I don't like answering threads like this; they tend to lead to too much speculation from lack of knowledge of the actual installations involved.
First, I would have been a bit (only a bit) more comfortable if you had described the "armored cable" as MC-HL. That would have at least given me some confidence that there was a knowledgeable person behind the question. (You already acknowledged you?re new to Class I, Division1)
That said, begin in Section 501.10(A)(2); it will lead you to Section 501.140. Be VERY careful that your application is one listed in Subsections 501.140(A)(1) through(5). To be honest, your current description isn?t too promising.