This class includes the specialized installation of machinery. However, the installation of equipment that forms an integral part of buildings or similar structures, such as installation of escalators, electrical wiring, burglar alarm systems or air-conditioning systems, is classified as construction.

This class includes:
——installation of industrial machinery in industrial plant
——installation of industrial process control equipment
——installation of other industrial equipment, e.g.: communications equipment; mainframe and similar computers; irradiation and electromedical equipment, etc.
——dismantling large-scale machinery and equipment
——activities of millwrights
——machine rigging
——installation of bowling alley equipment

This class excludes:
——installation of electrical wiring, burglar alarm systems, see 4321
——installation of air-conditioning systems, see 4322
——installation of elevators, escalators, automated doors, vacuum cleaning systems, etc., see 4329
——installation of doors, staircases, shop fittings, furniture etc., see 4330
——installation (setting-up) of personal computers, see 6209