N.Y.C. Admin. Code § 27-396.4: § 27-396.4 Requirements.

Where required by this article or any other provision of this code, an emergency power system shall be provided. The emergency power system shall have a power source and fuel supply sufficient to operate the following equipment in accordance with rules and regulations promulgated by the department, where such equipment is required to be provided by this code:

(a) Fire pumps and booster pumps.

(b) At least three elevators at one time, with manual transfer to other elevators.

(c) Alarm systems.

(d) Communication systems.

(e) Emergency lighting, if battery packs are not provided.

(f) Ventilating systems used for smoke venting or control.

(g) Stair pressurization.