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Fluorescent Bulbs: T12 in a T8 Fixture? Login/Join 
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Came into some T12 bulbs, but the fixtures we have are T8.

Any issue with using T12 bulbs in T8 fixtures?




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Posts: 8236 | Location: Spring, TX | Registered: July 11, 2011Reply With QuoteReport This Post
Ammoholic
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They should not work, but sometimes do. Also T8 sockets are generally shorter so the lamps may not work. The lamps are pretty much useless nowadays.



Jesse

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Posts: 17161 | Location: Loudoun County, Virginia | Registered: December 27, 2014Reply With QuoteReport This Post
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The pins seem the same & they're both 48" bulbs.
The T12 are just a larger diameter.




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Posts: 8236 | Location: Spring, TX | Registered: July 11, 2011Reply With QuoteReport This Post
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They are the same length, and will work. However once I installed some T8's into a custom lighting cabinet that had T12's.

The ballast overheated and almost caused a fire.


-c1steve
 
Posts: 3071 | Location: West coast | Registered: March 31, 2012Reply With QuoteReport This Post
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Not a good idea

Still a number of T12 fixtures around. If I were local to you, I would offer to buy new T8 and trade you for some T12 lamps. Maybe someone there needs them and would make you an offer.
 
Posts: 1015 | Location: Moved to N.W. MT. | Registered: April 26, 2009Reply With QuoteReport This Post
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I believe the answer depends on your ballast. Some have a wider range of applicable bulbs than others.

When I was still doing electrical at work, we could never get the custodial stuff to understand that there were right and wrong bulbs, and just because it fit didn't make it right. I actually started writing inside the lights with magic marker... "bombilla flaco" and "bomilla gordo" but even that didn't help. When correcting one woman I was told.. "No, I like these ones better." lmao Big Grin

Anyway.. I seem to recall the life of the bulbs being shorter, but I can't recall which way (T8s in 12 fixtures or vice versa) was worse. Over driving them or under driving them. I don't recall changing any more ballast that normal, we certainly had no fires and we had thousands of ballasts.


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Posts: 17856 | Location: 18th & Fairfax  | Registered: May 17, 2003Reply With QuoteReport This Post
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I have found T12 in a T8 fixture. And vice versa. Both working fine.

I have also found one T12 and one T8 in the same 2 lamp fixture. There are real stupid lamp changers out there.

At my gun club we have switched a few T12 LB240 over to one end LED direct wired. I fear those stupid lamp changers more now.



SIGnature
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Posts: 5343 | Location: Duckburg, OR | Registered: September 01, 2001Reply With QuoteReport This Post
Just because you can,
doesn't mean you should
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I don't know how many bulbs you have but LED's have become really cheap if you buy them 25 at a time online. You can get the type that don't use a ballast and they pay for themselves in 6 months or less in energy savings. You use T8 or T 12 fixtures.
My shop where they run about 8 hours a day was a 3 month payoff with better, brighter light.
 
Posts: 6133 | Location: NE GA | Registered: August 22, 2002Reply With QuoteReport This Post
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Well, got lucky. Pulled the cover off the fixture in our laundry room & it had 2 T12 in it.
One had burned out, so swapped in one of the new ones.

Master closet & garage are all T8.
The LED T8 we got say electronic ballast only, would that be marked on the ballast?




The Enemy's gate is down.
 
Posts: 8236 | Location: Spring, TX | Registered: July 11, 2011Reply With QuoteReport This Post
Just because you can,
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If you buy LED's, get the ones for no ballast. The wiring is really simple and you remove the ballast (a potential fire issue) and a cause of failure later.
The savings in energy is substantial.
 
Posts: 6133 | Location: NE GA | Registered: August 22, 2002Reply With QuoteReport This Post
Ammoholic
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quote:
Originally posted by P250UA5:
Well, got lucky. Pulled the cover off the fixture in our laundry room & it had 2 T12 in it.
One had burned out, so swapped in one of the new ones.

Master closet & garage are all T8.
The LED T8 we got say electronic ballast only, would that be marked on the ballast?


98% or greater of T8 are electronic, I've only seen a handful of magnetic T8 ever, and I've seen thousands of fixtures. You would have take the cover off to tell. Magnetic ones are about 3" wide, electronic are half as wide, and will likely say electronic on the ballast.



Jesse

Sic Semper Tyrannis
 
Posts: 17161 | Location: Loudoun County, Virginia | Registered: December 27, 2014Reply With QuoteReport This Post
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