How is a continuous load defined?

A continuous load is defined as one that operates for three hours or more at its maximum rating. This definition is important for ensuring that electrical systems are designed and rated appropriately to handle the sustained demand without risk of overheating or failure. In practice, understanding the characteristics of continuous loads helps engineers and electricians calculate the necessary capacity of wiring, breakers, and service equipment to ensure safe and efficient operation over time. This is crucial for load calculations and for maintaining the reliability of electrical systems.

The other choices do not correctly represent the definition of a continuous load. For instance, a load that operates for only two hours at maximum rating does not meet the three-hour minimum requirement, while loads that switch on and off periodically or operate only during peak demand times are typically classified differently, as they do not imply a sustained load over an extended period. Understanding this distinction is vital in the context of load calculations in electrical design.