Ind. Code § 25-28.5-1-11

Sec. 11. It shall be unlawful for any person to act in the capacity of a plumbing contractor or journeyman plumber within this state without first obtaining a license as a plumbing contractor or journeyman plumber from the commission. This chapter however does not apply to helpers, laborers, registered apprentices, and other employees of a plumbing contractor or journeyman plumber, who do not in any manner hold themselves out to the public as being plumbers.