| mm² | Current in conduit (A) | Current in air (A) | |-----|------------------------|--------------------| | 1.5 | 15.5 | 19.5 | | 2.5 | 21 | 27 | | 4 | 28 | 37 | | 6 | 36 | 48 | | 10 | 50 | 66 | | 16 | 68 | 88 |
| Factor | Condition | Typical value | |--------|-----------|----------------| | k₁ – Ambient temp | 40°C (IEC) | 0.87 (PVC) | | k₂ – Grouping | 4 cables touching | 0.70 | | k₃ – Thermal insulation | Buried or in insulation | 0.70–0.85 | | k₄ – Altitude (>2000m) | 3000m | ~0.93 |
[ I_\textmin = \fracI_\textloadk_1 \times k_2 \times k_3 \dots ]