Input Parameters
About This Calculator
- R = ρ × L / A
- 1φ: ΔV = 2 × I × R | 3φ: ΔV = √3 × I × R
- NEC recommends ≤3% branch, ≤5% total
How this voltage drop calculator works
Wire resistance: R = ρ × L / A where ρ(Cu)=0.0172, ρ(Al)=0.0282 Ω·mm²/m.
Voltage drop: ΔV = 2×I×R (single-phase) or ΔV = √3×I×R (three-phase). NEC recommends max 3% for branch circuits.
FAQ
Acceptable voltage drop?
≤3% branch, ≤5% total per NEC.
How to calculate?
ΔV = 2×I×R or √3×I×R for 3-phase.
How to reduce drop?
Larger wire, shorter run, or higher voltage.