Secondary protection for a transformer rated 600 volts or less must comply with which sections, as described in the material?

Secondary protection for a transformer rated 600 volts or less must comply with which sections, as described in the material?

• A. 240.21/ 408.36
• B. 240.21/ 408.35
• C. 240.20/ 408.36
• D. 240.22/ 408.37

Answer: (A)

Secondary protection for a transformer rated 600 volts or less is governed by selecting and coordinating the protective devices on the secondary side and how that protection is applied when the transformer is part of a panelboard arrangement. The rule set that applies here comes from two NEC provisions: one that covers branch-circuit overcurrent protection, and another that deals with protection for equipment installed in panelboards. The branch-circuit overcurrent protection section lays out how to size and place overcurrent devices for feeders and branch circuits feeding equipment like transformers, ensuring the conductors on the secondary side are protected from overcurrent and that the protection complements the transformer's rating. The panelboard-related section addresses how such equipment, when installed on or within a panelboard, is protected and coordinated with the panelboard arrangement, including ensuring the appropriate type and location of protective devices. Together, these two sections provide the complete guidance for protecting a low-voltage transformer secondary. The other section references in the choices cover different scenarios or details not specifically addressing both the secondary protection sizing and the panelboard installation coordination described here, so they don’t fit as the correct combination.

Secondary protection for a transformer rated 600 volts or less is governed by selecting and coordinating the protective devices on the secondary side and how that protection is applied when the transformer is part of a panelboard arrangement. The rule set that applies here comes from two NEC provisions: one that covers branch-circuit overcurrent protection, and another that deals with protection for equipment installed in panelboards.

The branch-circuit overcurrent protection section lays out how to size and place overcurrent devices for feeders and branch circuits feeding equipment like transformers, ensuring the conductors on the secondary side are protected from overcurrent and that the protection complements the transformer's rating. The panelboard-related section addresses how such equipment, when installed on or within a panelboard, is protected and coordinated with the panelboard arrangement, including ensuring the appropriate type and location of protective devices.

Together, these two sections provide the complete guidance for protecting a low-voltage transformer secondary. The other section references in the choices cover different scenarios or details not specifically addressing both the secondary protection sizing and the panelboard installation coordination described here, so they don’t fit as the correct combination.