Arc flash incident energy is expressed in which of the following units?

Arc flash incident energy is measured in calories per square centimeter (cal/cm²). This unit quantifies the amount of thermal energy received by a surface exposed to an arc flash event. Understanding the energy in these terms is crucial for assessing the potential risk of burns and injuries to personnel working near electrical equipment.

Using calories as a measure allows for better correlation with the physiological effects on human skin since burn injuries can be categorized based on the number of calories that the skin receives from a thermal source. This standardization helps safety professionals establish effective safety protocols, protective equipment requirements, and compliance with regulations that aim to minimize the risk of electrical injuries in the workplace.

Other units mentioned, like joules or watts, relate to energy and power measurements, but they do not directly represent the thermal impact on skin in the context of arc flash incidents. Decibels, on the other hand, measure sound intensity and are irrelevant to the thermal energy concerns of arc flash scenarios. Thus, calories/cm² is the appropriate measurement for evaluating the hazards associated with arc flash incidents.