When supplying a continuous load, the ampacity of a branch circuit or feeder must be at least what percentage of the continuous load?

When supplying a continuous load, the ampacity of a branch circuit or feeder is required to be at least 125 percent of the continuous load to ensure safe and effective operation. Continuous loads are defined as loads that are expected to run for three hours or more, which can lead to significant heating of conductors, connectors, and other equipment if not properly managed.

By specifying 125 percent, the code allows for a buffer that accounts for any potential variations in load and ensures that the conductors do not overheat and remain within safe operating temperatures under continuous use. This percentage takes into consideration the thermal effects of prolonged electrical consumption and helps maintain electrical safety and system reliability.

Providing ampacity based on a lower percentage, such as 100 percent or 110 percent, would not sufficiently mitigate the risks associated with continuous operation, potentially leading to overheating or equipment failure. The requirement for 125 percent helps promote best practices in electrical design for circuits handling continuous loads.