Which is essential for protecting motor circuits?

• A. Use a switch with no overcurrent protection.
• B. Use an overcurrent protective device sized to the motor's full-load current.
• C. Use a GFCI as the sole protection.
• D. Use fuses without motor overload protection.

Answer: (B)

Protecting motor circuits relies on overcurrent protection that is properly sized to the motor’s full-load current. This ensures the protective device will not trip during normal startup or transient inrush, but will interrupt current if a short, stall, or overload occurs, safeguarding both the motor windings and the conductors feeding it. In addition, motors need motor overload protection (either built into the motor or as a separate device) to detect and shut off operation when the motor overheats from sustained overload.

The other options don’t provide the needed balance. A switch without overcurrent protection offers no safeguard against overload or short circuits. Relying on a GFCI alone protects only against ground faults and can nuisance-trip with motor startup or normal operation, not against overload. Fuses without motor overload protection may blow for faults but won’t reliably protect the motor from overheating due to a prolonged overload, so they don’t meet the protection requirements for motor circuits.