When the installation, extension, alteration, or repair of an elevator, moving stairway, mechanical equipment, refrigeration, air conditioning or ventilating apparatus, plumbing, gas piping, electric wiring, heating system, fire sprinkler system, or any other equipment is subject to a requirement of this Chapter, it shall be unlawful to use the equipment until the Director issues a certificate approving the work. (1975 L.M.C., ch. 1, § 1; 2003 L.M.C., ch. 23, § 1.)