A welder's machine connected to a 240 V single-phase circuit has exposed metal parts that have become energized due to an internal insulation failure. The equipment grounding conductor (EGC) for the circuit is severed. What protective device would be MOST likely to trip or operate in this scenario, even without a complete EGC path, assuming the fault current is high enough?

Question: A welder's machine connected to a 240 V single-phase circuit has exposed metal parts that have become energized due to an internal insulation failure. The equipment grounding conductor (EGC) for the circuit is severed. What protective device would be MOST likely to trip or operate in this scenario, even without a complete EGC path, assuming the fault current is high enough?

Answer options:

• A standard thermal-magnetic circuit breaker. ✅ A ground fault circuit interrupter (GFCI).
• A surge protective device (SPD).
• A residual current device with overcurrent protection (RCBO).

Correct answer: A ground fault circuit interrupter (GFCI).

Explanation: A GFCI detects imbalances in current between the live and neutral conductors, indicating a leakage current to ground. Even with a severed EGC, a person touching the energized metal could become the path to ground, causing the GFCI to trip. A standard breaker would only trip if the fault current directly returned to the source (phase-to-neutral or phase-to-ground via an intact EGC) at a high enough level.