An arc flash can occur only if an arc exists between two points with a difference of ______.

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

Answer: (A)

An arc flash happens when there is a difference in electrical potential between two points large enough to ionize the air and create a conductive plasma arc. That potential difference, or voltage, is the key factor that initiates the arc. Without a voltage difference, there’s no arc to start, even if there’s current available. Once the arc exists, the current determines how intense and damaging it is, but the initiating condition is the potential difference. Resistance and capacitance describe how a circuit behaves, not whether an arc can form between two conductors. For air to break down and an arc to form, the voltage across the gap must exceed the air’s breakdown threshold, which depends on the gap distance.