COMMERCIAL-wiring of public commercial, school and hospital buildings; the installation and repair of all equipment therein; and necessary pre-fabrication and preparation INDUSTRIAL-wiring of all industrial buildings and equipment; the maintenance, repair, and alteration of the same; and necessary pre-fabrication and preparation

RESIDENTIAL-wiring of residences, duplexes, and small apartment buildings and necessary pre-fabrication and preparation SPECIALIZED SYSTEMS-wiring of systems which include; sound, data transmission, telephone, fire alarm, fiber optics, energy management, closed circuit television programmable controllers, and nurse call systems