N.Y. Comp. Codes R. & Regs. tit. 16 § 461.9
Each utility shall record each month the estimated amount of depreciation accrued during that month on steam plant and on the portion of common utility plant applicable to steam operations. (See account 503, depreciation, account 250, reserve for depreciation of steam plant, and account 253.2, reserve for depreciation and amortization of common utility plant.)
Note A:
Depreciation expense applicable to property included in account 102, steam plant leased to others, shall be charged to account 508.2, expenses of steam plant leased to others.
Note B:
Depreciation applicable to transportation, stores, shop, and laboratory equipment, and to tools and work equipment shall be charged to clearing accounts provided herein; all depreciation on structures shall be charged to account 503, depreciation.
Note C:
The accounting for depreciation of utility plant in other departments which are subject to regulation by the commission shall be in accordance with the effective systems of accounts applicable to such operations.
N.Y. Comp. Codes R. & Regs. Tit. 16 § 461.9