How does high ambient temperature affect the Ampacity (current carrying capacity) of the cable?

Ampacity ratings are typically calculated based on a baseline ambient temperature of 30℃. As the surrounding environment gets hotter, the cable’s ability to dissipate its own internal electrical heat (I²R loss) diminishes drastically. Engineers must apply a Temperature Derating/Correction Factor. For example, a wire safely carrying 100 Amps at 30℃ may only be rated to safely carry 60 Amps in a 90℃  boiler room.