Bulb longevity: power compact, NO, VHO.

[Rikko]

I guess technically *all* fluorescent bulbs are UV shielded. If the bulb is firing and there's no light coming out, that means there's no coating inside and it's pure UV coming off it. Er. Don't look at it. Just run away.

Obviously the NO T12 will outlive the VHO (unless perhaps if you're lucky and keep the VHO very well cooled), and I'd except it would outlast the PC as well. PC bulbs are one type that I regard as failing physically rather than just sputtering out. I guess they're just a little more sensitive. Lifespan? PC probably a couple years on average. VHO might stick it out for five years or so. That NO will probably do well by you for a good 20 years.

I don't like buying expensive bulbs all the time, so I tend to only replace them when I either notice a difference in their light output (compared to an identical one), they completely die, or I see too much corrosion on the metal areas for comfort.