The current that flows across the gap in air when contacts separate is called the ______.

The current that flows across the gap in air when contacts separate is called the ______.

• A. Arc
• B. Leakage
• C. Inrush
• D. Surge

Answer: (A)

When contacts separate under load, the voltage across the gap rises and the air can become ionized, forming a conductive plasma channel. That flowing current through the ionized air is called an arc. The arc keeps current flowing across the gap until the circuit is opened far enough or the current naturally goes to zero, at which point the arc can be quenched by the breaker’s design (arc runners, chutes, or insulating mediums). This arc behavior is different from leakage, which is a small, unwanted current that leaks through insulation when the circuit should be off; from inrush, which is a temporary, large current spike when a device is energized; and from surge, which is a transient overvoltage or overcurrent event—none of these describe the sustained conductive path formed by ionized air across the separating contacts.

When contacts separate under load, the voltage across the gap rises and the air can become ionized, forming a conductive plasma channel. That flowing current through the ionized air is called an arc. The arc keeps current flowing across the gap until the circuit is opened far enough or the current naturally goes to zero, at which point the arc can be quenched by the breaker’s design (arc runners, chutes, or insulating mediums).

This arc behavior is different from leakage, which is a small, unwanted current that leaks through insulation when the circuit should be off; from inrush, which is a temporary, large current spike when a device is energized; and from surge, which is a transient overvoltage or overcurrent event—none of these describe the sustained conductive path formed by ionized air across the separating contacts.