Standard reference conditions assume an ambient temperature of 30°C (86°F) for cables installed in air. When actual temperatures exceed this baseline, conductor ampacity must be reduced according to NEC Table 310. 15 (B) (1) or IEC 60364-5-52 Table B. This temperature is higher than the minimum operating temperature, and is eather, they should be kept in heated storage for at least 24 hours before instal om summer to winter, jacket movement and shrink. The minimum temperature at which a cable can be safely installed (bent, laid, or pulled) without damaging its insulation or sheath. Example: A PVC cable rated for -5°C installation temperature must not be installed in. Electrical derating is the systematic reduction of a conductor's current-carrying capacity (ampacity) to account for real-world installation conditions that deviate from standard testing environments.