D.C. Mun. Regs. tit. 17, r. 17-304
A license as a Refrigeration and Air Conditioning Contractor shall entitle the licensee to engage in the business of installing, maintaining, repairing, or replacing any refrigerating or air conditioning system, including components of a system, subject to the limitations set forth in § 301 and § 305 through § 307.
A license as a Master Refrigeration and Air Conditioning Mechanic shall entitle the licensee to supervise or perform any work required in connection with the installation, maintenance, repair, or replacement of any refrigeration or air conditioning system, including the components of a system, regardless of the size and nature of the system, subject to the limitations set forth in § 301.
A license as a Master Refrigeration and Air Conditioning Mechanic Limited shall entitle the licensee to supervise or perform any work required in connection with the installation, maintenance, repair, or replacement of refrigeration or air conditioning systems up to and including twenty-five (25) compressor horsepower or the equivalent tons of refrigeration in the aggregate, subject to the limitations set forth in § 301.
Each person, firm, or corporation making application for a license to be engaged or employed in the business of installing, maintaining, repairing, and replacing refrigeration and air conditioning equipment as a refrigeration and air conditioning contractor shall comply with the specific requirements for the license applied for, as set forth in § 305 through § 307.
D.C. Mun. Regs. tit. 17, r. 17-304