Overview

Panelboards and their enclosures undergo separate testing and evaluation before being assembled in the field to meet specific application requirements. According to Section 408.38 of the NEC, panelboards must typically be installed in dead-front cabinets or enclosures, with exceptions permitted for other types accessible only to qualified personnel. In the 2023 edition, Section 408.38 was updated to include specific criteria for evaluating and installing panelboards and their enclosures. Now, panelboard and enclosure combinations require evaluation for applications where fault currents exceed 10,000 amps.

Applying the 2023 Code

Panelboard enclosures serve as protective housings designed to maintain the safety and functionality of electrical panelboards by preventing accidental contact with live parts and containing arcs or sparks during operation. Traditionally, panelboards and enclosures undergo separate testing and are provided as separate components. However, they can also be integrated into a single unit known as an enclosed panelboard, which undergoes comprehensive testing as a whole.

In previous NEC versions, Section 408.38 outlined guidelines for selecting panelboard enclosures, requiring panelboards to be mounted in dead-front cabinets, cutout boxes, or identified enclosures. An exception allowed the use of non-dead-front, externally operable panelboards if accessible only to qualified personnel. However, this section did not specify criteria for evaluating enclosed panelboards, potentially resulting in inconsistent installation practices. To rectify this issue, the 2023 NEC introduced new requirements. Under the updated guidelines, if the available fault current exceeds 10,000 amps, the panelboard and enclosure combination must undergo evaluation for the application, rather than just the panelboard itself. This update aims to standardize the use of enclosed panelboards and ensure they meet rigorous safety and performance standards.

What’s New for the 2023 NEC?

The comparison of 2020 NEC and 2023 NEC in terms of Section 408.38 is given in the Table below.