NM (Romex) is prohibited above ceilings (except in some residential) even if they are not air handling spaces. Interesting what you said Ed about the "new" AC, probably going to cost about the same as MC but there is a slight labor savings by not having grounds to terminate. As far as I'm concerned everything should be MC, you treat your green grounds just like Romex grounds. If we did away with Romex it would put yet another nail in the fake science of arc-fault breakers, the biggest fraud on homeowners of all time.
-Hal
