"Apprentice plumber" means a person who is registered as such and who is undergoing an apprenticeship or course of training, not exceeding five years, for the purpose of learning the trade of plumbing. An apprentice, as herein defined, shall perform no work regulated by this Plumbing Code, or amendments hereto, except as an assistant, under the direct supervision of a master plumber, and in the immediate presence of a licensed master plumber or a licensed journeyman plumber.
(1957 Code §1123.02)