How to Calculate Cable Cross-Section? A Comprehensive Guide for LED Lighting 2026

Why Is Cable Cross-Section Important?

Choosing the wrong cable cross-section leads to serious problems such as fire hazard, voltage drop, LED strip flickering, and premature failure.

Basic Concepts

• Cable cross-section (mm²): Larger cross-section = less resistance = less heating
• Voltage drop: A maximum of 3-5% is acceptable for LED strips
• Current (Amps): Watts ÷ Voltage

Calculation Formula

Cross-section (mm²) = (2 x L x I) ÷ (57 x ΔV)

• L: Cable length (meters)
• I: Current (Amps)
• 57: Copper conductivity coefficient
• ΔV: Permissible voltage drop

Ready Table (12V System)

Ready Table (24V System)

12V or 24V?

For long distances (5m+), prefer a 24V system!

Safety Rules

• ❌ Never use the minimum cross-section — choose the next size up
• ✅ Use a fuse — add a fuse to the transformer output
• ✅ Use NYY cable outdoors

FAQ

Which cable for LED strip?
Between 2x0.75mm² and 2x4mm² depending on power and length.

If the cable gets too hot?
The cable cross-section is insufficient. Use a thicker cable.

How to detect voltage drop?
If the LED strip is dimmer at the end compared to the beginning, there is a voltage drop.

Conclusion

• 🔧 Correct cable cross-section = safety + efficiency
• 📊 Perform the calculation, choose the next size up
• ⚡ For long distances, prefer a 24V system
• 🔥 Fuse is essential