Feeder Size Calculator

Introduction: The Feeder Size Calculator is a handy tool designed for electrical engineers and professionals in the field of motor control. This article introduces the calculator, which simplifies the process of determining the appropriate feeder size for electrical motors based on power and voltage specifications.

Formula: The feeder size calculation involves a straightforward formula: dividing the motor power (in kilowatts) by the voltage (in volts). This calculation yields the recommended feeder size in amperes (A), ensuring the electrical system can adequately support the motor’s power requirements.

How to Use:

  1. Enter the motor power in kilowatts.
  2. Input the voltage in volts.
  3. Click the “Calculate” button to obtain the recommended feeder size.

Example: Consider a scenario where you have a motor with a power rating of 7 kW and operates at 220 V. Inputting these values into the calculator and clicking “Calculate” will provide you with the optimal feeder size necessary for the motor’s efficient operation.


  1. Why is feeder size important in electrical systems?
    • Feeder size ensures that the electrical system can supply the required current to motors without overloading or underperforming.
  2. Can I use the calculator for different units of power and voltage?
    • The calculator is designed to work with motor power in kilowatts and voltage in volts. Convert units if necessary before inputting values.
  3. What happens if the calculated feeder size is not a standard rating?
    • Round up to the nearest standard feeder size for practical application in electrical systems.
  4. Is this calculator suitable for both single-phase and three-phase motors?
    • Yes, the calculator is applicable to both single-phase and three-phase motors.
  5. Should I consider the motor’s efficiency in the calculation?
    • The calculator assumes ideal conditions. If motor efficiency is critical, adjust the motor power accordingly.
  6. What if I have multiple motors on the same feeder?
    • Calculate the total motor power and use it as input for the feeder size calculation.
  7. Can I use this calculator for DC motors?
    • The calculator is primarily designed for AC motors. For DC motors, consult specific guidelines or calculations.
  8. How does feeder size impact energy efficiency?
    • Proper feeder sizing ensures optimal performance, preventing energy losses and enhancing overall system efficiency.
  9. Is this calculator suitable for residential applications?
    • While designed for industrial use, the calculator can be adapted for residential applications with appropriate considerations.
  10. What should I do if I don’t know the motor’s power rating?
    • Refer to the motor’s technical specifications or consult with the manufacturer to obtain accurate power information.

Conclusion: The Feeder Size Calculator provides a quick and reliable solution for determining the appropriate feeder size for electrical motors. By simplifying the calculation process, it empowers engineers and professionals to make informed decisions, ensuring the efficiency and safety of electrical systems. Incorporate this tool into your workflow for seamless motor control applications.

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