How does the NEC define a continuous load?

The definition of a continuous load in the National Electrical Code (NEC) refers to a load that is expected to run for three hours or more. This understanding is crucial in electrical design and load calculations, as it helps ensure that circuits and equipment are adequately rated to handle the demand over extended periods.

When determining the capacity of electrical circuits, it is vital to account for continuous loads because they require additional considerations for safety and efficiency. For instance, when sizing conductors and overcurrent protection devices, engineers apply a derating factor to avoid overheating and ensure that the electrical system can operate safely under prolonged usage.

Understanding the duration aspect of continuous loads helps differentiate them from other types of loads that may only operate intermittently or for short durations, which might not necessitate the same level of capacity or precautions in electrical design.