Replace T12 fluorescent bulb with T8 bulbs?

I am switching from T12 shop lights to T8 shoplights. Still have several T12 fixtures. I bought a lot of T8 bulbs but I am out of T12 bulbs.
Can I use T8 bulbs in fixtures that previously used T12 bulbs? Of course, T8 bulbs are 32 watt and T12 are 40W. Will the T8 bulbs kill the ballasts in my remaining T12 fixtures? Will the old T12 ballasts kill my new T8 bulbs?
Thanks for any insight
Walter
www.rationality.net
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T12's are 34 watt. They may work but I wouldn't recommend doing it. Just replace the ballasts with T8 type

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T12's are traditionally 40 watt. The 34 watt one is an "energy saver" version, slightly infamous for "being crankier" including increased starting difficulties and increased vulnerability to cold temperatures.
True 40 watt F40 T12 is still retail-available, and I saw them about a year ago. The hoop to jump through is color rendering index high enough to get an exemption that sounds to me on basis of "specialty lamp". There is a small range of color rendering index (CRI) high enough to meet that requirement, get used in practice, and not significantly compromise light output. Even better, the color distortions of the ones I have in mind and most others in that CRI range are majority in favorable directions unless "warmest" color is chosen - unlike most fluorescent lamps with CRI rated to be less than 82 or in the low 90's.
CRI above 86 typically incurs a severe compromise in light output, by having spectrum including "mid-red to deep-red", which human vision is less sensitive to than to the range from orangish red to mid-blue.
The F40 T12 ones I am talking about now are Philips Ultralume series. I have seen those at Home Depot last year; I expect those are there now.
I recommend the /35U or /835 or similar color code ones (nominally 3500 Kelvin) if you want a halogen-like "whiter shade of warm white". I find the 3000 ones to be "stuffy warm" and to invite expectation of better ability to render red objects such as poinsettia leaves as truly red, as opposed to orangish red. Red objects tend to me to be appear more accurate in color when nominal color temperature of an 82-86 CRI fluorescent lamp is at least 3500 K.
For color like that of traditional "cool white", go for the 4100 version. That's my favorite for economical visual simulation in color and color-rendition effect of "average midday sunlight", along with F32T8 of similar CRI and same nominal color temperature.
However, less-warm color (higher color temperature) has increased requirement of illumination level to "look good", unless the lighting is so dim that higher color temperature gains by being more favorable to stimulating the eye's "rod" photosensors used more in "night vision".
At 4100 K color temperature, my experience is that this only "looks good" when illumination level gets to or above 1,000 lux (about 90 foot-candles).
3500 K appears to me to look good around and above 100 lux (9 foot- candles.) For home lighting dimmer than somewhere around that, moving to even-warmer (lower color temperature) of 3000 or 2700 K is likely best for "nice warm feeling" and avoiding "dreary gray effect". Also, be prepared for a fluorescent including CFL "rated lumen" to be worth as low as 80% of "incandescent lumens" due to temperature sensitivities and aging sensitivities being worse for fluorescents including CFL, combined with fluorescenht having generally lower s/p ratio than incandescent of same color temperature.
--
- Don Klipstein ( snipped-for-privacy@misty.com)

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If the ballast is not a T8 ballast, it will not work. You need a T8 ballast.
My guess is since the fixture already contained T12 lamps, the ballast isn't for a T8. Therefore, you'll need to change the ballast.
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+1...
With most "shop lite" type fixtures the replacement T8 ballast would cost you more than buying a replacement fixture with the proper ballast for T8 lamps already installed in it...
~~ Evan
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news:5563d13c-832b-44a3-ba79- THATS PREPOSTEROUS....WHO DO YOU GET YOUR BALLASTS FROM ? TGITM
Is your "caps" on permanent lock or are you simply an inconsiderate ass?
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On 5/29/2011 6:49 AM, SBH wrote:

Geez - I didn't think you were a new guy here.
Trolls are required to use all caps - it is part of the annoyance. (Actually there are several schools of trolldom. Some use all caps. Some top post with a deleting sig. Some are just idiotic.)
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The "Ghost..." has been told this many times. I skip about 98% of everything he posts noweadays - and rising.
My vote is that the "Ghost" is inconsiderate and effectively either a donkey or a horse's kiester/tookus/bootie.
--
- Don Klipstein ( snipped-for-privacy@misty.com)

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Haven't heard of 'High Ballast Factor' before, but high power factor is a desirable quality in electrical supplies, I'm told.
Joe
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Desirable for whom? Your power company might like you but they won't show their appreciation in your (residential) power bill.
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I have gotten supreme, obviously "commercial grade", ballasts of Sylvania brand, for lamp combos including a pair of F32T8 and F17T8, for $17 each, from an electrical supply shop of the kind that likes its customers to be electricians. About 1.5 years ago. They were Sylvania "Quicktronic" IIRC, and IIRC they were rated to take input AC of either 50 or 60 Hz, along with input voltage in a wide range including 110-120 to 277 (probably plus upward tolerances for 277) or maybe only up to 250. (If I am wrong anywhere here, please chime in.)
In such shops, especially in or near a "union town", be patient. You could easily be in the line behind people being paid bigtime wages to stand in line. Please know what you are ordering, and what you are talking about. Please know what you are talking about including how to do so in "reasonably electrician talk".
--
- Don Klipstein ( snipped-for-privacy@misty.com)

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wrote:

Sure, it will work like this. Install the T8 bulbs. Go to the light switch on the wall. Flip it on. You will see a blinding light so bright that you will be blind for the rest of your life. Within 10 seconds there will be a loud blast. Flames will shoot out of the fixture igniting everything in the room that is flammable. Your house will burn to the ground. Eventually the fire will go out. If you managed to get out the door (since you're blind, you may not find it), you will be saved. If you do not make it out the door, you will burn up, but you still may be saved if you believe in Jesus and confessed your sins lately.
If your life has been dull and boring, this is the way to liven it up.
In Cod we Trust
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Another way to liven up a dull and boring life is to troll in newsgroups.
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replying to , engineerrick wrote: that is dumb and incorrect. i come across t12 fixtures/ballasts frequently in our building previous, lazy people have jammed t8 bulbs into. as if by the grace of god, our building has yet to burn down.
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I have seen 2 T8 bulbs in a fixture that apparently has a T12 ballast. The bulbs have trucked on over a year already.
However, there are predictable effects from the abuse case of running 32W T8 bulbs from a 40W-per-bulb T12 ballast:
* Bulbs may have trouble starting, sometimes intermittent. (T8 bulbs have a higher requirement of ballast output voltage than true 40 watt T12 bulbs have.)
* 32W T8 bulbs powered by a 40W/bulb T12 ballast can easily be overpowered if they start. That is likely to shorten the life of the bulbs, fair chance disproportionately.
* A 32W T8 bulb being powered by a 40W/bulb ballast can have its running being less stable - as in increased vulnerability to flickering effects and increased effects of cold temperatures on stability and ability to start.
There is another matter: Using a bulb of type other than the one or ones on any combination of the ballast label (or nameplate), fixture label, fixture documentation or fixture packaging - is abuse of electrical equipment. Fire insurance companies could give huge major trouble if a fire starts in electrical equipment that is being abused. You could need a good lawyer and good expert witnesses to have only fair-good chance of prevailing if the fire was caused solely by factors other than abuse of electrical equipment.
--
- Don Klipstein ( snipped-for-privacy@misty.com)

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