10 mm², 30 A, 50 m, 380 V
- Input
- 10 mm², 30 A, 50 m, 380 V trifásico → ΔV
- Expected output
- 4.47 V (1.18 %)
√3 × 30 × 50 × 0.0172 ÷ 10.
Carregando ferramenta… / Loading tool…
three phase voltage drop calculator
The tool opens in three-phase. Enter the LINE-TO-LINE voltage, the line current, the one-way length and the size; the drop in V and % is computed for a balanced load.
√3 × 30 × 50 × 0.0172 ÷ 10.
√3 × 40 × 100 × 0.0172 ÷ 16.
Same volts of drop, larger percentage.
With ρ = 0.0282.
3 × 30² × 0.086.
√3 × 30 × 50 × 0.0172 ÷ (0.04 × 380).
In DC or single-phase, ΔV = 2 × L × I × ρ ÷ S, with L in meters, I in amps, ρ in Ω·mm²/m and S in mm². For copper at 20 °C, 20 m, 25 A and 6 mm²: 2 × 20 × 25 × 0.0172 ÷ 6 = 2.87 V. At 220 V that is 1.30 %.
ΔV = √3 × L × I × ρ ÷ S, with the line current and the one-way length, for a balanced load.
The calculated drop is line-to-line; the percentage divides by the line-to-line voltage.
The formula assumes a balanced load. With different loads per phase, calculate each phase separately with its own current.
Length is the one-way distance from the source to the load. The return path is already in the math.
Resistivity used: 0.0172 Ω·mm²/m.
Resistivity at 20 °C: annealed copper 1.72e-8 Ω·m (0.0172 Ω·mm²/m) and aluminum 2.82e-8 Ω·m (0.0282 Ω·mm²/m), temperature coefficients 0.00393 and 0.0039 per kelvin (Wikipedia, Electrical resistivity and conductivity).
| mm² | ΔV (V) | ΔV (%) | Voltage at the load | Cable loss | Meets |
|---|---|---|---|---|---|
| 34.4 | 15.64 | 185.6 | 860 | ✗ | |
| 22.93 | 10.42 | 197.1 | 573.3 | ✗ | |
| 17.2 | 7.818 | 202.8 | 430 | ✗ | |
| 11.47 | 5.212 | 208.5 | 286.7 | ✗ | |
| 6.88 | 3.127 | 213.1 | 172 | ✓ | |
| 4.3 | 1.955 | 215.7 | 107.5 | ✓ | |
| 2.867 | 1.303 | 217.1 | 71.67 | ✓ | |
| 1.72 | 0.7818 | 218.3 | 43 | ✓ | |
| 1.075 | 0.4886 | 218.9 | 26.87 | ✓ | |
| 0.688 | 0.3127 | 219.3 | 17.2 | ✓ | |
| 0.4914 | 0.2234 | 219.5 | 12.29 | ✓ | |
| 0.344 | 0.1564 | 219.7 | 8.6 | ✓ | |
| 0.2457 | 0.1117 | 219.8 | 6.143 | ✓ | |
| 0.1811 | 0.0823 | 219.8 | 4.526 | ✓ | |
| 0.1433 | 0.06515 | 219.9 | 3.583 | ✓ | |
| 0.1147 | 0.05212 | 219.9 | 2.867 | ✓ | |
| 0.09297 | 0.04226 | 219.9 | 2.324 | ✓ | |
| 0.07167 | 0.03258 | 219.9 | 1.792 | ✓ | |
| 0.05733 | 0.02606 | 219.9 | 1.433 | ✓ |
Limit of this tool. It calculates only the voltage drop from conductor resistance. It does not check ampacity, heating, overcurrent protection or any code minimum size, and it does not size the cable. That depends on the design and belongs to a licensed professional following your local electrical code.