For special service conditions, the subscribers shall agree on with the manufactures. Generally, the conditions are under consideration as follows:
        The altitude of the service place is exceeding 1000m, because of which the external intensity of insulation would decline; Plateau-type here is the best choice.
Service environment with High temperature, due to which, the circuit-breaker need reduce the rated current or with forced ventilation equipment.
        Mounted under the special climatic conditions. Generally, the indoor-type switchgear cannot be mounted under the condition of high temperature and sharply changeable climate. Otherwise, preventative measures must be made such as mounting an electriheater to eliminate the phenomena of condensation as well as prevention of erosion or other contamination.