700.9(D)(1) Emergency feeder circuit wiring

[anbm]

To comply with 700.9(D)(1)...

What is the most cost efficiency method to run emergency feeder between electrical room #A to room #B in a high rise building if each elec. room locates at different floor and they are not stack?

 

[barbeer]

I personally have not used it, alot of posts on this forum praise MI cable.