⚠️ HVAC capacitors are typically rated **370–440 V** (some start capacitors up to 600 V). Live voltage at the terminals can exceed 300 V — extreme shock hazard.

Capacitor Test Under Load (Volts/Amps)







Show Formula & Explanation

Formula: µF = (2652 × Amps) ÷ Volts (at 60 Hz)

  • Amps: Clamp the start winding lead between capacitor and motor
  • Volts: Measure across the capacitor terminals while running
  • Rated Capacitance: The value printed on the capacitor’s label (e.g., “10 µF ±6%”). This is the manufacturer’s specification for what the capacitor should measure when new.
  • Compare: The calculated value should be within ±5% of the rated capacitance

Formula: µF = (2652 × Amps) ÷ Volts (at 60 Hz)

  • Amps: Clamp the start winding lead between capacitor and motor
  • Volts: Measure across the capacitor terminals while running
  • Rated Capacitance: The value printed on the capacitor’s label (e.g., “10 µF ±6%”). This is the manufacturer’s specification for what the capacitor should measure when new.
  • Compare: The calculated value should be within ±5% of the rated capacitance