Cable Cross-Section Calculator
Determine the minimum cable cross-section for your electrical installation.
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Cable Sizing Standards
This calculator uses IEC 60364 principles. The minimum cross-section is determined by both current-carrying capacity and voltage drop. Always verify with local electrical codes and a qualified electrician.
Cable Sizing Fundamentals
Choosing the correct cable cross-section is critical for electrical safety and efficiency. An undersized cable can overheat, cause voltage drop, and create fire hazards. This calculator helps you determine the minimum conductor size based on current-carrying capacity and permissible voltage drop.
Voltage Drop Calculation
The voltage drop in a cable is determined by the current, cable length, conductor material, and cross-sectional area. For a single-phase circuit:
For a three-phase circuit:
Where ρ is the resistivity (0.0175 Ω·mm²/m for copper, 0.0294 Ω·mm²/m for aluminum), L is the one-way cable length in meters, I is the current in amperes, and A is the cross-section in mm².
Standard Cross-Section Sizes (mm²)
IEC standard sizes: 0.5, 0.75, 1, 1.5, 2.5, 4, 6, 10, 16, 25, 35, 50, 70, 95, 120, 150, 185, 240, 300 mm². The calculator always selects the next larger standard size above the calculated minimum.
Engineering Applications
- Building wiring: Size cables for lighting circuits, power outlets, and appliance feeders according to local electrical codes.
- Industrial installations: Determine cable sizes for motors, pumps, and machinery in factories and plants.
- Renewable energy: Size DC cables between solar panels, charge controllers, and battery banks where voltage drop is critical.
- LED display systems: Calculate cable sizes for power distribution in large LED video walls and signage installations.
- EV charging: Determine appropriate cable sizes for electric vehicle charging stations and home charger installations.
AWG to mm² Conversion
The American Wire Gauge (AWG) system is commonly used in North America. Key equivalents: AWG 14 ≈ 2.08 mm², AWG 12 ≈ 3.31 mm², AWG 10 ≈ 5.26 mm², AWG 8 ≈ 8.37 mm², AWG 6 ≈ 13.3 mm². A lower AWG number means a larger wire diameter.
Frequently Asked Questions
What voltage drop percentage should I use?
The IEC 60364 standard recommends a maximum of 3% voltage drop for lighting circuits and 5% for other electrical equipment. For non-critical loads (like heaters), 10% may be acceptable. Always check your local electrical code requirements.
Should I use copper or aluminum cables?
Copper has lower resistivity and higher current capacity per mm², making it the preferred choice for most installations. Aluminum is lighter and cheaper, often used for overhead power lines and large feeder cables. For the same current capacity, an aluminum cable needs approximately 1.6× the cross-section of copper.
Does cable length mean one-way or round-trip distance?
Enter the one-way distance. The calculator automatically accounts for the round-trip (2× for single phase, √3× for three phase) in its voltage drop calculation.
Why is my calculated cable size larger than expected?
Long cable runs and high currents cause significant voltage drops, requiring larger cables than you might expect. If the calculated size seems too large, consider: shortening the cable route, using a higher supply voltage, or running multiple parallel cables.