Overview

Enclosed panelboards boast higher short-circuit current ratings compared to standard panelboards. As a result, they require increased ventilation and greater separation between wiring and circuits. These distinctions mean that standard panelboards cannot be used interchangeably with enclosed panelboards in specific installations. NEC 2023 introduced a new Section 408.9 to specify replacement requirements for each type of panelboard separately. This addition aims to ensure compliance with the required protection standards for the respective panelboard type.

Applying the 2023 Code

Panelboards are designed to house circuit breakers and fuses for the individualized control of each downstream circuit; providing protection against overloads and faults, while serving as fundamental units in electrical distribution systems of commercial and residential buildings. Over time, panelboards can become damaged or outdated, leading to issues such as overloaded circuits, inadequate protection, and potential fire hazards. Thus, panelboard replacement becomes very crucial to ensure the safety, efficiency, and reliability of an electrical system. However, the two classifications of panelboards, simple and enclosed, both have different requirements for replacements. In previous editions of NEC, these differences in requirements were not presented, leading to confusion and malpractices. In NEC 2023, the replacement of both types of panelboards was listed separately and described in Section 408.9. The purpose of this new section is to ensure that when replacing panelboards, they comply with the essential protection standards specific to their type. This ensures that the replacements meet all required safety criteria for the respective panelboard type.

What’s New for the 2023 NEC?

The table below presents a comparison between the 2020 NEC and the 2023 NEC regarding Section 408.9.

2020 NEC

The NEC 2020 did not address the replacement of panelboards listed for enclosures and cabinets.

2023 NEC

408.9 Replacement Panelboards
Replacement panelboards shall be permitted to be installed in existing enclosures in accordance with 408.9(A) or (B).
(A) Panelboards Listed for the Specific Enclosure
If the replacement panelboard is listed for the specific enclosure identified by either catalog number or dimensional information, the panelboard shall be permitted to maintain its short-circuit current rating.
(B) Panelboards Not Listed for the Specific Enclosure
If the available fault current is greater than 10,000 amperes, the completed work shall be field labeled. If the available fault current is 10,000 amperes or less, the replacement panelboard shall be identified for the application. Any previously applied listing marks on the cabinet that pertain to the panelboard shall be removed.