General building construction works, namely, building construction services, construction and repair of buildings, steel structure construction works; upholstering; machinery installation; electrical works, namely, electrical contractor services, installation of electrical systems and computer hardware; telecommunication wiring; repair or maintenance of vessels; aircraft maintenance or repair; repair or maintenance of automobiles; repair or maintenance of movie projectors; repair or maintenance of elevators and lifts; repair or maintenance of fire alarms; repair or maintenance of photographic machines and apparatus; repair or maintenance of office machines and apparatus; repair or maintenance of air-conditioning apparatus; repair or maintenance of computer hardware; telephone repair; repair or maintenance of construction machines and apparatus; burner maintenance or repair; repair or maintenance of boilers; pump repair or maintenance; repair of radio or television sets; repair or maintenance of freezing machines and apparatus