3,500m altitude: $K_alt \approx 0.92$
| Altitude (m) | Approx. Factor | | :--- | :--- | | 0 – 2,000 | 1.00 | | 2,000 – 3,000 | 0.96 | | 3,000 – 4,000 | 0.92 | | > 4,000 | Engineering judgment | cable rating and derating factor
Trying a 240mm² cable (base rating ~ 450A): $450A \times 0.326 = 146.7A$ (Still slightly low). 3,500m altitude: $K_alt \approx 0
Correction factors for buried cables: | Soil Resistivity (K·m/W) | Correction Factor | | :--- | :--- | | 0.7 (Wet, marsh) | 1.05 – 1.10 | | 1.0 (Moist loam) | 1.00 | | 1.5 (Dry sand) | 0.85 | | 2.0 (Very dry gravel) | 0.70 | | 3.0 (Thermal backfill required) | 0.50 | 000 | 1.00 | | 2