What percentage of the continuous load must be added to the noncontinuous load for overcurrent protection of branch circuits?

The correct answer is that 125% of the continuous load must be added to the noncontinuous load when calculating for overcurrent protection of branch circuits. This requirement is guided by the National Electrical Code (NEC), which establishes safety standards for the electrical installation and ensures that circuits are protected against overloads.

Continuous loads are defined as loads where the maximum current is expected to continue for three hours or more, and since they are sustained for an extended period, additional capacity is needed to handle both these loads and any noncontinuous loads without tripping the circuit breakers. The NEC specifies the need to apply an additional 25% to the continuous load to promote safe operation and prevent nuisance tripping, thus ensuring that the system can handle potential variations in current draw without exceeding the safe limits.

By applying this 125% rule, circuit designers can account for factors like heat generation and materials' thermal properties. This ensures better reliability of the electrical system in real-life operating conditions. This understanding is crucial for anyone preparing for the Limited Energy License as it emphasizes safe and compliant design practices in electrical engineering.