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NEC Quiz: Article 430 Answers, Part 6

by Mark Lamendola

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  1. Part VI of Article 430 provides the requirements for motor control circuits. Please note, this is distinct from requirements from motor controllers; those are in Part VII.

  2. You must provide separate overcurrent protection for the conductors in applications where the motor branch-circuit short-circuit and ground-fault protective device does not provide protection per 430.72(B)(2) [430.72(B)(1)].

  3. If the transformer supplies a Class 1 power-limited circuit, Class to, or class 3 remote-control circuit complying with Article 725. then protection must comply with Article 725 [ 430.72(C)(1)]. In all other cases except for control circuit transformers rated under 50VA (that are integrated with the controller) or with a primary less than 2A, protection is permitted to comply with Article 450 [430.72(C)(2)] .

  4. Control circuit transformers rated under 50VA (that are integrated with the controller) or with a primary less than 2A don't fall under Article 725 or Article 450. The former can be protected by primary OCPDs, impedance limiting means, or other inherent protective means [430.72(C)(3)] . If that transformer's primary is rated less than 2A, an OCPD rated or set at not more than 500% of the rated primary current can be used to protect the primary circuit [430.72(C)(4)].
  5. You would connect that transformer on the load side [430.75(B)].