In what scenario must a motor's full load current be increased by 125% for feeder circuit calculations?

The reason for increasing a motor's full load current by 125% in the context of feeder circuit calculations is based on the requirement to ensure adequate capacity for starting currents and future loads. This adjustment is necessary when connecting the largest motor with any additional motors. The starting current of motors can be significantly higher than their full load current, and by increasing the current rating to 125%, the circuit design can accommodate these inrush currents and ensure that the feeder and service conductors are sized appropriately to handle the total load safely.

When the largest motor is connected alongside another motor, this practice helps prevent under-sizing of the conductors, which might lead to overheating or tripping of protective devices during startup conditions. Therefore, it is essential to account for this increased demand in the feeder circuit calculations to maintain system reliability and safety.