hopeless proposition. Avoiding the off shore super cheapies at the box stores ought to get you some attractive, modern, and reliable lighting. Of course, if you like to tinker, that's a whole different thing. HTH

Joe

[Don Klipstein]

Many residential dual-T12 4-foot fixtures have some call the "residential grade" ballast. It is maybe 1.5 inches shorter than a "full size" dual-4-footer fluorescent lamp ballast. I call those ballasts "stool specimens" to put it politely.

Ballast factor is ratio of light output using the ballast in question to light output on a "reference ballast", which is some standard used to determine the catalog figure for rated light output.

Most ballasts for which ballast factor is made known are for T8 (1 inch diameter) bulbs. T8 ballasts tend to be electronic and better. I would recommend replacing the ballast with an electronic one for T8, and use T8 bulbs.

As for a usual dual-4-footer rapid start magnetic ballast becoming prone to blacken the ends of the bulbs quickly: The output series capacitor is probably shorted. The ballast can easily overheat from this. The ballast needs to be replaced.

- Don Klipstein ( [e-mail])

[Don Klipstein]

T8 and T12 bipin fluorescents take the same lampholders.

- Don Klipstein ( [e-mail])

[Don Klipstein]

I prefer to change the ballast myself because too many fluorescent fixtures sold in retail establishments for use in homes (or home garages) have what many call "residential grade" ballasts, which I call "stool specimens".

- Don Klipstein ( [e-mail])

[larry]

I've had it with 22" & 32" circs and 6"-48" T whatever. When ANY part fails, I pull the guts and add 1-4 standard edison base sockets, and screw in 5w to 32w CFL's as needed.

Cost less that replacing the bad part and my box of $2

5/13/24w cfl's (HD 6 & 8 packs) will now replace everything.

-larry / dallas

[Don Klipstein]

I have seen quite a share of problems and insufficiencies with fluorescents 22 watts or less, especially less than 15 watts, and ones between 22 and 32 watts are a bit oddball and expensive.

4-footers are less expensive and 2-foot F17T8 I have been quite happy with. My main problems with 4-footers are that some ballasts for F40T12 are lousy, and F34T12 can be "cranky", especially in cold or with a subpar ballast.

Use of "true 40 watt" F40T12 or better still 17 and 32 watt T8 with decent ballasts should do well where the fixtures fit well and look good.

A 4-footer usually costs less than a CFL and usually outlasts a CFL, is more efficient than a CFL and has less of warmup issues than a CFL. What CFLs are good for is where a good linear fixture is impractical, too big or does not look good.

- Don Klipstein ( [e-mail])