Can T8's work with a T12 ballast?

[RTcat]

So last week i buy my T8 fixtures and T8 bulbs for my new shop from HD. Lithonia brand on the box. Most of the fixtures are 8' with four 4' bulbs. I needed a couple of 4' fixtures also. Install and wire everything and all is good. Realized I'm one 4' fixture short.

Today I go to HD to pic up one more 4' fixture...yikes, price as gone up $7 since last week...WTF...that seems odd??? So I look a little closer. Two piles of 4' fixtures. One box labeled T12 ($19) and the other T8($26). Rut Roh, I bought and installed the T12's...but used T8 bulbs???? But why are my 4' fixtures working in the shop????

So I open the T12 box and look at the ballast. It has a chart on the ballast and it lists T12's at 40 watts and T8's at 32 watts (along with some other combinations).

Is it possible that while the box says T12, this fixture (ballast) can run either T8's or T12's bulbs?

 

[rlitman]

The tombstones are the same. If your ballest lists T8 bulbs, you're good to go.

 

[Falcon67]

You either got lucky or there is some serious bait-n-switch going on in fixture pricing.

 

[pattenp]

The tombstones are the same. If your ballest lists T8 bulbs, you're good to go.

Not totally true on the tombstones. A T12 tombstone is taller than a tombstone made for T8.

 

[wssix99]

Is it possible that while the box says T12, this fixture (ballast) can run either T8's or T12's bulbs?

Sure. That's all dependent on the ballast inside. If you compare the ballasts between your two fixtures, they may even be the same.

Today I go to HD to pic up one more 4' fixture...yikes, price as gone up $7 since last week...WTF...that seems odd??? So I look a little closer. Two piles of 4' fixtures. One box labeled T12 ($19) and the other T8($26).

This is really common in big box retailers. The process for price changes is enormous when you consider that HD has to manage the change across all of their hundreds of stores, change all the shelf labels, update their IT systems, etc. So, they pace the changes out, even within the same category. There is a method to how they choose the order of items/SKUs to change - but only they would know what that is.

My expectation is that if you go back in 2 weeks, all of the other prices on the aisle will also have gone up. If not, this case could be one of supply vs. demand. T12 fixtures are more common and I expect that they sell many more of them vs. the T8's.

 

[Norcal]

Not totally true on the tombstones. A T12 tombstone is taller than a tombstone made for T8.

Not true they are the same, they are taller on VHO, 1500 ma fixures, then HO, 800 ma fixtures.

To the OP,
T8 lamps do "work" on T12 ballasts but expect short lamp life......

 

[pattenp]

Not true they are the same, they are taller on VHO, 1500 ma fixures, then HO, 800 ma fixtures.

To the OP,
T8 lamps do "work" on T12 ballasts but expect short lamp life......

I have both standard T12 and T8 fixtures. All I can say is in the fixtures I have the tombstones are about 1.5" tall in the T12 and about 1" tall in the T8. I tried to see if I could get a T12 tube to fit in the T8 fixture and the bulb is too fat.

 

[darcyh]

I have looked and looked and never found a ballast that says it will operate both a T12 or T8. What brand of ballast is it?

Dave

 

[darcyh]

Not true they are the same, they are taller on VHO, 1500 ma fixures, then HO, 800 ma fixtures.

To the OP,
T8 lamps do "work" on T12 ballasts but expect short lamp life......

I don't doubt you, but can you explain why short lamp life should be expected.

Thanks,
Dave

 

[Charles (in GA)]

I have looked and looked and never found a ballast that says it will operate both a T12 or T8. What brand of ballast is it?

Dave

Go to Home Depot and look at the replacement GE ballast they sell. A good many of them specify both T8 and T12 lamps. As long as you are using what they specify (length, wattage, etc) you are OK. I think they are able to do this with the new electronic ballast, something you would never see with the old transformer ballast.

Charles

 

[RTcat]

Thanks for all the input...looks like I'll be ok. Here's some pics to help clarify...

Link to the actual ballast


http://keystoneballast.com/store/products/electronic-fluorescent/compact-fluorescent/kteb-240-1-tp.html

You may have to dbl click the pictures to get them to full size. Then, hover over the picture with your mouse and click when you see the "+" sign.

The last picture shows the fixture in question on the bottom and the 8' T8 next to it. As you can see the 8' T8 has the bulbs closer to the fixture than the 4' we've been discussing that can handle both T8's and T12's

 

[Gregishome]

I do not have links to post at this time but like incandescent bulbs, the T12's are on the way out. They do not comply to the EPA's warm and fuzzy list for being energy nibblers. ...

The old T12 electromagnetic ballasts have to go eventually, and all you will see are the more energy usage friendly T8's with the electronic ballasts.....

All new commercial/industrial fixture installs now are T8's with electronic ballasts. They seem to be a little bit less bright than the old T12's overall, but they do save on power consumption... jmo

 

[pattenp]

I thought some of the T12's were exempt, such as T12HO. The lighting industry is already making T12 electronic ballast that replace the old magnetic ones that have been banned.

I also thought that Sylvania has come out with a T12 tube that meets the requirements.

 

[PatJ800]

My personal experience is that a rapid start magnetic T-12 ballast will light some (most?) 32W T-8 lamps with very short lamp life but they will not light a 28W T-8 and an electronic T-12 ballast won't seem to light either 28w or 32w T-8. Just my experience. Honestly I am not sure why because on paper any T-12 ballast should light the T-8 just fine in theory.

The reason for the short lamp life I assume is that the T-12 ballasts allow more current to flow through a lamp than a T-8 ballast will and a fluorescent ballast's main purpose in life is to limit current flow through a lamp.

Also I have retrofitted a zillion ba-jillion T-12 lamps to T-8 with new ballasts and I have never noticed a difference in tombstone height as a general rule. There are subtle differences by manufacturer but Lithonia for example is the same for T-8 and T-12. There is an electrical difference in rapid start and instant start though. Of course this is all for the G13 base - the recessed contact base is different.