When refrigeration compressors are driven by conventional (nonhermetic) motors, the motors and controls are subject to the requirements in

When refrigeration compressors are driven by conventional (nonhermetic) motors, the motors and controls are subject to the requirements in

• A. NEC Article 440
• B. NEC Article 320
• C. NEC Article 500
• D. NEC Article 430

Answer: (D)

The key idea is that conventional, nonhermetic motors used to drive refrigeration compressors are treated as motor circuits with dedicated protection and control requirements. NEC Article 430 covers the electrical design of motor circuits: it specifies how conductors supplying the motor must be sized, the overcurrent protection and disconnecting means needed, and the types of motor controllers and starting methods that are permitted, along with motor overload protection. Because the motor in this setup is separate from the compressor (not hermetically sealed inside the unit), its electrical installation falls under these motor-circuit rules rather than under equipment-based rules. The other NEC articles don’t apply to this situation in the same way. Article 440 addresses air-conditioning and refrigeration equipment as installed units, typically when the motor is part of the equipment itself or when specific equipment requirements apply, such as hermetic or semi-hermetic configurations. The remaining articles cover topics like wiring methods for armored cable or locations with hazardous classifications, which aren’t the governing rules for motor circuits in this scenario.

The key idea is that conventional, nonhermetic motors used to drive refrigeration compressors are treated as motor circuits with dedicated protection and control requirements. NEC Article 430 covers the electrical design of motor circuits: it specifies how conductors supplying the motor must be sized, the overcurrent protection and disconnecting means needed, and the types of motor controllers and starting methods that are permitted, along with motor overload protection. Because the motor in this setup is separate from the compressor (not hermetically sealed inside the unit), its electrical installation falls under these motor-circuit rules rather than under equipment-based rules.

The other NEC articles don’t apply to this situation in the same way. Article 440 addresses air-conditioning and refrigeration equipment as installed units, typically when the motor is part of the equipment itself or when specific equipment requirements apply, such as hermetic or semi-hermetic configurations. The remaining articles cover topics like wiring methods for armored cable or locations with hazardous classifications, which aren’t the governing rules for motor circuits in this scenario.