125 Amp Cable Size at 20 Meters (415V Three-Phase (UK / Australia Industrial))
IEC 60364-5-52 metric conductor sizing (mm²), voltage drop, and power loss calculation for 125 A over 20 m (65.6 ft).
Copper Cable (≤3% Drop)35 mm²Drop: 2.65V (0.64%)
Aluminum Cable (≤3% Drop)70 mm²Drop: 2.18V (0.53%)
Voltage at Load412.4 VLine Loss: 573.2 W
Max Power & Breaker89.85 kW125A MCB/MCCB
IEC 60364 Cable Cross-Section Table (1.5 mm² – 400 mm²) for 125A at 20m
| Cross-Section (mm²) | Cu Ampacity | Al Ampacity | Cu Voltage Drop | Load Voltage | Al Voltage Drop | Power Loss | Status |
|---|---|---|---|---|---|---|---|
| 1.5 mm² | 16 A | 12 A | 61.78 V (14.89%) | 353.2 V | 101.9 V (24.55%) | 13375.0 W | Drop High |
| 2.5 mm² | 24 A | 18 A | 37.07 V (8.93%) | 377.9 V | 61.14 V (14.73%) | 8025.0 W | Drop High |
| 4 mm² | 32 A | 25 A | 23.17 V (5.58%) | 391.8 V | 38.21 V (9.21%) | 5015.6 W | Drop High |
| 6 mm² | 41 A | 32 A | 15.44 V (3.72%) | 399.6 V | 25.48 V (6.14%) | 3343.8 W | Drop High |
| 10 mm² | 57 A | 44 A | 9.27 V (2.23%) | 405.7 V | 15.29 V (3.68%) | 2006.2 W | Drop High |
| 16 mm² | 76 A | 59 A | 5.79 V (1.4%) | 409.2 V | 9.55 V (2.3%) | 1253.9 W | Drop High |
| 25 mm² | 101 A | 78 A | 3.71 V (0.89%) | 411.3 V | 6.11 V (1.47%) | 802.5 W | Drop High |
| 35 mm² | 125 A | 97 A | 2.65 V (0.64%) | 412.4 V | 4.37 V (1.05%) | 573.2 W | ✓ OK (≤3%) |
| 50 mm² | 151 A | 118 A | 1.85 V (0.45%) | 413.1 V | 3.06 V (0.74%) | 401.2 W | ✓ OK (≤3%) |
| 70 mm² | 192 A | 150 A | 1.32 V (0.32%) | 413.7 V | 2.18 V (0.53%) | 286.6 W | ✓ OK (≤3%) |
| 95 mm² | 232 A | 181 A | 0.98 V (0.24%) | 414.0 V | 1.61 V (0.39%) | 211.2 W | ✓ OK (≤3%) |
| 120 mm² | 269 A | 210 A | 0.77 V (0.19%) | 414.2 V | 1.27 V (0.31%) | 167.2 W | ✓ OK (≤3%) |
| 150 mm² | 309 A | 241 A | 0.62 V (0.15%) | 414.4 V | 1.02 V (0.25%) | 133.8 W | ✓ OK (≤3%) |
| 185 mm² | 353 A | 275 A | 0.5 V (0.12%) | 414.5 V | 0.83 V (0.2%) | 108.4 W | ✓ OK (≤3%) |
| 240 mm² | 415 A | 324 A | 0.39 V (0.09%) | 414.6 V | 0.64 V (0.15%) | 83.6 W | ✓ OK (≤3%) |
| 300 mm² | 477 A | 372 A | 0.31 V (0.07%) | 414.7 V | 0.51 V (0.12%) | 66.9 W | ✓ OK (≤3%) |
| 400 mm² | 570 A | 445 A | 0.23 V (0.06%) | 414.8 V | 0.38 V (0.09%) | 50.2 W | ✓ OK (≤3%) |
FAQ — 125 Amp Cable Size at 20 Meters (415V Three-Phase (UK / Australia Industrial))
What mm² cable size is required for 125A at 20 meters (415V)?
According to IEC 60364-5-52 ampacity and the 3% maximum voltage drop standard, you need 35 mm² copper cable for 125A over 20m at 415V (voltage drop: 2.65V or 0.64%).
What is the power capacity of 125A at 415V?
At unity power factor, 125A at 415V supports 89.85 kW with a standard 125A circuit breaker.
Related Lengths & Currents (415V)
125A · 5m (415V)125A · 10m (415V)125A · 15m (415V)125A · 25m (415V)125A · 30m (415V)125A · 35m (415V)125A · 40m (415V)125A · 45m (415V)125A · 50m (415V)125A · 60m (415V)125A · 70m (415V)10A · 20m (415V)16A · 20m (415V)20A · 20m (415V)25A · 20m (415V)32A · 20m (415V)40A · 20m (415V)50A · 20m (415V)63A · 20m (415V)80A · 20m (415V)100A · 20m (415V)160A · 20m (415V)200A · 20m (415V)