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Electrical Formulas & Amp; Equations

  • Voltage = Watts / AMPS

Convert Watts to AMPS:

  • AMPS = Watts / Voltage (2,300 WATTS = 2300w divided by 120v = 19.1 AMPS)
  • for 3 Phase divide by 1.73

Convert AMPS to Watts:

  • Watts = Voltage x Amps (19.1 AMPS multiplied by 120v = 2300 Watts)
  • for 3 phase multiply by 1.73

Convert Horse Power to AMPS:

  • HORSEPOWER = (V x A x EFF)÷746
  • EFFICIENCY = (746 x HP)÷(V x A)
  • Multiply Horse Power by 746w (1 HP = 746 Watts)
  • Find Circuit Voltage and Phase
  • 30 HP at 480 (3 Phase) - 746 multiplied by 30 = 22380
  • 22380 divided by 480 (3 Phase) = 46.5
  • 46.5 divided by 1.73 = 29.5AMPS
  • Multiply all the motor loads by 1.50% and go to the next circuit size

Convert KVA to AMPS:

  • Multiply KVA by 1000/voltage
  • 30 KVA multiplied by 1000v = 30,000 Watts
  • 30,000 Watts divided by 480 = 62.5 AMPS
  • for 3 phase divide by 1.73

Convert KW to AMPS:

  • Multiply KW by 1000/voltage and then by power factor
  • 30KW multiplied by 1000v = 30,000
  • 30,000 divided by 480 = 62.5 x .90 = 56.25amps
  • for 3 phase divide by 1.73