Replacing fluorescent bulb

Light went out in the bathroom. It's a 48" 25W T12 GE fluorescent bulb.
I can get one online, but I'd rather rush it and buy one in a brick and mortar store. Problem is that they only have 32W and 40W. Does that matter?
TIA,
S
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It *could* matter for 2 reasons:
1 - The fixture might not be rated for the higher wattage. There should be a label on the fixture stating the maximum wattage to use.
2 - Assuming the fixture can handle one of the higher wattage bulbs, the question is - can you? If you're used to 25W and are comfortable with the lighting effect, then 32W or 40W might be too bright, especially in a bathroom in the middle of the night.
Easy answer: If the fixture can handle the high wattage, try one and see. The borg will take it back if you don't like it.
P.S. - I use incandescents in the bathrooms so I can use dimmers.
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wrote:

Thanks for responding.

Would that it were so. It's an old house we're renting. No label.
Aside from the point you make, changing the wattage won't mess up or otherwise be incompatible with the "ballast" thing-ee?

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-- Aside from the point you make, changing the wattage won't mess up or otherwise be incompatible with the "ballast" thing-ee?
Uh, what point did you think I was making?
When I said "The fixture might not be rated for the higher wattage" I meant the wattage might "mess up or otherwise be incompatible with the "ballast" thing-ee"
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wrote:

OK. One of the fluorescent light FAQs on the web implied that one might also worry about the rating of the circuit powering all of it. which is what I assumed you were referring to.
Cheers.
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-- "One of the fluorescent light FAQs on the web implied that one might also worry about the rating of the circuit powering all of it."
Someone correct me if I'm wrong...like I even have to ask.
I can not imagine a circumstance where one would need to be concerned about the "rating of the circuit powering all of it" when considering replacing a 25W fluorescent tube with a 32W fluorescent tube.
Please post a link to the FAQ...I'm always willing to learn something.
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wrote:

My bad. Went back and looked at the FAQ and indeed it was in the context of the ballast not matching.
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in part:

It is normally a "Bad Idea" to use bulbs of wattage that the ballast is not specifically rated for. In some cases, this may even be a fire hazard.
However, if a 40 watt 4-foot bulb appears to run OK on a ballast for same size 25 watt bulb/"lamp", you won't overheat anything, at least not worse than anything that would happen with a 25-watter. The 40-watter may have shortened life from the filaments running too cool to work properly as electrodes.
One thing to check: Open the fixture and read the ballast label. Not only see what "lamps" (bulbs) the ballast is rated for, but also see if the ballast is one of those el-cheapo stool specimen shop light ones that require the fixture to be suspended in mid-air for the ballast to reliably not overheat.
Also see if the ballast is for running more lamps than the fixture takes - this requires replacing the ballast, otherwise the ballast can overheat. Most ballasts for 25 watt lamps are for 2 of them.
Maybe you might find the ballast was for 40/34/30, 40/34 watt lamps or 40 watt lamps only. In that case the ballast could have overheated on the 25-watter.
Ballasts for 2 4-footers usually have "Class P thermal protection" - a "bulb" with a bimetal switch. If the ballast overheats, it cycles on/off every several minutes or a couple to a few times an hour. However, I suspect the bimetal switch could "get stuck" if this goes on too long without the situation being fixed. I have also seen this switch appear to me to not be sensitive enough: My experience includes a dual-40-watt rapid start ballast with a shorted output series capacitor. That makes the ballast run much hotter than it should, but I did not see that thermal switch cut in. The main visible symptom was that the ballast "eats bulbs" (life only a couple thousand hours). If you have a clamp-on AC ammeter and put it around one ballast input lead, you will see obviously abnormally high current if that capacitor is shorted - not only does the fixture take more watts, but also the power factor goes down. But I digressed from the point of that thermal switch not always being what I think it should be.
- Don Klipstein ( snipped-for-privacy@misty.com)
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On Fri, 12 Oct 2007 13:46:41 -0400, sinister wrote:

Got a lighting store around? Make some calls.
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sinister wrote:

What is the actual label printed on the bulb? Is something like F48T12CW?
TDD
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GE Utility Shoplite F48"/25W/UTSL 25W USA Hg

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on 10/12/2007 3:47 PM sinister said the following:

That's a utility shoplight! That's made for a building or warehouse, so that people don't trip over stuff on the floor. Wouldn't you want a cool white in the bathroom? A Cool white lasts almost twice as long as a shoplight. 2000 hrs. on a CW vs. 1200 hrs. on a SL. No wonder you don't get a close shave. :-)
--

Bill
In Hamptonburgh, NY
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Like I said, it's an old house that I'm renting. Plumber says there's all sorts of crazy mismatched sh*t in here.

Tell that to my wife; it's her BR actually. :-)
I couldn't really find a 48" 25W T12 online, so the guy at the light store gave me a 48" T8 32W. Seems to work OK, though it flickers at a low rate somewhat.
Cheers.

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in part:

The low rate flicker usually fixes itself after a few to a dozen so operating hours followed by a couple on/off cycles. If not, then you have a bulb/ballast mismatch causing this and you need to have the bulb match the ballast (and in this case I would change the ballast and not the bulb - thankfully "big box" home centers tend to have good ballasts for F32T8!).
- Don Klipstein ( snipped-for-privacy@misty.com)
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No, warehouses and commercial buildings don't use the garbage known as 25 watt 4-foot fluorescent. The 25 watt rubbish is often known as "residential grade" to those who know some things about this trade. The 25 watt trash goes into home basements and garages, and sometimes contributes to ill feelings to fluorescents.

No, I would want something warmer, though whiter than incandescent. There is such a thing - 3500 K. For old technology lower color rendering index 40 watt 4-footer, this is called "white" and has color code /W. One of the "Big 3" made a higher-color-rendering-index light-output-compromised version that I think of as the "Deluixe", though it was called "Merchandising White", with color code MWX. A good one with color rendering index 85 and color distortions mostly being towards "more vivid" and full uncompromised light output is Philips Ultralume 3500.

Multiply by 10 - but only when averaging near or over 3 hours per start and with a good quality ballast that is rated for the bulb/"lamp" being used (which I think is less likely with a cheap "residential grade" "shop light"). Keep in mind how long overhead fluorescent bulbs last in offices and classrooms!
- Don Klipstein ( snipped-for-privacy@misty.com)
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Those 25w tubes are actually just 40w tubes with electrodes optimized for lower power. They will run on a 40w ballast, but with shortened life.
It's likely this fixture has a cheap uncorrected residential 40w ballast in it, and some previous owner/tenant that didn't know better put the 25w tube in there. Your best bet would be the 40w tube then. I would avoid those 25w tubes at all costs unless you have a 25w shoplite that specifically says it can use them. They're only really designed for low power use in those 25w shoplites.
Yes, I have seen 32w tubes in these types of ballasts with little ill effect. These residential ballasts do actually underpower even a 40w tube somewhat, and a 32w T8 tube have a higher operating voltage and will be only slightly overpowered.
When all set and done, I would not chance a 34w tube in any residential ballast unless it specifically says it can use them. That's because 34w tubes have a different gas misture and cheap uncorrected residental ballasts will severly overheat.
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I suspect a fair chance the ballast is an el-cheapo "residential grade" one with fairly low efficiency.
What I would do: Get a ballast for a 32 watt T8 bulb. Then get a T8 3500K bulb of the "upper" color rendering index (85-86), and of the "Big 3" brands these are:
Philips F32T8/TL835, F32T8/ADV835 Sylvania FO32/D835 GE F32T8/SPX35
The lower color rendering index ones have 7 in place of 8, or with GE SP in place of SPX.
3500K is a "semi warm white", which I consider halogenlike though it is a little whiter and less yellow. I find it very pleasant, especially in brighter areas such as a bathroom with this much light.
If you want a warmer color, these also come in 3000 K. Change 35 to 30 in the color code.
Where to get: Electric/lighting supply shops. Big box home centers in my experience only carry the lower color rendering index grade (color rendering index in the upper 70's), though I often see both 3500K and 4100K (cool white color) ones.
The usual ballasts for F32T8 lamps are high quality high efficiency electronic ballasts.
- Don Klipstein ( snipped-for-privacy@misty.com)
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