It would be incorrect to lump all tortoises into one catagory and say they all need the same amounts of UVB. In nature Redfoot tortoises are rainforest animals, and do not bask in the sun! They tend to hide from it in damp undergrowth. Especially in their hatchling and adolescent stages. They are being raised quite successfully in Tennessee and other places with absolutely no UVB at all!
Check it out:
www.turtletary.com/redfootcare.htm

Beth in AZ
(btw, I took the course from TortoiseTrust, highly recommended!)