1）Microwave machine rooms, decimeter wave machine rooms, metric wave machine rooms, substations and UPS rooms and other relatively enclosed electrical equipment inside radio and television transmission towers;
2）Program controlled switch rooms, control rooms and signaling transfer point rooms and other relatively enclosed internal electrical equipment for communication systems;
3）Control rooms, electronic equipment rooms, computer rooms, relay rooms, power transformation and distribution rooms, DC screens and UPS rooms, plasma equipment and primary fan frequency conversion rooms and other relatively enclosed electrical equipment inside power plants; cable crossings and concentrations, and cable shafts
4）Power transformation and distribution cabinets, elevator control cabinets, wire and cable ducts or bridges with cable trays;
5）Special or important cabinet equipment with relatively enclosed housings at other places.
