Section 27-979. Smoke detecting devices; where required

(a)  On  and  after  January  first,  nineteen hundred eighty-two, all
  dwelling units within occupancy  group  J-1  and  occupancy  group  J-2,
  except  such  units  which  contain  operational automatic wet sprinkler
  systems pursuant to article four of this subchapter, and dwelling  units
  in  buildings within occupancy group J-3 shall be equipped with approved
  and  operational  smoke  detecting  devices  as  hereinafter   provided.
  Buildings  within  occupancy  group  J-1  may,  in  the  alternative, be
  equipped with a line-operated zoned smoke detecting system with  central
  annunciation  and  central  office  tie-in  for all public corridors and
  public spaces, pursuant to rules  and  regulations  promulgated  by  the
  commissioner.  The  commissioner  may, upon good cause shown, extend the
  period of compliance for occupancy groups J-1 and J-2 to June thirtieth,
  nineteen hundred eighty-two.
    (b)  Approved  and  operational  smoke  detecting  devices  shall   be
  installed in mechanical rooms, electrical switch gear rooms and electric
  and  telephone closets over seventy-five square feet in gross floor area
  in all buildings in all occupancy groups.