What was the system voltage in the incident energy calculation example?

• A. 120 V
• B. 480 V
• C. 240 V
• D. 600 V

Answer: (B)

Understanding how system voltage affects incident energy calculations is essential because the available voltage drives the arcing current and the resulting energy. In this example, the system is a 480 V three-phase supply, so the line-to-line voltage used in the calculation is 480 V (the line-to-neutral would be 277 V, but for a bolted three-phase fault the calculation uses line-to-line). That’s why 480 V is the correct system voltage for the scenario. The other voltages represent different systems and would change the calculated incident energy.