Voltage Drop Calculator – Single & Three Phase Cable Sizing Tool

Voltage Drop Calculator

Phase Type Single Phase (1Φ) Three Phase (3Φ)

Conductor Material Copper (Cu) Aluminum (Al)

Cable Size (mm²) 1.5 mm² 2.5 mm² 4 mm² 6 mm² 10 mm² 16 mm² 25 mm² 35 mm² 50 mm² 70 mm² 95 mm² 120 mm²

System Voltage (V) 230V 400V 415V

Cable Length (meters) Please enter a valid length

Load Current (Amperes) Please enter a valid current

Calculation Summary

Voltage Drop 0.00 V

Percentage Drop 0.00%

Status

PASS

Engineering Formulas Used

The calculation is based on standard IEC practices using DC resistance at 20°C as a baseline for typical low-voltage applications.

Single Phase: Vd = (2 × L × I × R) / 1000
Three Phase: Vd = (√3 × L × I × R) / 1000

• L: One-way length of the cable in meters.
• I: Design current in Amperes.
• R: Resistance of conductor in Ω/km.

Practical Engineering Notes

• Voltage Drop Limits: Generally ≤ 3% for lighting circuits and ≤ 5% for other uses (power) per BS 7671 / IEC standards.
• Cable Sizing: If the voltage drop exceeds limits, you must select a larger conductor cross-sectional area.
• Temperature Factors: These calculations use standard resistance values. High ambient temperatures may increase actual voltage drop.
• Verification: Always verify results with local electrical codes and official manufacturer data sheets.

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