IEC 60364-5-52
NEC 310.16
GB 16895
Voltage-drop check
Cable size calculator
Professional wire cross-section sizing by current or power — IEC, NEC (USA) and GB (China) standards, with voltage-drop check and ready-to-order cable options.
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Recommended conductor
Enter a value to see the recommendation.
Installation method
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Cable options
Nearest standard size that carries the load with your installation conditions and stays within the voltage-drop limit.
| Size | Ampacity | V-drop | Status |
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How the sizing works
1 · Load current
From power the current is Ib = P / (V · cos φ) for single-phase, or Ib = P / (√3 · V · cos φ) for three-phase. Enter current directly to skip this step.
2 · Correction factors
The table ampacity of every size is corrected for installation method, ambient temperature and grouping. A conductor is valid only when its corrected ampacity is at least the design current.
3 · Voltage drop
Drop is ΔU = k · I · L · ρ / S (k = 2 single-phase, √3 three-phase; ρ = 0.0175 Ω·mm²/m copper, 0.0282 aluminium). If a size exceeds your limit it is rejected even when its ampacity is enough.
4 · Recommendation
The smallest size passing both checks is recommended; nearby sizes are listed as alternatives, with the closest equivalent shown in the other standards.
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Important
This tool gives a fast engineering estimate for typical PVC/XLPE insulated cables. Correction factors are simplified. Final conductor and protective-device selection must follow the full local wiring code (IEC 60364, NEC/NFPA 70, GB 50054, etc.) and, where required, be approved by a qualified electrical engineer.