The size of an electric arc and destruction it can cause are directly proportional to the amount of ________ being interrupted.

• A. Voltage
• B. Current
• C. Resistance
• D. Capacitance

Answer: (B)

When a circuit is opened and current must continue to flow through the gap, an arc forms to carry that current. The hotter and more energetic the arc, the larger the arc and the more damage it can cause. The key factor that drives how big the arc gets and how destructive it is isn’t the system voltage or the device’s stored energy, but how much current is being interrupted. Higher current means more energy is dumped into the arc (P ≈ V_arc × I, with arc voltage roughly set by the gap and medium but the current scaling driving most of the energy), so the arc is hotter, wider, and lasts longer, eroding contacts and stressing equipment more. Capacity to interrupt that current safely is why current is the correct choice.