N.Y. Comp. Codes R. & Regs. tit. 16, § 255.353 – Customer meters and regulators: location.

(a) Each meter and service regulator must be installed in a readily accessible location and be protected from corrosion and other damage, including any vehicular damage that may be anticipated.
(b) Each service regulator on new and replacement service lines, except for replacements by insertion, must be installed outside of the building, unless it is impractical or unsafe. Where the service regulator must be installed within the building, it is to be located as near as practical to the point of service line entrance. For service line replacements where the service regulator must remain inside, the regulator shall be tested and inspected in accordance with section 255.744(d) and (e) of this Part.
(c) The upstream regulator in a series must be located outside the building, unless it is located in a separate metering or regulating building.
(d) Each meter installed within a building must be located in a ventilated place and not less than three feet (914 millimeters) from any source of ignition or any source of heat which might damage the meter. The meter shall not be located under combustible stairways.
(e) When installing a new gas service for which gas pressure regulating and associated gas cleaning equipment and appurtenances is required for a building of public assembly, or apartment building, or building within an apartment, industrial or commercial complex, each with a capacity for normal occupancy of 75 or more persons, the following requirements shall be met:
1. (1) When outside installation is impracticable, regulations applicable to indoor installations with high pressure services shall pertain.
2. (2) The associated gas cleaning equipment and appurtenances may be located in the same area as the metering and/or pressure regulation equipment.
3. (3) Where practicable, the regulating and gas cleaning equipment shall be installed within a separate room that is designed for two-hour fire resistance, and is effectively sealed off from the remaining space in the building.
4. (4) In the case of indoor installations, special effort shall be made to prevent and indicate tampering by unauthorized persons.
5. (5) In all the above installations and on doors or accesses leading to all the above installations, a conspicuous notice shall be posted indicating the instructions for actions to be taken and the telephone number of the proper person to be called in the event a gas odor is detected.