40 Amp Cable Size at 120 Meters (24V DC (Off-Grid Solar / Industrial Control))
IEC 60364-5-52 metric conductor sizing (mm²), voltage drop, and power loss calculation for 40 A over 120 m (393.7 ft).
Copper Cable (≤3% Drop)300 mm²Drop: 0.68V (2.85%)
Aluminum Cable (≤3% Drop)400 mm²Drop: 0.85V (3.53%)
Voltage at Load23.3 VLine Loss: 27.4 W
Max Power & Breaker0.96 kW40A MCB/MCCB
IEC 60364 Cable Cross-Section Table (1.5 mm² – 400 mm²) for 40A at 120m
| 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 | 136.96 V (570.67%) | 0.0 V | 225.92 V (941.33%) | 5478.4 W | Drop High |
| 2.5 mm² | 24 A | 18 A | 82.18 V (342.4%) | 0.0 V | 135.55 V (564.8%) | 3287.0 W | Drop High |
| 4 mm² | 32 A | 25 A | 51.36 V (214.0%) | 0.0 V | 84.72 V (353.0%) | 2054.4 W | Drop High |
| 6 mm² | 41 A | 32 A | 34.24 V (142.67%) | 0.0 V | 56.48 V (235.33%) | 1369.6 W | Drop High |
| 10 mm² | 57 A | 44 A | 20.54 V (85.6%) | 3.5 V | 33.89 V (141.2%) | 821.8 W | Drop High |
| 16 mm² | 76 A | 59 A | 12.84 V (53.5%) | 11.2 V | 21.18 V (88.25%) | 513.6 W | Drop High |
| 25 mm² | 101 A | 78 A | 8.22 V (34.24%) | 15.8 V | 13.56 V (56.48%) | 328.7 W | Drop High |
| 35 mm² | 125 A | 97 A | 5.87 V (24.46%) | 18.1 V | 9.68 V (40.34%) | 234.8 W | Drop High |
| 50 mm² | 151 A | 118 A | 4.11 V (17.12%) | 19.9 V | 6.78 V (28.24%) | 164.4 W | Drop High |
| 70 mm² | 192 A | 150 A | 2.93 V (12.23%) | 21.1 V | 4.84 V (20.17%) | 117.4 W | Drop High |
| 95 mm² | 232 A | 181 A | 2.16 V (9.01%) | 21.8 V | 3.57 V (14.86%) | 86.5 W | Drop High |
| 120 mm² | 269 A | 210 A | 1.71 V (7.13%) | 22.3 V | 2.82 V (11.77%) | 68.5 W | Drop High |
| 150 mm² | 309 A | 241 A | 1.37 V (5.71%) | 22.6 V | 2.26 V (9.41%) | 54.8 W | Drop High |
| 185 mm² | 353 A | 275 A | 1.11 V (4.63%) | 22.9 V | 1.83 V (7.63%) | 44.4 W | ~ ≤5% |
| 240 mm² | 415 A | 324 A | 0.86 V (3.57%) | 23.1 V | 1.41 V (5.88%) | 34.2 W | ~ ≤5% |
| 300 mm² | 477 A | 372 A | 0.68 V (2.85%) | 23.3 V | 1.13 V (4.71%) | 27.4 W | ✓ OK (≤3%) |
| 400 mm² | 570 A | 445 A | 0.51 V (2.14%) | 23.5 V | 0.85 V (3.53%) | 20.5 W | ✓ OK (≤3%) |
FAQ — 40 Amp Cable Size at 120 Meters (24V DC (Off-Grid Solar / Industrial Control))
What mm² cable size is required for 40A at 120 meters (24V)?
According to IEC 60364-5-52 ampacity and the 3% maximum voltage drop standard, you need 300 mm² copper cable for 40A over 120m at 24V (voltage drop: 0.68V or 2.85%).
What is the power capacity of 40A at 24V?
At unity power factor, 40A at 24V supports 0.96 kW with a standard 40A circuit breaker.
Related Lengths & Currents (24V)
40A · 5m (24V)40A · 10m (24V)40A · 15m (24V)40A · 20m (24V)40A · 25m (24V)40A · 30m (24V)40A · 35m (24V)40A · 40m (24V)40A · 45m (24V)40A · 50m (24V)40A · 60m (24V)40A · 70m (24V)10A · 120m (24V)16A · 120m (24V)20A · 120m (24V)25A · 120m (24V)32A · 120m (24V)50A · 120m (24V)63A · 120m (24V)80A · 120m (24V)100A · 120m (24V)125A · 120m (24V)160A · 120m (24V)200A · 120m (24V)