N.Y.C. Admin. Code § 27-739: § 27-739 Yards and courts.

Where a building is classified in occupancy group J-1 or J-2, or where a building contains a space or spaces classified in occupancy group J-1 or J-2, all yards and courts shall be provided with adequate means of providing artificial light by electricity having a minimum intensity of not less than one foot candle measured at the lower level or levels of all yards or courts.