Ted White has sent the following information about UV box usage. I thought it might be useful information. Please email me with your comments. This page is open to addenda.:
"In a former life I used UV-C narrow band 254 nm wavelength tubes for water treatment. The glass the tubes were made of would solarize after about 8000 hours of use and prevent the UV light from escaping the tube. Since this was a germicidal application were routinely replaced the tubes well before this time limit. These lamps would literally cook the cornea of the eye much in the same manner as a welder's "flash" damages the eye.
Not all UV-B lamps are created equal. The ones you can pick up for reptiles in pet stores do not produce the same spectrum as the lamps used for tanning or treatment of skin disorders. The bandwidth of the spectrum can vary quite a lot which means that the particular wavelength's amplitude which is effective in curing oil varnish can vary.
I have used UV-A lamps for years and they do work. UV-A and UV-B both put out waverlengths which can cure oil but in differing amounts. So the real question is how quickly do you need a cure? Like Yanbing I find UV-A cures my finishes in about 24 hours. UV-B might be a little faster but in my shop and work cycle it hardly matters.
And, having had to work with the really dangerous UV-C, I appreciate the fact that a dumb mistake, like opening the cabinet with the lamps on, is less likely to cause damage to my eyes. My dad was a welder and had to have cataract surgery earlier than normal probably because people were a little more cavalier about UV damage in the old days."