You size your service-entrance conductors per Table 310-15(b)(6). Why can't you size the 100 amp sub panel feeder conductors per Table 310-15(b)(6)? Me thinks some people are reading way too much into this example. Present company excluded! Like Don said, talk to the AHJ. IHMO the NEC Gods need to tie article 215-2(d) directly to Table 310-15(b)(6) and not article 310-15(b)(6). That would eliminate some, if not all, of the confusion. If it was me installing a sub panel, I would use Table 310-15(b)(6). [Linked Image]