S.C. Code Ann. § 40-49-10: Certificate required to install sanitary plumbing.

It shall be unlawful for any person, be he master plumber, employing plumber or journeyman plumber, to install sanitary plumbing in any city or town having a population of fifteen thousand inhabitants or more, as fixed by the then most recent Federal census, until such person shall have made application to the local board of plumbing examiners, and shall have received from such board a certificate as to his qualifications to perform such work.