How do you determine the total calculated feeder load with noncontinuous and continuous loads?

To determine the total calculated feeder load with noncontinuous and continuous loads, the correct approach involves recognizing how each type of load is treated differently due to their operational characteristics. Noncontinuous loads are those that do not operate continuously for three hours or more, while continuous loads remain operational for three hours or more.

The methodology for calculation is based on the National Electrical Code (NEC), which stipulates that for feeders, the total load calculation should sum 100% of the noncontinuous loads and 125% of the continuous loads. This adjustment for continuous loads is necessary because they can contribute to the total load in a more significant way over extended periods. By applying a 25% increase to the continuous loads, the calculation provides a buffer that accounts for their sustained operation, ensuring that the feeder system is adequately rated to handle the potential maximum load without risk of overload.

This method helps ensure safety and reliability in the electrical system by correctly sizing feeders to handle the anticipated load during normal operations, including peak usage periods. Thus, adding 100% of noncontinuous loads to 125% of continuous loads results in an accurate total calculated feeder load.