When computing motor loads, what percentage of the motor full-load current rating must be used for a single motor in a building?

When computing motor loads for a single motor, it is important to consider the full-load current rating of the motor. Using 125% of the motor's full-load current rating as a standard is essential for ensuring that there is adequate capacity for starting currents, which are typically higher than the running currents.

This 125% rule is part of the National Electrical Code (NEC) guidelines, which aim to prevent overheating and potential burnout of the motor due to inrush currents when the motor starts. By accounting for this additional 25%, you help ensure the motor operates safely under variable load conditions and reduces the risk of tripping circuit breakers or causing damage to the electrical components.

This percentage also provides a margin of safety for factors such as voltage drops and potential increases in load, allowing the electrical system to handle unexpected surges in demand without compromising performance. Thus, using 125% of the full-load current rating is the accepted standard for calculating the motor load in a building's electrical design.