yaktx, something to keep in mind is that Table 310.15(B)(6) is not an conductor ampacity table at all. It is not at all the same as 310.16 etc.
It is simply a section of code that allows ignoring the usually conductor ampacity requirements for certain applications (dwelling units) and certain wire types.
Table 310.15(B)(6) allows the wire to be protected above its ratting as the NEC is well aware a dwelling unit service does not draw the full rating of the service.
