# F34 T12 vs F40 T12 bulbs



## Ultrarunner2017 (Oct 1, 2008)

Hi;
I recently bought two new 4' tubes of the T12 variety from Home Depot.
The new tubes are F34 rather than F40, but that is all they had, so I figured as long as it's not higher than the fixture's rating (they are rated for 40 watt), everything will work just fine.

But, when I installed the two new bulbs into the fixture, they just sat there and glowed on the ends. I quickly shut it off and removed the bulbs.
Then I started going around to other fixtures and trying the new bulbs.
I found that one fixture works fine with the 34 watt bulbs, but the two "Diamond Plate" work lights which have electronic ballasts will not work with these bulbs.

So I don't know what to do. I don't have any more 40W bulbs to swap out, and I don't think I am going to be able to buy them easily anymore, since it appears that the 34 watt has replaced the 40 watt.
Should I ditch the Diamond Plate lights and get something else?

Note: I also notice that one of the Diamond Plate fixtures acts really strange. If I remove just one bulb, the other goes out too. But in the other Diamond Plate (same model) fixture, removing one bulb leaves the other lit.
I did not modify the wiring of the fixtures, so they should both be the same.

Honestly, i would like to replace the fluorescents with LED's, but they are way too expensive right now.

Thanks for your help.

FW


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## Missouri Bound (Apr 9, 2011)

Read the ballast. Matching the correct lamps with ballasts is necessary for proper performance and life of lamp and ballast. Are you sure you installed the bulbs properly? I know that question may seem like an insult, but the bi-pin bulbs need to be seated properly to work correctly. Also t-8 and t-12 bulbs are not interchangeable.


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## kbsparky (Sep 11, 2008)

Lowe's has 40 watt T-12 fluorescents.

About $15 for a 10-pak.

They are much brighter (3000 lumens) than those 34 watt pieces of junk (2650 lumens).


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## Ultrarunner2017 (Oct 1, 2008)

kbsparky said:


> Lowe's has 40 watt T-12 fluorescents.
> 
> About $15 for a 10-pak.
> 
> They are much brighter (3000 lumens) than those 34 watt pieces of junk (2650 lumens).


Thanks KB;
They just opened a Lowes near me. I'll run over there today or tomorrow.
As for the two 34W I bought, I guess I'll keep them in the fixture they work in, until they start to wear out, then go back to the 40W.

FW


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## AllanJ (Nov 24, 2007)

In fluorescent (also mercury and sodum and metal-halide) fixtures too high a wattage lamp can damage the ballast; too low a wattage lamp can burn out quickly.

Except for series circuits (pretty much limited to Christmas lights) for incandescent lamps (incl. tungsten-halogen and tungsten-xenon) you can freely substitute a lower wattage lamp.


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## kbsparky (Sep 11, 2008)

AllanJ said:


> In fluorescent (also mercury and sodum and metal-halide) fixtures too high a wattage lamp can damage the ballast; too low a wattage lamp can burn out quickly....


The OP did state that the fixtures in question were rated for 40 watt bulbs.

KE2KB, if you are still reading this thread, be advised that those 34 watt lamps do not work well in cold ambient temperatures. They definitely will not get very bright at all.


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## Ultrarunner2017 (Oct 1, 2008)

kbsparky said:


> The OP did state that the fixtures in question were rated for 40 watt bulbs.
> 
> KE2KB, if you are still reading this thread, be advised that those 34 watt lamps do not work well in cold ambient temperatures. They definitely will not get very bright at all.


Ah ha!
I have been having problems even with the 40W bulbs in the electronic ballast "Diamond Plate" shop fixtures. They don't work very well at all when the basement is cold.
So, if that's happening with the 40W bulbs, I think I should be shopping for better fixtures.
Perhaps LED, but that might not fit my budget at the moment.

Still, I will pick up a pack of the 40W tubes.

Thanks

FW


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## Missouri Bound (Apr 9, 2011)

If you want better flourescents...go to T8 technology. Better lamps available, brighter and the electronic ballasts are inherently cold weather compatable.


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## ddawg16 (Aug 15, 2011)

Missouri Bound said:


> If you want better flourescents...go to T8 technology. Better lamps available, brighter and the electronic ballasts are inherently cold weather compatable.


Without a doubt.....

I also like the T5 bulbs.....


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