MCB Selection & Trip Curve Calculator
Choose a preliminary MCB frame and trip-curve reference from load current, cable capacity, and fault-current inputs.
What this utility does
The MCB Selection & Trip Curve Calculator organizes continuous-load current, conductor coordination, B/C/D trip-curve behavior, and available breaking-capacity checks into one preliminary selection workflow.
How to use
- Enter the design load current and the cable or conductor capacity used for the circuit.
- Select the MCB rating and B, C, or D characteristic where the application requires it.
- Review the thermal coordination and prospective fault-current checks shown by the calculator.
- Confirm the final MCB against the manufacturer data, installation standard, ambient and grouping factors, and actual fault level.
Practical notes
- An MCB rating must not be selected from load current alone; conductor capacity, installation conditions, fault level, and the load starting characteristics also matter.
- B, C, and D curves have different instantaneous operating ranges, so the selected curve should match the actual load and manufacturer specification.
- Breaking capacity must be adequate for the prospective fault current at the installation point.