Let me see if I understand the question.. We have a 30" nipple that goes into a wireway with six 12/2 romexes entering the wireway and the question is can the jacket be removed from the point of entrance to the wireway all the way to the ocpd?
assuming I understand the question?
and on an exam if I were asked, I would say no.
The length of the wireway plays on my mind in conjunction with the conductors needing to be marked.
also I'm not sure 300-15 (f) applies .
I think what we have is a raceway and not a sleeve to protect cable assemblies