N.D. Cent. Code § 43-18-11
No person, firm, corporation, or limited liability company shall engage in the business of a master plumber, journeyman plumber, or plumber's apprentice in any location of this state having a public system of waterworks or sewerage unless registered and licensed to do so by the board. Anyone not so licensed may do plumbing work which complies with the provisions of the minimum standards prescribed by the board on premises or that part of premises owned and actually occupied by the person as a residence, or may do plumbing repair on premises where the person is employed in full-time maintenance work, unless otherwise forbidden to do so by a local ordinance. Public water system employees may install and maintain service lines and water meters on premises served by the water system.
N.D.C.C. § 43-18-11