The switches are designed for normal operating conditions acc. to EN 62271¬1, Class "Minus 5 Indoor”. A proper functioning is also guaranteed up to temperatures of up to ¬15°C. The maximum value of the ambient temperature is 40°C; the average value over 24 hours is max. 35°C. The values of the insulating power are – acc. to EN 62271¬1 – are related to sea level. For altitudes up to 1000 m any reduction in insulation caused by the reduced insulating power of the air is insignificant and can be ignored. For an installation above 1000 m sea level it is necessary to correct the values given for the rated power¬frequency withstand voltag