The National Fire Protection Association (NFPA) recently released a proposed Tentative Interim Amendment (TIA) to the 2020, 2023, and 2026 editions of the National Electrical Code (NEC). The TIA was submitted by Andrew Browne, Intertek, and has a comment closing date of October 30, 2026. 

TIA Log No.: 1949

Reference: 646.5 Informational Note, and Table A.1(2)

This TIA proposes the deletion of the informational note in Sec. 646.5. In the 2026 NEC, the informational note directs readers to UL Subject 2755, Outline of Investigation for Modular Data Centers, for information on listing requirements for MDCs. Additionally, the TIA wants to remove UL 2755 from Table A.1(2).

The substantiation for the proposal cites a press release from UL Solutions, “UL Solutions Withdraws Second Edition of UL 2755.” In the November 2025 release UL Standards & Engagement withdrew UL 2755:2018 from their available catalog of standards, stating, “its requirements, last updated in 2018, are now obsolete. They are out of alignment with current installation codes and standards, and do not adequately address safety concerns and code compliance for modern modular data centers.”

According to the TIA proposal, UL Solutions has developed a third edition of UL 2755 to update its standards, however this update is not yet publicly available. Because the 2^nd Edition contains safety issues and the 3^rd Edition is not available to the public, the TIA argues that the reference to the standard in NFPA 70 should be removed.

To read the TIA or submit a comment, visit NFPA’s website.