As used in this chapter:
1. “Apprentice plumber” means a person who labors at the trade of plumbing as an employee of a plumbing contractor under the direct supervision and in the immediate presence of a plumbing contractor or journeyman plumber.
2. “Journeyman plumber” means a person who labors at the trade of plumbing as an officer, partner, or employee of a plumbing contractor.
3. “Master plumber” means a person who labors at the trade of plumbing and works in the planning or superintending of the design, installation, or repair of plumbing, HVAC, refrigeration, or hydronic systems, and who is familiar with the laws and rules governing the same.
4. “Plumbing contractor” means a person who is engaged in the business of contracting to make plumbing installations, repairs, and alterations.