At what ambient temperature does the ampacity of conductors begin to be derated?

The ampacity of conductors begins to be derated at 86ºF. This temperature is significant because it is aligned with established electrical codes and standards which dictate that as the ambient temperature rises above this threshold, the ability of conductors to carry current without overheating decreases. Conductors are typically rated for maximum ampacity under standard ambient conditions, often set at 86ºF. If the ambient temperature exceeds this, heat generated by the current flow can lead to insulation breakdown and potential safety hazards. Therefore, proper derating is necessary to ensure the electrical system operates safely and efficiently in higher temperatures.

In contexts where temperatures approach or exceed this point, adjustments must be made to the expected current load, so that the thermal effects on the conductor material and its insulation can be effectively managed. This is crucial for maintaining the longevity and reliability of electrical installations.