Such a requirement is a design decision, not a code one. Strictly speaking, the NEC doesn't mandate such things; it only allows other rules to be waived if such is present.
Medical facilities have all manner of 'special' needs these days. Not only is there the desire not to ignite anesthetic vapors, there are back-up power and ground fault protection decisions to be made. Then there's that whole 'equipotential plane' thing ....
In short, this is where the engineer or architect has to actually do some work, and not foist it all off on the trades to sort out.
