MI cable for critical branch wiring

[mshields]

I know that as of the 2014 code, MI cable is no longer needed for the Critical branch; i.e. by virtue of the fact that it is no longer considered half of the Emergency system and therefore does not need to be installed in accordance with Article 700. That said, the hospital I do work for still wants it. So I've run into a situation where we are putting a compressed medical air circuit on the Critical branch. This load is listed in 517.34 as being appropriately served by the Equipment branch but some where in there it says that "it may be put on Critical". My question is, if we go by the 2011 code, does the feeder to the disconnect for this equipment need to be 2 hour rated.

I guess the question is really a generic one. Where 2 hour rated feeders are required, does that include a feeder to the equipment or is that just for the distribution network.

 

[Pharon]

I don't see anywhere in 700.10(D)(1) where it exempts certain types of feeders.

If it's a feeder to a piece of equipment's OCPD, then I would think it needs to be 2-hour rated.

If there's no OCPD at the equipment, then it's a branch circuit, and the 2-hour rating does not apply.