I have a string of three under-the-counter fluorescent lights.
The first one won't come on. It's not the tube, because when I replace it with a working tube, it still won't come on.
Both ends of the tube get hot, but there's no light.
Any guidance or experience welcome.
replace the starter if it has one looks like a little barrel and is aluminum, push and twist to remove it Clark...
If it's a relatively new fixture, it won't have a starter, but it will have a ballast transformer. Open the fixture, check all connections, if nothing is loose, replace the ballast
>I think that's what it is -- Iballast.
'll go to a lighting store as soon as they reopen after the holiday weekend.
Do the working units get hot? If so, you may want to consider replacing all ballasts with electronic units. Most likely yours are conventional ballasts that use transformers. They get hot, hum and flicker. Electronic units don't. If you replace just the bad unit with an electronic one, the others won't be as bright because electronic ballasts are more efficient, therefore more light and less heat.
Ballast. Before you buy one, check the price of a new fixture as it is often cheaper to replace the whole thing.
On 7/4/2008 12:04 PM Edwin Pawlowski spake thus:
Maybe not cheaper, but possibly a hell of a lot easier to replace the whole fixture.
Have a current client with exactly the same problem: one of her under-shelf lights doesn't work even with known good bulbs. I'm currently trying to track down a ballast, based on what I copied off the old one, and think I've found one, but it took some doing. Nothing in the Grainger catalog, and both Ace stores I called said they had nothing; one suggested going to *their* supplier, a "real" electric supply house, which I did, and they think they've found one. At about $25, it's definitely going to be cheaper to just replace the ballast.
This is a non-trivial exercise. The light in question is an oddball one: two T5 lamps, but they're different sizes (F5 & F13). The ballast is an itty-bitty electronic one, so size is important.
I wonder how much searching it would take to find a replacement for the whole light fixture ...
Is there a starter? That is usually a cylindrical "can" about 3/4 inch wide, 1-1/2 inches tall. Twist it something like 1/4 turn CCW (when viewing the top of it), then comes out.
Chances are it is an FS-2 type, available at most hardware stores and home centers.
Bad bulbs are hard on starters, and bad starters are hard on bulbs. If a bulb and a starter both spent at least several hours trying to get you light while one was bad, the other may have become bad. You may need to replace both at the same time.
Meanwhile, if you can't get the fixture working, it is a good idea to pull either the bulb or the starter. If the starter "is stuck" and the bulb is glowing only at the ends (orangish or an orangish-pinkish modification of normal color, or 1 of each at each end), then the ballast is conducting increased current and could be running hotter than usual. They are supposed to withstand this, and I would think that UL listed ones had samples tested to satisfy UL that they are safe when this happens, but I know of one that failed badly from this after a couple of days. It started a fire in an apartment building elevator.
Meanwhile, pulling either the bulb or the starter prevents any ballast heating from stuck starters. Also, it is safe to see if things work - ballasts don't overheat quickly.
- Don Klipstein ( snipped-for-privacy@misty.com)
I would advise *everyone* against getting oddball hard-to-replace light fixtures.
I would also advise *everyone* against getting or specifying light fixtures that require bulbs so oddball as one I never heard of - F5T5. When buying a light fixture, go for ones that take bulbs available from multiple suppliers of more than one kind, and when bulbs of more than one brand are available. Preferably get fixtures if replacement bulbs of at least 1 preferably at least 2 of the "Big 3" brands (GE, Philips and Sylvania) are available.
There are specialty lighting devices where the bulbs are mostly not made by the "Big 3". There are also fixtures with proprietary bulbs. In those cases, bulbs will cost more.
Try to get fixtures with *more common* bulbs that are available at least at both Lowes and Home Depot *and* of "Big 3" brand. That makes getting replacement bulbs easier. It also makes getting replacement ballasts less difficult.
If you want replacement ballasts and replacement bulbs to be really easy, get fixtures that take bulbs of these kinds:
F15T8 (15 watt 18-inch 1 inch diameter) F15T12 (15 watt 18-inch 1.5 inch diameter) F17T8 / FO17 (17 watt 2-foot 1 inch diameter) F20T12 (20 watt 2-foot 1.5 inch diameter) F32T8 / FO32 (32 watt 4-foot 1 inch diameter) F34T12 (34 watt "energy saver F40" 4-foot 1.5 inch diameter) F40T12 (40m watt 4-foot 1.5 inch diameter)
Get replacement ballasts from those electrical supply shops of the kind that electricians/contractors go to. The ballasts tend to be better there. Bring the old ballast with you, and have a note with you if the fixture has provisions for ballasts of more than one specific length. Many lower cost 4-foot fixtures have shorter "residential grade" ("stool specimen") ballasts but also provisions for longer ones often referred to as "commercial grade".
For new fixtures, try to prefer F17T8 and F32T8 above the others. The bulbs in those are normally madw ith longer-life higher-efficiency phosphors whose lowest color rendering index grade has color rendering index in the upper 70's. Note that CRI above 86 tends to require severe compromise in light output and efficiency, but these bulbs have fair availability with CRI in the mid 80's with uncompromised light output. Ballasts for these tend to be electronic - better. Still, get replacement ballasts from electrical/lighting supply shops when you can to have a better chance at getting "the good stuff".
- Don Klipstein ( snipped-for-privacy@misty.com)
On 7/4/2008 1:47 PM Don Klipstein spake thus:
Good advice, no doubt; but unfortunately in my case I have no choice, as I'm working on an existing installation. (This is about a 10-year old set of custom cabinets, with under-cabinet lights illuminating a work area. The lights were installed by the cabinet contractor. Dunno why they chose these particular lights; I also don't like parts of the installation, like where they ran exposed wires (insulated, but not in channel or Romex) between lights.)
Again, sounds like good advice, and I'll take your word as to the accuracy of your list.
But in this case it seems there was a reason they used the lights they did (T5s), since the light fixtures are very low-profile (~2-1/2" wide). Any common light types for fixtures this size? Seems as if T8s would be too big for this application.
The lights are the type with the slip-on plastic diffusers, no switches, hard-wired in place.
There are T5 fluorescents, and some are more common than others.
I do recommend that nyone newly getting fixtures get them from an electrical/lighting supply shop if possible to improve the odds of better quality and of getting them from manufacturers considered more reputable by electricians.
Ballast replacement for a smaller size T5 (13 watts or less) can be a problem big enough to favor replacement of the entire fixture. I would advise considering that a fact of life.
But I would like to add that your earlier article in this thread surely appeared to me to mention a 5 watt T5 lamp - which I have yet to hear of. There are 4 and 6 watt ones, and the 4 watt one has efficiency that is way down as far as fluorescents go - often little improvement over incandescents once ballast losses are considered.
- Don Klipstein ( snipped-for-privacy@misty.com)
On 7/4/2008 2:40 PM Don Klipstein spake thus:
I'm just getting familiar with fluorescent lamp nomenclature. The ballast I need to replace says on it that it's for running 2 lamps: "F8T5/F13T5". The lamps are different lengths. Does this mean the fixture has an 8-watt lamp and a 13-watt one? (The ballast is marked "REF-213-120", which I understand means it can run 2 13-watt lamps.)
It may also be lacking a proper ground. That can keep them from starting as well as the other problems listed.
Thanks to one and all for the help on this. I solved the problem by getting a new electronic ballast.
-- Ray
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