Re: coemergency backup power code for outpatient facilities?
If they are using general anesthesia, I'm sure the emergency power is required. But I don't know which code requires it off hand.
It could be the NEC, or NFPA 99, or NFPA 101 or 110. Or your local AHJ might have some specific requirement.
In addition, all surgery centers (at least in this state) require the state dept. of public health to review and approve the plans (and conduct inspections). I really doubt if they will OK a surgery center without em. power unless it is a "bumps" and "bruises" type operation only (i.e. local anesthesia only).
Steve