Cable: Derating Factor

Standard tables assume a specific reference temperature (e.g., 30°C in air, 20°C in ground). If the surrounding temperature is higher, the temperature differential between the cable and the environment is smaller, reducing heat dissipation.

The cable can safely carry only 73.5A , not 210A. To carry the intended load, a larger cable or improved installation (e.g., spaced cables, thermal backfill) is required. cable derating factor

While the math is simple, the application has nuances often missed in the field: Standard tables assume a specific reference temperature (e

Higher ambient temperature reduces heat dissipation. 30°C in air

Different regions approach derating with slightly different philosophies:

Ensures protective devices like circuit breakers operate correctly without tripping due to excessive heat in the conductors. Key Factors Affecting Cable Derating