Cable Sizing Calculator NF C 15-100

Free

Calculate cable cross-section and breaker rating based on power, length and allowable voltage drop.

Compliant with NF C 15-100

Circuit
W
m

0.85 default (motor), 1.0 for resistive

%

3% lighting, 5% other uses

🔧Sizing

🔌Cable section

2,5mm²

Breaker rating

16A

🔋Operating current Ib

15,3A

Actual voltage drop

Max allowable : 3%

2,4%

Iz admissible (selected section)

21A

Governing constraint

voltage drop
📐 NF C 15-100 Formulas
Ib = P / (U × cos φ) = 3000 / (230 × 0.85) = 15.3 A ΔU% = (2 × ρ × L × Ib × 100) / (S × U) Conditions : In ≥ Ib et In ≤ Iz

ρ copper at 70°C = 0.0225 Ω·mm²/m. The selected section is the maximum between the section by current-carrying capacity and the one by voltage drop.

Standards & regulations

  • NF C 15-100Low-voltage electrical installations — Rules
  • NF C 32-201Power cables — Current-carrying capacity calculation
  • UTE C 15-105Practical guide — Conductor section determination

This tool provides indicative estimates. Results do not substitute professional advice. Always verify with current regulations.

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