N.Y. General City Law § 46

§ 46. Registration; when required. Every employing or master plumber\ncarrying on his trade, business or calling in any city of this state\nshall register his name and address at the office of the board of health\nor the examining board of plumbers if so designated by local law of the\ncity in which he shall conduct such business, under such rules as the\nrespective boards of health or the local board of examining plumbers, in\nconjunction with the board of health of each of the cities shall\nprescribe, and thereupon he shall be entitled to receive a certificate\nof such registration, provided, however, that such employing or master\nplumber shall at the time of applying for such registration hold a\ncertificate of competency from an examining board of plumbers.\n