Enter system type, load current, cable length, conductor material and allowable drop to get a live voltage drop and a recommended minimum cross-section. Built for early-stage single-phase / three-phase sizing checks.
| Size (mm²) | Resistance (mΩ/m) | Size (mm²) | Resistance (mΩ/m) |
|---|---|---|---|
| 1.5 | 14.933 | 50 | 0.448 |
| 2.5 | 8.960 | 70 | 0.320 |
| 4 | 5.600 | 95 | 0.236 |
| 6 | 3.733 | 120 | 0.187 |
| 10 | 2.240 | 150 | 0.149 |
| 16 | 1.400 | 185 | 0.121 |
| 25 | 0.896 | 240 | 0.093 |
| 35 | 0.640 | 300 | 0.075 |
Resistance uses ρ=0.0224 Ω·mm²/m (conservative, ~70–90°C conductor temperature). Actual values vary with temperature and installation; final selection should follow IEC 60228 / IEC 60502 and BS 7671 tables.
Resistance per unit length R = ρ / A (ρ resistivity, A area), combined with reactance X and power factor: single-phase Vd = 2×I×L×(R·cosφ + X·sinφ), three-phase Vd = √3×I×L×(R·cosφ + X·sinφ). Divide by the rated voltage for the percentage drop. This tool applies that logic for an early-stage check.
It iterates standard IEC 60228 sizes (1.5, 2.5, 4 … 300 mm²) from smallest up and picks the first one whose drop percentage ≤ your "allowable drop". This guarantees the drop stays within limit at that current and length — the voltage-drop-based lower bound for sizing.
This tool covers the voltage-drop dimension of sizing. Final selection must also check current-carrying capacity (installation method, ambient temperature, grouping, buried/tray per IEC 60502 / BS 7671 ampacity tables) and short-circuit thermal stability. Send the calculation with your application scenario and our engineers will confirm the size and quote.
