TIA Proposed for 2023 NEC Regarding Short-Circuit Current Rating

The National Fire Protection Association (NFPA) recently released a proposed Tentative Interim Amendment (TIA) to the 2023 Edition of the National Electrical Code (NEC). The TIA was submitted by Ronnie Ridgeway, Siemens, and has a comment closing date of April 20, 2023.

TIA Log No.: 1699

Reference: 408.6

1. Revise 408.6 to read as follows:

408.6 Short-Circuit Current Rating. Switchboards, switchgear, and panelboards shall have a shortcircuit current rating not less than the available fault current. In other than one- and two-family dwelling units, the available fault current and the date the calculation was performed shall be field marked on the enclosure at the point of supply. The marking shall be of sufficient durability to withstand the environment involved. comply with 110.21(B)(3).    

Substantiation: For NFPA 70 2023 the wording in NFPA 2020 110.21(B)(3) was combined with some of the wording in NFPA 70 2020 110.21(B)(1). 110.21(B)(3) does not exist in NFPA 70 2023 but the required wording is a part of 110.21(B)(1). This change adds the required wording from NFPA 2020 to 408.6 and removes the reference to 110.21(B)(3).

Emergency Nature:  The standard contains an error or an omission that was overlooked during the regular revision process. The proposed TIA intends to correct a circumstance in which the revised NFPA Standard has resulted in an adverse impact on a product or method that was inadvertently overlooked in the total revision process or was without adequate technical (safety) justification for the action.

The standard contains an error that was overlooked during the regular revision process. This TIA corrects the error by removing a technical requirement regarding the marking that was not intended or required.

For more information or to read the full proposed TIA, visit NFPA's website.