jtr1962, I was thinking along those lines, thank you for confirming my suspicions, and the detailed explanation

winny, you probably don't have the exact same tubes available in Europe then, my numbers above are for standard 48" GE ones here.
Of course, as jtr1962's pointed out, you're not missing anything
Well, as indifferent as I've been to electronic ballasted linear T8 tubes...mebbe it's time to join this century & try some out...