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scottyja 11-02-2008 02:28 PM

T12 bulb in a T8 fixture
I have a basic question I'm hoping someone can give a quick response on. I just replaced some 48" fluorescent bulbs in my garage and master closet. The previous bulbs were 32 watt T8 bulbs. The guy at the hardware store said the thicker T12 40 watt bulbs would work fine. Since they were $6 cheaper a bulb, I picked up the T12 40 watt bulbs. When replacing them, I noticed a sticker saying "Use only T8 bulbs". I went ahead and put in the T12's and turned them on, and they seem to work OK, just a different color than the others in the room, which isn't a big deal.

My question is why they would say use only T8's? Is it a bulb-life or efficiency issue, or do I run the risk of burning the house down? Right now they've been removed, and I'm wondering if it's necessary to go get the more expensive T8 tubes.

nap 11-02-2008 03:49 PM

life expectancy of the lamp and the ballast will be compromised. The power needs are different for the 2 different size lamps and the higher wattage required by the larger lamps will tax the ballast and cause premature failure.

$6 less? what kind of lamps are you buying? Neither lamp should be over a couple bucks each unless you are using HO or VHO (which requires a different ballast so dont do that unless the ballast is designed for them)

and I believe you meant T 8 and T 12, right?

with a basic lamp, you will have an option of light color. A 3000Knumber will be kind of pinkish. Then you go to a 4100K which is fairly white and then on up. The next step up I think is a 5000K. They start to get expensive at the 5000K and up color.

scottyja 11-02-2008 03:55 PM

I was a bit surprised too. It's a smaller local hardware store, but the only 48" T8 bulbs were $7.50, where a 2 pack of T12's was $3. Maybe I'll take them back and see what I can find at the big box stores.

KE2KB 11-02-2008 04:44 PM

I suspect he's selling T8 plant and aquarium bulbs, which are a lot more expensive.

Speedy Petey 11-02-2008 05:06 PM

The color temperature of the lamp has a HUGE bearing on the price.
I get F32-T8 741's for under $2. The same lamp in a "true light" is about $6 my cost.

You can't simply say I get T8's or T12's for $X each.

nap 11-02-2008 06:23 PM


Originally Posted by Speedy Petey (Post 179974)

You can't simply say I get T8's or T12's for $X each.

Yes I can. I can say anything I want. The US Constitution says I can.

Just kidding.

I understand your point petey but I am speaking of generic T8's and 12's with a color temp of 4100 or less. As I stated in my first post, they do get pricier as the color gets whiter and yes, there are other differences that can alter the price but just speaking of generic lamps.

I had to find some 6800K 98 CRI lamps before. I never got to see the price. I was kind of afraid to see it actually.

Speedy Petey 11-02-2008 06:50 PM


Originally Posted by nap (Post 179994)
Yes I can. I can say anything I want. The US Constitution says I can.

OK, you got me there. :laughing: :thumbsup:

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