Derating Wire Jun 2026

Identify the wire you are using.

At higher altitudes, air density decreases, reducing convective cooling. The NEC (310.15(B)(3)(c)) mandates a correction factor of 0.95 to 0.80 depending on altitude. IEC 60364-2-2 has similar provisions. derating wire

Manual calculations are error-prone. Modern tools: Identify the wire you are using

This article explores the physics, the code-mandated calculations (NEC, IEC), the environmental variables, and the common traps engineers fall into when derating conductors. air density decreases