53 Pa. Stat. § 15322
All and every person or persons, desiring to engage in the business or trade of plumbing as a master plumber in cities of the first class, shall apply in person, and file an application, in writing, containing the recommendation of two registered master plumbers, certifying to the fact that such applicant has the necessary knowledge and experience and bears a good reputation, and the applicant shall have been a duly registered apprentice plumber for no less than four years, and a registered journeyman plumber for at least one year, prior to the filing of such application for license as master plumber, which application shall be made to the Department of Health, and after proper examination given by the Board of Plumbing Supervision of the Department of Health of said cities, if such person or persons so applying shall be found competent and the fee has been paid as hereinafter provided, the same shall be certified to the Director of Public Health of said cities, who shall, only to those so certified by the Board of Plumbing Supervision, issue a license and certificate of registration to such persons, certifying that they are registered master plumbers. Such license shall so long exist as such master plumbers shall comply with all the rules and regulations of the Department of Health and obey the provisions of this act, and shall entitle them to annually apply for a certificate permitting them to engage in, or work at, the trade of plumbing.
One desiring to secure the status of an apprentice shall cause his name to be recorded on the register or rolls of the Department of Health, at a cost to be fixed by the Director of the Department of Health, and, if approved, shall receive a card of registration. The employer of the apprentice shall certify on the said register or rolls that he is the certified licensed master plumber employing the apprentice. If the apprentice changes employers, each employer shall certify his employment of the apprentice. The apprentice shall be sixteen years of age or over: Provided, That every certified master plumber may employ one apprentice, and shall be entitled to employ not more than one additional apprentice for every four journeymen plumbers employed.
No one but a qualified plumber, as specified and provided for herein, may do plumbing work, however, a helper or laborer may work under the direction of such a qualified licensed plumber, performing only ordinary unskilled labor, such as: Excavating, drilling, cleaning, and moving.
53 P.S. § 15322