According to NFPA 496 (item 5-4.9)"The electrical power for the positive pressure air system shall be taken off the main power line ahead of any service disconnects to the control room or shall be supplied from a separate power source." What does exactly mean? In my case, I have a Control Building along with a Motor Control Center Room (class 1, div 2, G2). Do I have to take the corresponding MCC out? Do I have to make the corresponding control and switch panel appropiate for Class I, Div 2, Group D?