D.C. Mun. Regs. tit. 17, r. 17-315
No person shall perform work without having been issued the license under which that work may be performed. The license must be currently valid and in full force and effect.
Any license that is changed or altered shall be void.
If a license is lost, destroyed, or defaced, the licensee shall present a statement to that effect, properly notarized, and a duplicate license will be issued on payment of a fee of one dollar ($1) to those persons who can show good cause.
No person holding a license under this chapter shall suffer or allow any other person to use or operate under that license.
No license shall be assigned or transferred.
No licensee, in making an installation, shall create a violation of any other regulations.
No Master Refrigeration and Air Conditioning Mechanic or Master Refrigeration and Air Conditioning Mechanic Limited shall be responsible for the work of more than one (1) contractor.
No person without a license required by this chapter may perform any air conditioning or refrigeration work in the District of Columbia except in buildings under the control of the officer in charge of Public Buildings and Grounds or of the Architect of the Capitol.
No person shall display a sign stating or implying that he or she is conducting a business requiring a license under this chapter, unless her or she is licensed to do so as provided in this chapter.
No person shall advertise by means of business cards, stationery, or any publication or directory, or claim orally to a prospective customer, or otherwise indicate that he or she is conducting an air conditioning and refrigeration business, unless he or she is licensed to do so as provided in this chapter.
Any person who violates any rule or section of this chapter, shall, upon conviction, be punished by a fine of not more than three hundred dollars ($300) or imprisonment of not more than ninety (90) days.
D.C. Mun. Regs. tit. 17, r. 17-315