Incident energy would be the highest for which of the following bus configurations?

Incident energy refers to the amount of thermal energy generated during an electrical fault, usually measured in calories per centimeter squared (cal/cm²). The bus configuration plays a critical role in determining the potential fault current and the subsequent incident energy resulting from an arc fault.

HCB (horizontally close bus) configurations are known for their ability to create higher fault currents due to their design, which minimizes the distance between energized conductors and has less impedance. This configuration, by virtue of its arrangement, facilitates a more concentrated fault current, leading to a faster and more intense arc-flash event when a fault occurs. The close proximity of the bus bars allows for more energy to be released in the form of thermal and radiant energy during a short circuit or arc flash scenario.

In contrast, other bus configurations, such as Type A, Type B, and Type C, are typically designed to either distance the conductors or configure them in a way that limits fault current to safer levels. These types do not provide the same level of energy concentration during a fault as the horizontally close bus configuration does, resulting in lower incident energy values.

Therefore, HCB configurations lead to the highest incident energy due to their structural characteristics that promote increased fault currents and more intense arc flash