Voltage Regulation Calculator

Calculate line voltage regulation and power losses.

ANSI C84.1 Voltage Limits

Range Service Utilization
Range A (Normal)+/- 5%-8.3% to +4.2%
Range B (Emergency)+/- 5.8%-11.7% to +5.8%

Regulation Formula

VR% = (Vs - Vr) / Vr × 100

Vdrop = I × (R×cosθ + X×sinθ)

Voltage Regulation Guidelines

Typical Limits

  • NEC branch circuits: 3% max
  • NEC feeders: 2% recommended
  • Combined: 5% total max
  • Motor circuits: 3% (NEC 430.6)
  • Sensitive equipment: 2%

Improvement Methods

  • Increase conductor size
  • Use parallel conductors
  • Reduce line length
  • Improve power factor
  • Add voltage regulators