Thanks for trying, all i found is swimming pool codes 680.22,680.43, and 314.27,and 422.18 and none of which give a requirement. Maybe it is under the archetectual codes.
Is it possible that the issue of height is not an NEC code issue but a building code issue and perhaps this is why it has not yet been found? Unless there is a concern of a potential electrical hazard, should the code address the situation?
I guess I'm starting to think this may not be a code issue at all.
Most ceiling paddle fan installation instructions stipulate that the fan blades are not to be less than 7 feet from the finished floor.
If you need an NEC reference, 110.3(B) would be the one.
An 8 foot ceiling in my opinion is obsolete. People are on average taller than they were 60 years ago.
For that matter, my shoe size is "obsolete" and I often have to buy oversize shoes to get shoes that are wide enough for my feet. I was told by shoe sales lady that some older men now have to buy children's shoes because of trends in foot size!