Got about 60, 3 lamp lights in the walk in coolers and freezers here. They use F48T12/HO 4 foot lamps. They are two ballast fixtures, one for the center lamp and one for the outer two lamps. They are NOT vapor tight fixtures.
Lamp life is not to long, they are three years old and half have been replaced already. There is also a problem with the sockets burning up. They are HO plunger type.
I figure both problems due to moisture but am at loss what to do about it. Maybe some sort of grease on the ends?
My main question boils down to should I expect more problems with these than plain old office troffers and just deal with it?
Btw those lamps and ballasts cost three times more than normal 4 footers.