Breaker Size Calculator: AC and DC Circuit Breaker Sizing Calculator

When it comes to designing circuits, selecting the right breaker size is not just a crucial task; it’s an art. Enter our Breaker Size Calculator, a user-friendly web tool designed to simplify and enhance the process of calculating breaker sizes for various scenarios, including DC, AC single-phase current, and AC three-phase current.

AC/DC Breaker Size Calculator

Type of Current

Type of Load Connected

Connected Load (watts)

Supply Voltage (volt) Line to Line Voltage of 3-Phase

Power Factor (0-1) Don’t Bother in case of DC

Minimum Breaker Size (amps)

Understanding the Breaker Size Calculator:

Our Breaker Size Calculator stands as a testament to the fusion of technology and precision engineering. It addresses the nuanced needs of different electrical systems, ensuring optimal safety and efficiency.

Circuit breaker sizing

Key Features of Breaker Sizing Calculator:

  1. DC Current Calculation:
    • Input Parameters: Load type, Load power in watts, Nominal voltage, and DC type.
    • Output: Instantaneous calculation of the minimum breaker size in amperes for DC circuits.
  2. AC Single Phase Current Calculation:
    • Input Parameters: Load type, Load power in watts, Nominal voltage, Power factor, and AC single-phase current type.
    • Output: Seamless determination of the minimum breaker size in amperes for AC single-phase circuits.
  3. AC Three Phase Current Calculation:
    • Input Parameters: Load type, Load power in watts, Nominal line-to-line voltage, Power factor, and AC three-phase current type.
    • Output: Accurate computation of the minimum breaker size in amperes for AC three-phase circuits.

Importance of Correct Breaker Sizing

  1. Firstly, it safeguards your electrical appliances and equipment. If a breaker is too large, it might not trip during a fault, putting your devices at risk. On the flip side, if it’s too small, it may trip unnecessarily, causing disruptions.
  2. Breakers are your frontline defense against overloads and short circuits. If they’re not appropriately sized, they may fail to trip in time, leading to overheating and, in extreme cases, fires.
  3. Proper breaker sizing contributes to the overall reliability of your electrical system. It helps prevent unnecessary downtime and disruptions, ensuring that your system operates smoothly without compromising safety.
3 phase circuit breaker sizing calculator

Circuit Breaker Calculation Formula

The breaker size calculation involves multiple factors, including the safety factor and power factor. The general formula for calculating the breaker size with these considerations is as follows:

$\text{Breaker Size Formula} = \frac{\text{Load Power} \times \sqrt{3}}{\text{Nominal Voltage} \times \text{Power Factor} \times \text{Safety Factor}}​​$

Here are the details of the parameters:

  • Load Power is the power consumed by the load in watts.
  • $\sqrt{3}$​ is the square root of 3, which accounts for three-phase systems only.
  • Nominal Voltage is the voltage supplied to the circuit.
  • Power FactorPower Factor is the power factor of the load, which can be a value between 0 and 1. Consider the Power Factor as 1 in the case of DC.
  • Safety Factor is the factor applied to the calculated value for additional safety margin based on load condition.

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