During a routine inspection of a commercial building, an electrician measures 12 V AC between the metallic frame of a motor and a nearby grounded metal conduit. The motor is operating normally, and no overcurrent devices have tripped. What is the most likely cause of this voltage?

Question: During a routine inspection of a commercial building, an electrician measures 12 V AC between the metallic frame of a motor and a nearby grounded metal conduit. The motor is operating normally, and no overcurrent devices have tripped. What is the most likely cause of this voltage?

Answer options:

• A direct short circuit to the motor frame.
• An open circuit in the equipment grounding conductor for the motor.
• Normal inductive coupling between equipment and conduit. ✅ A high-impedance fault or induced voltage on the grounding system.

Correct answer: A high-impedance fault or induced voltage on the grounding system.

Explanation: A direct short circuit would likely cause overcurrent devices to trip. While normal inductive coupling can occur, 12 V indicates a more significant issue, such as a high-impedance fault, damaged insulation providing a leakage path, or induced voltage from parallel current paths, rather than a complete open circuit (which would show even higher or fluctuating voltage under a fault).