Copper 6 mm², 25 A, 20 m, 220 V
- Input
- 6 mm², 25 A, 20 m, 220 V → ΔV
- Expected output
- 2.87 V (1.30 %)
2 × 25 × 20 × 0.0172 ÷ 6.
Carregando ferramenta… / Loading tool…
voltage drop 6mm2 cable 20 meters
The tool opens with 25 A, 220 V, 20 m and 6 mm², copper at 20 °C and a 4 % limit. Change any field and the drop, the voltage at the load and the size table update.
2 × 25 × 20 × 0.0172 ÷ 6.
2 × 25 × 20 × 0.0172 ÷ 4.
2 × 25 × 20 × 0.0172 ÷ 10.
With ρ = 0.0282.
With ρ = 0.02058.
0.04 × 220 × 6 ÷ (2 × 25 × 0.0172).
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 %.
With 25 A in copper, 2.87 V, or 1.30 % of 220 V. The drop grows with current and with length.
Because the return path is already in the factor 2 of ΔV = 2 × L × I × ρ ÷ S.
No. It is only the voltage drop. Current capacity and protection are other criteria, for a licensed professional.
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.