What two factors determine the heat exposure from an electrical arc?

The correct response highlights that the central factors influencing heat exposure from an electrical arc are distance and duration.

When an electrical arc occurs, it generates intense heat, which dissipates over distance. The proximity of a person or object to the arc significantly affects how much heat is experienced. As the distance increases, heat exposure decreases due to the dispersion of thermal energy into the surrounding environment.

Duration is another critical factor; the longer the exposure to the arc, the greater the potential for heat-related injuries. Extended contact with the heat generated by the arc increases the risk of burns and other injuries due to prolonged exposure.

Combining these two elements—distance and duration—provides a comprehensive understanding of how an electrical arc's heat exposure can impact safety. Factors such as voltage and length, current and resistance, or type and temperature do not encompass the immediate and practical risks associated with arc flash hazards in the way that distance and duration do.