What happens to the ampacity of a conductor if the ambient temperature exceeds 30°C (86°F)?

When the ambient temperature exceeds 30°C (86°F), the ampacity, or current-carrying capacity, of a conductor decreases. This occurs because conductors are rated for specific temperatures based on their ability to dissipate heat efficiently. As the ambient temperature rises above the maximum rating, the conductor can experience higher temperatures during operation, which can lead to overheating and a reduction in its effectiveness.

The National Electrical Code (NEC) provides guidelines and correction factors for ampacity based on temperature. For example, if a conductor is rated for a specific ampacity at 30°C, that rating will not hold true at higher temperatures without applying corrections. Therefore, when the ambient temperature increases, the safe current-carrying capacity of the conductor is reduced to prevent potential damage and ensure safety. This understanding is crucial for electrical installations to ensure that conductors are not overloaded at higher temperatures.