July 9, 2024

Informational Bulletin on the UL 9540 Safety Standard and the UL 9540A Test Method

This SEAC document provide a high-level overview of the Safety Standard “ANSI/CAN/UL 9540 Energy Storage Systems and Equipment” and the UL thermal runaway fire propagation test method “ANSI/CAN/UL 9540A Test Method for Evaluating Thermal Runaway Fire Propagation in Battery Energy Storage Systems” (BESS).

The Sustainable Energy Action Committee’s (SEAC) Energy Storage Systems (ESS) Standards Working Group has developed this informational bulletin to provide a high-level overview of the Safety Standard “ANSI/CAN/UL 9540 Energy Storage Systems and Equipment” and the UL thermal runaway fire propagation test method “ANSI/CAN/UL 9540A Test Method for Evaluating Thermal Runaway Fire Propagation in Battery Energy Storage Systems” (BESS).

UL 9540A is a “Test Method” used to characterize the internal thermal runaway and fire propagation performance of a BESS as required in accordance with applicable fire codes and UL 9540. UL 9540A is NOT a certification standard, therefore there is no “listing” that results from performing UL 9540A testing. 

SEAC published this version of the informational bulletin on July 9, 2024. SEAC will update the document as needed based on new developments affecting UL 9540 and UL 9540A.

This document addresses: 

  • UL 9540 System Certification Fundamentals
  • UL 9540A Fire Test Levels – Terminology and Descriptions
  • The origins and key elements of UL 9540 and UL 9540A
  • The essential differences between UL 9540 and UL 9540A

This material is based upon work supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) under the Solar Energy and Technologies Office Award Number DE-EE0009001.0000. The views expressed herein do not necessarily represent the views of the U.S. Department of Energy or the United States Government.