It is unlawful for any journeyman plumber to do plumbing work within the corporate limits of the City unless such work is done by employment of such journeyman plumber by a plumbing contractor or master plumber. All plumbing work done within the corporate limits of the City shall be done under contract or agreement with a plumbing contractor or master plumber and any such plumbing work done by a journeyman plumber within the corporate limits of the City shall be under employment by a plumbing contractor. Should any journeyman plumber perform plumbing work within the corporate limits of the City except under employment by a plumbing contractor, such shall be deemed an offense and a violation of this Code. (1988 Code § 5-205)