Circuit breaker size calculator
A circuit breaker size calculator is a tool that helps determine the correct size of a circuit breaker for a given electrical circuit. Here's a simple calculator you can use:
Circuit Breaker Size Calculator
Enter the following values:
- Current Rating (A): The maximum current that the circuit is designed to carry.
- Voltage (V): The voltage of the circuit.
- Circuit Length (ft): The length of the circuit.
- Number of Conductors: The number of conductors (wires) in the circuit.
- Type of Load: The type of load the circuit is powering (e.g., lighting, motors, etc.).
Calculator Formula:
- Calculate the total current (I) in amperes using the formula:
I = (Power (W) / Voltage (V))
Where Power (W) is the total power required by the load.
- Calculate the circuit breaker size (CB) in amperes using the formula:
CB = I x 1.25 (for 120V circuits) or CB = I x 1.5 (for 240V circuits)
Example:
Suppose you have a circuit that powers a 1000W light fixture at 120V. You want to determine the correct size of a circuit breaker for this circuit.
Enter the values:
- Current Rating (A): 1000W / 120V = 8.33A
- Voltage (V): 120V
- Circuit Length (ft): 50 ft
- Number of Conductors: 2
- Type of Load: Lighting
Calculator Output:
CB = 8.33A x 1.25 = 10.42A
Recommended Circuit Breaker Size: 10A or 15A
Notes:
- The calculator assumes a 10% margin of error to account for variations in circuit conditions.
- The calculated circuit breaker size should be rounded up to the nearest standard size (e.g., 10A, 15A, 20A, etc.).
- Always consult local electrical codes and regulations for specific requirements.
- It's recommended to consult a licensed electrician if you're unsure about the calculation or the installation of the circuit breaker.