NFPA 855 (2026 Edition) — What’s New for Battery Energy Storage Systems

The 2026 edition of NFPA 855: Standard for the Installation of Stationary Energy Storage Systems has now been released, continuing the rapid evolution of safety requirements for battery energy storage systems (BESS). Since the first edition in 2020, each cycle has refined how the standard addresses emerging chemistries, larger system capacities, and lessons learned from real-world incidents.

For project teams, this edition is more than a simple “tune-up.” It broadens which technologies fall under NFPA 855, clarifies who is qualified to evaluate risk, and makes Hazard Mitigation Analysis (HMA) the default expectation for most ESS projects. It also raises the bar for emergency response planning and coordination with Authorities Having Jurisdiction (AHJs).

At Engineering Fire Protection, we’ve summarized below what we see as the most impactful changes, and what they mean for design, permitting, and operations.

1. Expanded Scope: More Chemistries Explicitly Covered

One of the first steps in applying NFPA 855 is confirming whether a system even falls within the scope of the standard. The 2026 edition significantly refines this step.

Reworked Table 1.3 and Added Chemistries

In earlier editions (2020/2023), Table 1.3 grouped established chemistries (such as lithium-ion, lead-acid, and flow batteries) and then applied a more conservative threshold to “other” battery technologies.

The 2026 edition restructures this table and explicitly lists a wider range of chemistries in alphabetical order, including, for example:

• Hybrid supercapacitors

• Iron-air and other aqueous systems

• Lithium metal

• Nickel-iron and nickel-hydrogen

• Sodium sulfur

• Zinc-air (aqueous), zinc bromide, and zinc manganese dioxide (Zn-MnO₂)

The thresholds in this table are based on nameplate capacity (maximum stored energy) rather than usable capacity—a detail that remains critical when determining applicability.

Why This Matters

By bringing more chemistries out of the generic “other” bucket and into the main table, NFPA 855:

• Reduces ambiguity when working with AHJs.

• Avoids defaulting to overly conservative “catch-all” requirements where clear, chemistry-specific thresholds now exist.

• Provides more flexibility for novel chemistries that are below the listed thresholds, especially when coordinating with jurisdictions also using IFC 2024, which drew heavily from the 2023 NFPA 855 thresholds.

2. Stronger Expectations for Qualified Professionals and Risk Assessment

The 2026 edition expands and refines key definitions in Chapter 3 to better align the standard with how complex BESS projects are actually evaluated.

Updated “Qualified Person” Definition

NFPA 855 now explicitly ties the “Qualified Person” definition to energy storage systems rather than just generic electrical equipment. The definition emphasizes that a qualified person must have:

• Skills, knowledge and training specifically related to ESS, and

• Safety training to recognize, avoid, and mitigate ESS hazards.

This is a meaningful shift from earlier editions, which focused more narrowly on electrical equipment and basic safety training.

Annex G and the Role of Fire Protection Engineers

Annex G – which provides guidance on risk assessments and performance-based approaches – has also been sharpened. In the 2026 edition, Annex G states that the risk assessment design process should be directed by a Registered Design Professional experienced in fire protection engineering and in energy storage risk assessment and plant operation for the type of facility considered.

In practical terms, this:

• Reinforces the expectation that fire protection engineers (FPEs) with ESS experience lead or direct HMAs and risk evaluations.

• Strengthens the technical credibility of submissions to AHJs by tying them to licensed professionals.

3. Hazard Mitigation Analysis (HMA): Now the Default Requirement

Perhaps the single biggest shift highlighted in the NFPA 855 (2026 Edition) treats Hazard Mitigation Analysis.

From Triggered Requirement to Baseline Expectation

In the 2020 and 2023 editions, an HMA was required only under certain conditions—for example, when installations exceeded the “maximum stored energy” limits of Chapter 9. If the installation stayed under those limits (but above the minimum chemistries/thresholds in the scope table), an HMA was not necessarily required.

The 2026 edition makes a decisive change:

• HMA is now the default requirement for virtually all ESS installations within the scope of NFPA 855, unless later chapters specify an exemption (such as for traditional lead-acid or aqueous nickel-based batteries, which have a long and well-characterized safety history).

• The prior “maximum stored energy” table in Chapter 9 has been removed, eliminating a common shortcut that allowed projects to bypass a formal HMA if they stayed under certain thresholds.

What an HMA Now Needs to Do

Given this shift, HMAs become the backbone of the design justification package. A robust HMA should:

• Describe thermal runaway initiation and propagation for the specific technology and configuration.

• Evaluate gas generation, dispersion, and potential deflagration or explosion hazards, referencing NFPA 68 and NFPA 69 where applicable.

• Address containment and separation strategies (e.g., spacing, barriers, or compartmentation).

• Explain how UL 9540A and any large-scale test data are used to support conclusions at the system or facility level.

Annex G provides structured guidance on risk evaluation formats and performance-based approaches, including tools like computational fluid dynamics (CFD), dispersion analysis, and consequence modelling.

From a project-management perspective, this means that budgets and schedules must now assume an HMA, unless a clear exemption in later chapters applies. Waiting until late in design to “add” an HMA is likely to be a schedule risk.

4. Fire Protection and Mitigation: Clarifying Strategy Choices

The broader NFPA 855 framework (as reflected in the recent editions including 2026) continues to clarify how fire control, fire suppression, and mitigation/controlled burn-out are treated.

For BESS projects, particularly outdoor containerized systems, acceptable strategies may include:

• Fire control – limiting fire spread to adjacent racks, containers, or exposures.

• Active suppression – using water-based or clean agent systems where effective and appropriate.

• Mitigation/controlled burn-out – allowing a damaged unit or container to burn within a controlled envelope while protecting people, adjacent equipment, and structures.

The increasing emphasis on HMA and performance-based risk assessment effectively forces clarity: if a project proposes to omit certain suppression systems in favour of separation, venting or controlled burn-out, that choice must be explicitly justified in the HMA and accepted by the AHJ.

Our recommendation: treat fire protection strategy and HMA as integrated workstreams, not separate checkboxes.

5. Emergency Response Planning and Training: New Section 4.3.3

The 2023 edition already required an Emergency Response Plan (ERP) and responder training, but details around timing and coordination were more diffuse. Section 4.3 in that edition outlined key topics (system information, shutdown procedures, contacts, etc.). 

The 2026 edition tightens this by adding a dedicated Section 4.3.3 that:

• Clarifies when and how the ERP must be established in the project timeline.

• Emphasizes coordination with AHJs and local fire service when developing and maintaining the plan.

• Lists minimum required contents of the ERP more explicitly, supporting a consistent baseline of information for responders. 

• From a practical standpoint, owners and operators should expect:

• More detailed pre-incident information sharing (system layout, chemistries, shutdown points, ventilation arrangements).

• Clearer documentation around roles, communications, and command structure during an incident.

• A stronger expectation that ongoing training and plan maintenance are part of operations, not one-time commissioning tasks.

At EFP, we often find that early joint sessions with the AHJ and the responding fire department are invaluable in aligning expectations, especially for first-of-a-kind projects in a jurisdiction.

Conclusion

The 2026 edition of NFPA 855 is a notable step in the maturation of energy storage safety standards. By expanding the scope of covered chemistries, elevating the role of qualified professionals, making HMA a default requirement, and sharpening expectations around emergency response planning, the standard provides a more consistent framework for managing ESS risk at scale.

Rather than prescribing one solution for all technologies, NFPA 855 (2026) expects data-driven, defensible design decisions—supported by testing, analysis, and documented risk assessment.

If you need support interpreting the 2026 edition for a specific project, developing an HMA, or preparing documentation for AHJ review, our team can help.

For code consulting and fire engineering design related to energy storage systems, please contact us at contact@engineeringfireprotection.com.