I just picked up some NOS F40T12VHO 110w lamps. I would like to use them but cannot for the life of me find a proper ballast for them. I was wondering if a ballast that drives F96T12HO 110w lamps would also run these VHOs as they are the same wattage and T12, just half the length. If anybody knows a better option that's still available pls let me know

I just picked up some NOS F40T12VHO 110w lamps. I would like to use them but cannot for the life of me find a proper ballast for them. I was wondering if a ballast that drives F96T12HO 110w lamps would also run these VHOs as they are the same wattage and T12, just half the length. If anybody knows a better option that's still available pls let me know

I might be fine, But I would find a F40T12VHO 110w ballast first. 

Nobody makes a F40T12VHO ballast anymore, I looked all over ebay and can't even find a used one. The Fulham workhorse 7 supposedly runs them but they won't get the full 1500ma.

Just the power level is not telling anything about the ballast compatibility at all...
The most important is the rated arc current and the second the lamp arc voltage.
The different length suggest the arc voltage will be different as well, so if the rated power is the same, the arc current will differ too.

For a short experiment you may try to try it briefly on a magnetic F96T12 ballast and measure the arc voltage. That may tell, what to use as a ballast for this lamp.

A 100W MH ballast will feed it by 1.2A, so pretty close. It will need the ignitor deactivated and a starter (as preheat circuit).

Just tried two of them on an Osram F96T12HO ballast (electronic rapid start), and the ballast must "think" its running F48T12HO (60w) lamps because they're not as intense and kill-a-watt only measures 135w

A 100w M90 ballast would be interesting, is the arc voltage the same though? And what starter to use?

Your result suggests that the current is too low forthe lamp :This lamp is supposed to get higher current, probably by a factor of ~2, to make up for the lower arc voltage - that probably by a factor of ~2 as well

What is the voltage across the lamp end to end, and what is it with the same ballast on a proper F96T12 ? - Measure the voltage after 5 min running time, cold lamps tend to have low arc voltages because there is little Mercury in the discharge

I cant measure the arc voltage because the ballast is HF drive, meter just displays "Err". I have no magnetic F96T12HO ballasts to test. I called Fulham and inquired about running the F40T12-VHO, and they said the closest ballast they make for that lamp is the workhorse 7 as ive read online. However they said the lamps will only see about 92w, and not 110w. 

Try a 40W RS or something similar

The VHO lamp on a RS F40 ballast gives a reading of exactly 100v. A F96T12HO lamp on the exact same ballast doesn't light properly, flickering, striations, and erratic behavior. So it does look like the VHO tube is electrically very different than the F96T12HO.

So it looks like my only option in this case is that Fulham ballast, really wanted to run these at full power though

100V in tyhe 1st seconds or after some warm up ?

If after warm up, 100V is close to the arc voltage of an ordinary F40T12. This means. that you will be able to drive the lamp at full power by paralleling 3 identical (thats important !) F40T12 RS ballasts

But be carefull with ballasts output polarity so that the ballasts really power the lamp and not short each other. Some voltage and current measurement between the outputs of the ballasts will be required before you put it all together

Filament heating - I dont know actually how much heating this lamp takes - It is possible that the filament supply from 1 ballast will suffice, then you only take the arc current wires from the others. I guess experiment with it untill the electrodes glow a very faint red only visible in darkness

Ahh, ok I had never thought of parallel magnetic F40T12 ballasts. In fact, could I also use a 4-lamp electronic instant start T12 ballast and wire three of the outputs to a single lampholder? I posted a pic in my gallery of the lamps in question.

Thatll work. But i wonder what will be the effect of Instant Start and feeding only through 1 pin on each end on the lamp life compared to standard power lamp

A ballast will "see" this lamp the same way as any other 4' T12 (non-energy-saver). That means that a HO ballast will drive it at around 60 watts, and a normal F40T12 ballast will drive it at around 40 watts (assuming full power ballasts here). You need an F48T12/VHO ballast to drive this properly. This is the cheapest one I could find. It is for two lamps.

Oh nice, just going to buy one of those, thanks nicksfan

Back in the day (late 1980s) when I was a kid, I shadowed a very cool guy at the gymnasium my father would go to work out at.   We would change out burned out lights and worn out ballasts, and it is how I became obsessed with lighting at a young age.  They had a bunch of the F40VHOT12s above the 2 indoor pools that we accessed via a mechanical room way up above.  We had to crawl or walk on planks in the ceiling.  The fixtures would hinge open from the top to expose the tubes and ballast, leaving the plastic lens lens in the bottom of the fixture.  I really liked going up there.  The fixtures were cool, and all over the place were broken or EOL tubes that they just scattered around the top of the ceiling, prior to when this guy came to work there.  (he had the decency to take out the ones we replace and throw them out in the Dumpster)  I vividly remember many of those EOL tubes had Orange end caps.  I believe they were Sylvania.  I also remember him changing out a ballast once and the thing was very bulky and heavy vs a regular F40T12 ballast.  Also- most of the fixtures at the Gym had fuses in them too.  Couldn't figure out why.