I just wanted to run something by the forum to make sure I wasn’t missing anything. Here is the way I interpret it. Article 517.30(B)(1) breaks the Essential system down into two parts. The Emergency and the Equipment systems. The Emergency system is further broken down into the Life Safety Branch and the Critical Branch. Now, 517.30(C)(3) is titled "Mechanical protection of the Emergency System." This section applies to the emergency system (Life Safety and Critical) as defined above. Even though it does not specifically mention it, the Equipment System does not apply to this section and therefore is not required to be run in a non-flexible metallic wiring method.
Anyone disagree?!!

[This message has been edited by Nick (edited 05-08-2004).]