20 A at 220 V, 30 m
- Input
- 2.5 mm², 20 A, 30 m, 220 V → ΔV
- Expected output
- 8.26 V (3.75 %)
2 × 20 × 30 × 0.0172 ÷ 2.5.
Carregando ferramenta… / Loading tool…
voltage drop 2.5 mm2 30 meters
The tool opens with 30 m and 2.5 mm². Adjust the current and voltage for your case and check in the table which sizes keep the drop under the limit you set.
2 × 20 × 30 × 0.0172 ÷ 2.5.
2 × 16 × 30 × 0.0172 ÷ 2.5.
2 × 10 × 30 × 0.0172 ÷ 2.5.
2 × 15 × 20 × 0.0172 ÷ 1.5.
2 × 20 × 30 × 0.0172 ÷ (0.04 × 220).
2 × 16 × 30 × 0.0172 ÷ (0.04 × 230).
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 %.
It depends on the current: 8.26 V with 20 A at 220 V, 6.60 V with 16 A at 230 V. The drop is proportional to current.
With 20 A at 220 V, L = 0.04 × 220 × 2.5 ÷ (2 × 20 × 0.0172) = 32 m. The tool shows this maximum length for any current.
The tool does not attribute any percentage to a code. The limit is your own field; check the code in force or the designer.
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.