Hello to everyone i have some lamp with T8 electronic ballast and i don't know could i use them on electronic ballast or not.What you think what is better if i have T12 bulbs ?

Pozdrav svima imam jednu lampu sa T8 elektronskom prigušnicom i ne znam da li mogu da ih korisitm na elektronskoj prigušnici.Šta mislite šta je bolje ako imam T12 fluo cevi ?

Qs I understood, you are talking about running an F40T12 on a F36T8 ballast, or F20 on an F18 ballast. In these cases the ballast will be perfectly fine, but in case the ballast is programmed start, the lamp may cold starting and so wear off faster than intended.
The cause is the way lower ignition voltage of T12's, while the ballasts during preheating phase tend to expose the lamp to a voltage which is assumed to be below the ignition threshold of the intended lamp, but that is not the case for the T12's.

Qs I understood, you are talking about running an F40T12 on a F36T8 ballast, or F20 on an F18 ballast. In these cases the ballast will be perfectly fine, but in case the ballast is programmed start, the lamp may cold starting and so wear off faster than intended.
The cause is the way lower ignition voltage of T12's, while the ballasts during preheating phase tend to expose the lamp to a voltage which is assumed to be below the ignition threshold of the intended lamp, but that is not the case for the T12's.

Thanks for info.

T12's + lower ignition voltage... could this be the reason why most of my F15T12's start almost instantly
on each of my HPF Trigger Start ballasts? Most of my F15T8 lamps start up slower than my F15T12's, although
still quick to start.

T12's + lower ignition voltage... could this be the reason why most of my F15T12's start almost instantly
on each of my HPF Trigger Start ballasts? Most of my F15T8 lamps start up slower than my F15T12's, although
still quick to start.

Both of your lamps have argon, so both have low ignition voltage. These are only the European Krypton T8 that have higher ignition voltage and won't work on American systems, except preheat (Provided the OCV is 230V and above).

Even when both use argon (and generally if they differ only in the tube diameter), a thicker tube is always easier (so suffices with lower voltage orless preheating) to ignite.
In your case it means the F15T8 needs the electrodes to warmup really to significant emission, the T12 ignite when the electrodes are still way colder. That means faster, but with more wear...

That's one thing I forgot to mention... the electrode filaments in all of my previous USA GE F15T8's, seem completely
different compared to the electrode filaments in all of my Sylvania F15T12's. My oldest GE F15T12 has the longest start up
flicker out of all of my 15 watt lamps in my collection... and the filament within that one seems thinner and very curly
compared to all of my other T12's and T8's. The T8's also had curly filaments as well. Does filament structure play a role
in start up?

Even when both use argon (and generally if they differ only in the tube diameter), a thicker tube is always easier (so suffices with lower voltage orless preheating) to ignite.
In your case it means the F15T8 needs the electrodes to warmup really to significant emission, the T12 ignite when the electrodes are still way colder. That means faster, but with more wear...

Yes that is true.I saw some T12 bulbs on electronic ballast died earlier than preheat ones.

Does filament structure play a role in start up?

For rapid start...yep as a mater of a fact it does, The faster the filament warms up, the faster the lamp will start up.
A thicker more robust filament (or a longer one) in general will take longer to warm up.

Instant start ofcourse it doesn't matter, since that rams high voltage through the lamp with un-heated filaments.

@xmaslightguy... ohhh ok lol that makes sense. Because my older GE F15T12 does contain longer electrode filaments than all of the
rest as well. My Sylvania ones, including my F15T8's, all contain those shorter, straightened electrode filaments though, and all
of those seem thicker. More start up flicker with the Sylvania F15T8's, but not as much as the GE F15T8's. And almost no start up
flicker whatsoever with the Sylvania F15T12's.
I should add -- almost all of my Sylvania F15T8's ended up with broken filaments over time after being used on my HPF Trigger
Start ballasts. My guess is the high filament heating caused breakage

@xmaslightguy... ohhh ok lol that makes sense. Because my older GE F15T12 does contain longer electrode filaments than all of the
rest as well. My Sylvania ones, including my F15T8's, all contain those shorter, straightened electrode filaments though, and all
of those seem thicker. More start up flicker with the Sylvania F15T8's, but not as much as the GE F15T8's. And almost no start up
flicker whatsoever with the Sylvania F15T12's.
I should add -- almost all of my Sylvania F15T8's ended up with broken filaments over time after being used on my HPF Trigger
Start ballasts. My guess is the high filament heating caused breakage

Thanks to all memebers for sharing advices.