37 Construction, installation, maintenance, repair and upgrade of fiber optic telecommunications equipment and systems comprised of such equipment, namely, repeaters, fiber optic light and image conduits, fiber optic transport equipment, fiber optic cables, power cables, electrical power supplies, computer hardware, optical transmitters, optical receivers, switches, multiplexers and repeater housing; construction, installation, maintenance, repair and upgrade of cabinets, shelves and trays that house telecommunications equipment; construction, installation, maintenance, repair and upgrade of buildings that house telecommunications equipment; construction, installation, maintenance, repair and upgrade of heating, ventilation and air conditioning equipment in buildings that house telecommunications equipment