T8 v T12 fixtures

[Eric]

This might be a sfq, but here goes.

I have two shoplights with T12s.  I noticed two bulbs on one light were out.  I seem to remember that two bulbs might go out if only one burns out (like the xmas lights I hate).  Anyway, I couldn't get to the store so I put a T8 aquaglo bulb in.  I was sursprised it fit just fine.

So the T-8 is now on, and the other one came on dimly and went out.  I don't have another T-8 to test, but would the light drive two T-8s?  Is there a reason not to do this?  Both bulbs are 40w.

Bit confused and wondering 

[BigDaddy]

First off Eric, there are no sfq's on this website 

A T12 fixture can fire T8 bulbs if the ballast is a rapid start.  Obviously yours is, as it did fire the one T8.  You should be able to put a second T8 in there no problem

[Saltcreep]

This might be a sfq, but here goes.

I have two shoplights with T12s.  I noticed two bulbs on one light were out.  I seem to remember that two bulbs might go out if only one burns out (like the xmas lights I hate).  Anyway, I couldn't get to the store so I put a T8 aquaglo bulb in.  I was sursprised it fit just fine.

So the T-8 is now on, and the other one came on dimly and went out.  I don't have another T-8 to test, but would the light drive two T-8s?  Is there a reason not to do this?  Both bulbs are 40w.

Bit confused and wondering 

I had the same question myself. Luckily, I'm well acquainted with a third year apprentice electrician. When I asked him about it his answer was simple. It will work but, how much do you value your house? Definite fire hazard in his opinion. He asked me back, 'if you could safely run T8s off a T12 ballast, why would anyone replace their fixtures'? He also mentioned that the new T8 ballasts run cooler, light more quickly, are more reliable in cooler temperatures, don't flicker, last longer and produce more useable light while consuming less energy. Also, the newer ballasts don't contain PCBs while older T12s easily could. I had over 20 T12 double-tube fixtures in my basement. All the ballasts have now been converted to T8s. One last thing; T12 ballasts running T8s will shorten the tube life significantly.

[veron]

SALTCREEP. is very correct. just had  NEDCO LIGHTING and HYDRO ONE speakers at our meeting.
magnetic ballasts and T12 lighting will be/are a thing of the past.
only thing I disaggree with is the fire scare? the lamp will just burn out faster, like overdriven a lamp with an ICECAP VHO ballast.

[Saltcreep]

SALTCREEP. is very correct. just had  NEDCO LIGHTING and HYDRO ONE speakers at our meeting.
magnetic ballasts and T12 lighting will be/are a thing of the past.
only thing I disaggree with is the fire scare? the lamp will just burn out faster, like overdriven a lamp with an ICECAP VHO ballast.

You could be correct about the risk of fire but, with fire, I take no chances. And you are certainly correct about T12s being replaced. A few months ago I tried to buy a new T12 shoplight fixture at HD. There were none and the very helpful salesperson told me they would not be getting any more in; only T8s. That turned out to be slightly incorrect as more were in stock shortly after. However, I suspect that the lighting manufacturers have had to slow down a bit simply because of the sheer numbers of fixtures to be replaced over time. It would be in the hundreds of millions or even billions. It is evident in the electrical trade too; my apprentice friend says replacing T12 ballasts with new T8s has become a huge part of his regular duties and there are more and more everyday.

My simple advice would be to scrap the old T12s as soon as you can afford to convert. Even the cost of T8 tubes has begun to come down and you can now buy contractor packs at HD.

[BigDaddy]

I too do not understand how there is a fire risk.  The T8 bulbs are drawing LESS power than the T12 bulbs.  If it is not a fire risk to drive 40W of power, I can not see how it suddenly becomes a fire risk driving 30W to 36W (depending on the T8).  I can't see a ballast running below its operational specs being a fire hazard.

As far as bulb life goes, most aquarists replace their bulbs within a year or two anyway.  This is far sooner than the rated 10,000+ hrs (12hrs a day X 365 days = 4380hrs)