Derating Factor Of Cable -

For underground cables, the deeper a cable is buried, the harder it is for heat to reach the surface and dissipate. While the ground is cooler at depth, the thermal resistance of the soil layers above acts as an insulator. 4. Soil Thermal Resistivity ( Ksoilcap K sub s o i l end-sub

, the cable is already "pre-warmed." It can't handle as much extra heat from electrical current. Scenario: At 40∘C40 raised to the composed with power C

Derating factors are (usually less than 1.0) applied to a cable's base capacity to account for these environmental stressors. The Three Enemies of Capacity

The surrounding medium dictates thermal resistance:

Running a cable through attic insulation or burying it deep in dry soil traps heat like a heavy coat.