Derating Factor For Cables |top| -

Soil’s ability to dissipate heat varies. Standard assumes ( R_th = 2.5 , K·m/W ) (damp soil). Dry or sandy soil reduces ampacity.

): Cables in free air cool best. Those buried, in conduits, or surrounded by (like fiberglass in a wall) require significant derating because heat is trapped. Burial Depth ( Cdcap C sub d derating factor for cables

Iz=Itabulated×K1×K2×K3…cap I sub z equals cap I sub t a b u l a t e d end-sub cross cap K sub 1 cross cap K sub 2 cross cap K sub 3 … Itabulatedcap I sub t a b u l a t e d end-sub Soil’s ability to dissipate heat varies

losses). A cable relies on the temperature differential between its core and the surrounding environment to shed this heat. When ambient air or ground temperatures exceed standard reference benchmarks (e.g., 30°C in air per IEC 60364-5-52 ), heat dissipation slows down. ): Cables in free air cool best