This class includes the installation of all kind of utilities that do the construction function as such. These activities are usually performed at the site of the construction, although parts of the job may be carried-out in a special shop.

Included are activities such as plumbing, installation of heating and air-conditioning systems, antennas, alarm systems and other electrical work, sprinkler systems, elevators and escalators, etc. Also included are insulation work (water, heat, sound), sheet metal work, industrial process piping work, commercial refrigerating work, the installation of illumination and signalling systems for roads, railways, airports, harbours, etc., and the installation of certain plants such as electric power and transformer plants, telecommunication and radar plants, etc. Also repair of the same type as the above mentioned activities is included.