How is arc flash incident energy typically expressed?

Arc flash incident energy is typically expressed in calories per square centimeter (cal/cm²). This unit of measurement provides a quantifiable indication of the thermal energy that a person could be exposed to during an arc flash event. It is essential for determining the level of personal protective equipment (PPE) required to safely work in areas where arc flash hazards exist.

The concept behind using calories per square centimeter is grounded in understanding how much heat energy could potentially be transferred to a person’s skin during an incident. This helps in implementing safety measures and training programs aimed at arc flash awareness and prevention.

The other options are based on different electrical and thermal phenomena but do not measure incident energy in the context of arc flash. Joules/cm², while it represents energy density, is less commonly used in the industry compared to calories. Volts/cm² refers to electric field strength, and Watts/cm² represents power per unit area. Neither of these units accurately reflects the thermal impact of an arc flash event on human tissues as well as calories per square centimeter does.