Cold-weather effects on Class I hazardous electrical installations

With electrical hazardous area installations in different climates around the world, it is increasingly difficult to test products for all temperature extremes. When standard testing for Class I explosion-proof equipment generally covers the temperature range of +40 to -25/spl deg/C (104 to -13/spl deg/F), how do you design for climates which may encounter much lower temperatures? In cold climate areas such as Alaska, Northern Canada, and Siberia, temperatures as low as -50 to -70/spl deg/C (-58 to -94/spl deg/F) may be encountered. Engineers are faced with making choices in specifying equipment for these areas with much greater extremes in ambient temperature conditions than standard testing accounts for, how do we ensure that the equipment will meet the intent of the standards involved? Some low-temperature testing has been done to determine the effect of low temperatures on explosion-proof equipment. However, there has not been sufficient work done to develop factors to predict performance at low temperatures that can be applied to normal temperature test results. Designers applying equipment in low-temperature applications will find it difficult to find complete information on low-temperature test results to assist them in applying equipment at temperatures below -25/spl deg/C (-13/spl deg/F).