How do you compute main feederline circuit protection?

To compute main feeder line circuit protection, first determine the full load current (FLC) using the formula ( I = \frac{P}{\sqrt{3} \times V \times \text{PF}} ) for three-phase systems or ( I = \frac{P}{V \times \text{PF}} ) for single-phase systems, where ( P ) is the power in watts, ( V ) is the voltage, and PF is the power factor. Next, select a circuit breaker with a rating that exceeds the FLC but is appropriate for the conductor's ampacity and the system's short-circuit rating. Consider factors such as the type of load, potential inrush currents, and local codes or standards when finalizing the protection device. Ensure coordination with downstream devices to maintain system integrity.