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Voltage Drop Calculator
Size your generator cables correctly. Input your cable run and load, and we'll calculate voltage drop and recommend the right cable cross-section.
One-way distance from generator to load
400V standard for 3-phase, 230V for 1-phase
Voltage Drop
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Drop %
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Voltage at Load
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Max Cable Length
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Voltage Drop Formula
For AC 3-phase circuits, the voltage drop is calculated using:
Vd = (2 x L x I x R) / 1000
Where:
- Vd = voltage drop in volts
- L = one-way cable length in meters
- I = load current in amperes
- R = conductor resistance in Ω/km (depends on material and cross-section)
Maximum Allowable Voltage Drop
Industry standards recommend the following limits:
| Application | Max Voltage Drop |
|---|---|
| Generator to main panel | ≤ 1% |
| Main panel to sub-panel | ≤ 2% |
| Sub-panel to load | ≤ 3% |
| Combined (total circuit) | ≤ 5% |