Which voltages are used when calculating branch-circuit, feeder, or service loads?

The calculation of branch-circuit, feeder, or service loads is based on a variety of voltage levels that are commonly used in electrical systems. The correct answer encompasses a comprehensive range of voltages, including 120V, which is typically used for residential branch circuits; 240V, often used in larger residential and commercial applications; as well as 208Y/120 and 480Y/277, which are common in commercial settings. Other voltages like 347V and 600V also serve specific applications depending on the construction and design of the electrical systems.

Using a wide range is essential because different types of buildings and applications have different requirements for electrical loads. Therefore, when calculating loads, it is important to consider all relevant voltage levels, as outlined in the National Electrical Code (NEC). This ensures that electrical systems are designed to meet the necessary safety and efficiency standards.

The other responses are too restrictive or outdated, as they do not reflect the variety of voltages used in modern electrical installations. The correct answer provides an accurate representation of what is relevant for proper load calculation in accordance with NEC standards.