2016 New York Laws
GCT - General City
Article 4 - (General City) PLUMBING AND DRAINAGE
46 - Registration; when required.

 46. Registration;  when  required. Every employing or master plumber
  carrying on his trade, business or calling in any  city  of  this  state
  shall register his name and address at the office of the board of health
  or  the examining board of plumbers if so designated by local law of the
  city in which he shall conduct such business, under such  rules  as  the
  respective boards of health or the local board of examining plumbers, in
  conjunction  with  the  board  of  health  of  each  of the cities shall
  prescribe, and thereupon he shall be entitled to receive  a  certificate
  of  such  registration, provided, however, that such employing or master
  plumber shall at the time of  applying  for  such  registration  hold  a
  certificate of competency from an examining board of plumbers.