6 mm² copper (≈ 8 AWG) carries 32 A over 25 m with a 2.56% drop (5.9 V) and 189 W of loss.
Recommended cable
6 mm²
≈ 8 AWG · copper
Voltage drop
2.56%
5.9 V of 230 V · limit 3%
Power loss in cable
189W
2.56% of 7.36 kW
Current
32A
cos φ 1
Min. size for voltage drop
6 mm²
exact 4.96 mm²
Min. size for current
4 mm²
Clipped direct to wall or tray, 30 °C
Current capacity of chosen size
46A
ambient factor 1
Max length at this size
29m
for a 3% drop
Energy lost per year
189kWh
at 1,000 full-load hours
Cable size comparison
| Size | AWG ≈ | Drop % | Drop V | Loss W | Capacity A | Max length m | OK? |
|---|---|---|---|---|---|---|---|
| 1 mm² | 16 AWG | 15.07% | 34.65 | 1,109 | 16 | 5 | ✗ current |
| 1.5 mm² | 14 AWG | 10.07% | 23.16 | 741 | 20 | 7 | ✗ current |
| 2.5 mm² | 12 AWG | 6.17% | 14.19 | 454 | 27 | 12 | ✗ current |
| 4 mm² | 10 AWG | 3.84% | 8.83 | 282 | 36 | 20 | ✗ drop |
| 6 mm² ◀ | 8 AWG | 2.56% | 5.9 | 189 | 46 | 29 | ✓ |
| 10 mm² | 6 AWG | 1.52% | 3.5 | 112 | 63 | 49 | ✓ |
| 16 mm² | 4 AWG | 0.96% | 2.2 | 70 | 85 | 78 | ✓ |
| 25 mm² | 3 AWG | 0.61% | 1.39 | 45 | 112 | 124 | ✓ |
| 35 mm² | 1 AWG | 0.44% | 1 | 32 | 138 | 172 | ✓ |
| 50 mm² | 1/0 AWG | 0.32% | 0.74 | 24 | 168 | 233 | ✓ |
| 70 mm² | 3/0 AWG | 0.22% | 0.51 | 16 | 213 | 336 | ✓ |
| 95 mm² | 4/0 AWG | 0.16% | 0.37 | 12 | 258 | 467 | ✓ |
- Voltage drop: ΔV = 2 × L × I × (R·cos φ + X·sin φ), with IEC 60228 conductor resistance corrected to 70 °C and 0.08 mΩ/m reactance.
- Current capacity is indicative, from IEC 60364-5-52 tables (PVC/XLPE, method factors, ambient and grouping corrections). Your national wiring rules (BS 7671, NEC 310, VDE 0298-4…) and the protective device rating decide the final size.
- Motor starting currents (5–7× nominal) cause brief extra drops, so check starting conditions on long motor feeders.