According to the NEC®, the ampacity of a feeder must be equal to or greater than what?

The ampacity of a feeder refers to the maximum amount of electrical current that it can safely carry. According to the National Electrical Code (NEC®), the ampacity must be equal to or greater than the calculated load after demand factors have been applied. This means that when determining the required size of a feeder conductor, it's important to consider not just the total maximum load it might experience but to apply demand factors to reflect realistic usage patterns. Demand factors allow for the understanding that not all circuits will be under full load simultaneously, which can significantly affect the sizing of feeders.

Using the calculated load after demand factors have been applied ensures that the system can handle the actual anticipated usage while maintaining safety margins. This approach takes into account both the operational efficiency of the system and safety concerns, ensuring that the feeder can adequately handle the loads without overheating or creating risks of failure. This basis for feeder sizing helps prevent over-sizing or under-sizing of conductors in real-world applications, which could lead to inefficiencies or dangerous conditions.