2006 New York Code - Power Sources Of Smoke Detecting Devices.

 
    §  27-980  Power  sources  of  smoke detecting devices. Dwelling units
  shall be equipped with smoke detecting devices receiving  their  primary
  power  from  the  building  wiring and there shall be no switches in the
  circuit  other  than  the  over-current  device  protecting  the  branch
  circuit;  provided,  however,  that dwelling units in existing buildings
  may,  in  the  alternative,  be  equipped  with  battery-operated  smoke
  detecting devices except where such buildings are substantially improved
  or altered on or after January first, nineteen hundred eighty-two.