D.C. Code § 34-209
The term "gas company" when used in this subtitle includes every corporation, company, association, joint-stock company or association, partnership, or person manufacturing, making, distributing, or selling gas for light, heat, or power, or for any public use whatsoever in the District of Columbia, their lessees, trustees, or receivers, appointed by any court whatsoever, and in said district selling, physically transmitting, or distributing natural gas in the District of Columbia to retail natural gas customers. The term excludes any building owner, lessee, or manager who, respectively, owns, leases, or manages, the internal distribution system serving the building and who supplies natural gas and other related natural gas services solely to occupants of the building for use by the occupants.
D.C. Code § 34-209