Explosion Control and Prevention Updates in the 2026 Edition of NFPA 855

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August 20, 2026 by Austin Smith, P.E.

The 2026 edition of NFPA 855, Standard for the Installation of Stationary Energy Storage Systems, refines and clarifies the standard’s approach to Explosion Control and Prevention, with a notable shift toward performance-based justification and clearer terminology. Throughout the chapter, language has been standardized to consistently reference “Explosion Control and Prevention,” improving alignment with NFPA 68, Standard on Explosion Protection by Deflagration Venting, and NFPA 69, Standard on Explosion Prevention Systems.

New Requirements for Energy Storage System Installations

Energy Storage Systems (ESS) that require explosion control and prevention must comply with NFPA 855 Section 9.7.6.7. This section introduces the following changes from the 2023 edition of NFPA 855:

  1. Clarifies that an explosion control and prevention system is required when the average vented gas concentration inside the ESS enclosure can accumulate beyond 25 percent of the Lower Flammability Limit (LFL),
  2. Acknowledges that localized gas pockets above 25 percent of the LFL likely exist inside the ESS enclosure and, therefore, a partial volume deflagration analysis must be conducted in accordance with NFPA 68.
  3. Requires that:
    1. Vented gases do not migrate between interconnected ESS enclosures, thereby limiting flame propagation and cascading events.
    2. The suitability of the NFPA 69 Explosion Control and Prevention system during a thermal runaway event should be demonstrated.
    3. An impact study of the logic used to determine the sequence of events for discharge when the ESS is equipped with a fire suppression system other than water must be submitted to the AHJ for approval.

While NFPA 68 explosion control systems were previously acceptable as a stand-alone explosion control method, an NFPA 69 Combustible Concentration Reduction System must also be provided for the ESS, resulting in greater resiliency and protection for the equipment, service personnel, and first responders.

Explosion Control & Prevention System Requirements

The Explosion Control and Prevention system is considered a critical safety system and must comply with emergency power supply, notification, commissioning, inspection, and testing requirements, including but not limited to:

  1. Compliance with NFPA 3, Standard for Commissioning of Fire Protection and Life Safety Systems (NFPA 855 Section 9.7.4.3) and NFPA 4, Standard for Integrated Fire Protection and Life Safety System Testing (NFPA 855 Section 9.7.4.2)
  2. Compliance with NFPA 110, Standard for Emergency and Standby Power Systems, or NFPA 111, Standard on Stored Electrical Energy Emergency and Standby Power Systems.
  3. Commissioning under the direction of a registered design professional,
  4. Confirm airflow against NFPA 69 evaluation reports.
  5. Undergo inspection & testing to confirm the systems operate as designed.

Key Takeaways & How Our Team Can Help

These updates to the 2026 edition of NFPA 855 collectively reinforce reliability and accountability in the implementation of explosion mitigation strategies.

Code Red Consultants helps owners, developers, designers, utilities, and AHJs navigate the evolving requirements associated with energy storage systems. Our team evaluates applicable code and fire protection requirements, identifies compliance challenges early, and supports practical solutions that align with project goals and regulatory expectations. Through technical expertise and experience across a wide range of ESS technologies, we help project teams manage risk and move projects forward with confidence.

Application of any information provided, for any use, is at the reader’s risk and without liability to Code Red Consultants. Code Red Consultants does not warrant the accuracy of any information contained in this blog as applicable codes and standards change over time. The application, enforcement and interpretation of codes and standards may vary between Authorities Having Jurisdiction and for this reason, registered design professionals should be consulted to determine the appropriate application of codes and standards to a specific scope of work.