Section 28-408.6. Master plumber business

No  individual,  corporation,
  partnership or other  business  association  shall  conduct  a  plumbing
  contracting  business  in  the  city  of  New  York,  or employ the name
  "plumber" or "plumbing" in its business name unless such business  is  a
  master plumber business as follows:
    1.  No less than 51 percent of the control and voting capital stock of
  such entity is owned by one or more individuals who are licensed  master
  plumbers, except as otherwise provided;
    2.  All  plumbing  or  gas  piping  work  performed  by such entity is
  performed by or under the direct  and  continuing  supervision  of  such
  licensed master plumber;
    3.  The person in charge of such work is such licensed master plumber;
  and
    4. The persons actually performing such work are in the direct  employ
  of such master plumber business as authorized by the code.
    Exception:  A  company,  corporation,  partnership  or  other business
  association or its predecessor that was engaged in plumbing  work  prior
  to  January  25,  1990  may continue to do so in any one or more of such
  business forms without complying with the foregoing, if (i)  application
  was  made  to  the department prior to July 25, 1990, and (ii) necessary
  evidence was furnished on or  prior  to  January  25,  1991,  that  such
  company,  corporation,  partnership or other business association or its
  predecessor had employed an average of ten or more  journeymen  plumbers
  doing  plumbing  work  for  at least five days a week for a period of 10
  years or more out of the twenty years preceding July 25, 1990, provided,
  that  such  plumbing  business  continues  to  have  all  plumbing  work
  conducted  under the management and direct and continuing supervision of
  a licensed master plumber in the direct employ of such plumbing business
  and that such licensed master plumber is not  otherwise  interested  in,
  associated  with or employed by any other plumbing business operating in
  this city except as a joint  venture  in  which  such  master  plumber's
  employer is one of the joint venturers.