NFPA 855 Changes in the 2026 Edition

NFPA 855 Changes in the 2026 Edition 

As the renewable energy sector continues to grow, so does the importance of ensuring the safety of energy storage systems (ESS). The newly released 2026 edition of NFPA 855: Standard for the Installation of Stationary Energy Storage Systems brings several critical updates that will affect how we manage risk, design systems, and plan for emergencies. Here’s what every H&S professional needs to know.

Since its first edition in 2020, NFPA 855 has become the benchmark for safely deploying batteries in homes, businesses, and utility-scale projects. It’s still a young, standalone standard, but each edition has brought meaningful refinements, and 2026 is no exception.

2023 Edition

In the 2023 edition, initiation was limited to air-aspirating smoke detection or radiant-energy detection. In the first draft of the 2026 edition, the committee clarified the intent: “There is a need to correlate the detection technologies with NFPA 72. Specifying ‘air-aspirating’ as the method of smoke detection was inappropriate; other forms of smoke detection can be utilized based on the conditions present at the location.”

Under the earlier edition, if only a portion of an existing facility were newly designated to store lithium-ion batteries, then, even if the building already had detection and notification systems, an additional radiant-energy or air-aspirating detector would have been required. The 2026 edition changes that approach by aligning with the National Fire Alarm and Signaling Code (NFPA 72) and allowing the use of other suitable smoke-detection technologies. However, it’s important to note that the IFC 2024 still uses the 2023 edition of NFPA 855 language. As many jurisdictions are only now adopting the 2024 I-Codes, be aware of local amendments that may update 2023 wording to reflect the 2026 edition.

Also, UL Standard 2684, Video and Thermal Image Detectors for Fire Alarm Systems, was most recently revised in August 2025. While many products are still in the process of obtaining listings, expect more off-the-shelf solutions to be listed to UL 2684 as the market catches up.

·        2023 edition, section 14.3.2.1.2 – “The rooms or spaces shall be provided with a fire alarm system activated by an air-aspirating smoke detector system or a radiant-energy detection system with occupant notification installed in accordance with NFPA 72.”

·        2026 edition, section 14.3.2.1.2 – “The rooms or spaces shall be provided with a fire alarm system activated by a smoke detector system, a thermal image fire detection system, or a radiant-energy detection system with occupant notification installed in accordance with NFPA 72.”

New & Emerging Technologies More Explicitly Covered

The first step when using NFPA 855 is to review the scope. The standard applies only to certain kilowatt-hour (kWh) ratings by battery technology. Where energy ratings are small (which limits energy density), code requirements might not apply. For example, a small server room in a business-occupancy building or a battery backup for a small carbon-dioxide (CO₂) skid might be <20 kWh for lithium-ion chemistry and <70 kWh for valve-regulated lead-acid (VRLA) batteries.

The 2023 edition Table 1.3 subdivides battery technologies and capacitor energy storage systems. However, the 2026 edition does not segregate them; instead, it lists more battery chemistries in simple alphabetical order, with the threshold for other battery technologies at the bottom. Keep in mind, the values mentioned in Table 1.3, is the nameplate capacity or maximum stored energy, not the usable capacity. Chapter 1 & tech-specific tables in Chapter 9 have been updated. 

NFPA 855: 2023 Edition	NFPA 855: 2026 Edition
Focus on established chemistries; Conservative threshold for “other.”	The code names new chemistries explicitly; other listed chemistry thresholds remain the same.
Included Lead-acid, Ni-Cad, Ni-MH & Ni-Zn, Lithium-ion, Sodium nickel chloride, flow batteries, flywheel ESS, and electrochemical double-layer capacitors.	Added Hybrid supercapacitors, Iron-air, aqueous, Lithium metal, Ni-Fe, Nickel-hydrogen, Sodium sulfur, Zinc-air, aqueous, Zinc bromide, and Zinc manganese dioxide (Zn-MnO2).

Although the 2024 edition of the International Fire Code (IFC 2024) adopts many thresholds from NFPA 855 (2023), facilities using a listed chemistry that exceeds the old “other battery technologies” threshold, but remains below the listed chemistries under the 2026 edition, may have flexibility when working with the Authority Having Jurisdiction (AHJ). Remember: early communication with the AHJ is crucial.

Clearer Definitions

The 2026 edition expands Chapter 3 definitions to reduce ambiguity, defining commonly used terms, including Fire Risk Assessment and Registered Design Professional.

The 2026 edition also updated the Qualified Person to list knowledge and training related to specific energy storage systems:

·        2023 edition: “Qualified Person – One who has skills and knowledge related to the construction and operation of the electrical equipment and installations and has received safety training to recognize and avoid the hazards involved.”

·        2026 edition: “Qualified Person – One who has skills, knowledge, and training related to the construction and operation of energy storage systems and electrical equipment and installations and has received safety training to recognize, avoid, and mitigate the hazards”

This matters because the code clarifies the qualifications for individuals performing consulting operations and risk assessments.

Annex G in the 2026 version follows with: “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 of the type of, or similar to the plant under consideration.” The 2023 edition referred to “parties” rather than a registered design professional (PE).

Hazard Mitigation Analysis (HMA): From Optional to Required

Chapter 4 in the 2026 version introduces significant changes, now making Hazard Mitigation Analysis the default. Chapter 9 removed the “Maximum Stored Energy” table.

One of the most significant changes in NFPA 855 (2026) is its approach to HMA—a formal safety risk assessment for an energy storage installation.

NFPA 855: 2023 Edition	NFPA 855: 2026 Edition
Code only required an HMA in some instances.	HMA is the default requirement for virtually all ESS installations under the scope of the code, unless modified in later chapters.

For example, per Section 9.3.2, an HMA is not required for lead-acid and aqueous nickel-based battery ESS. This reflects that traditional lead-acid and nickel-cadmium systems, whose risks are better characterized, with a long history with these chemistries, may not always require an HMA by default.

Previously (in the 2020/2023 editions), facility owners only had to conduct an HMA if their project triggered specific criteria. For example, if owners wanted to install more energy storage than the maximum allowed in Chapter 9, they could do so after the approval and performance of an HMA. If the project in question stayed under those limits (and above the threshold quantities in Chapter 1 for the given battery chemistry), no HMA was necessary. In practice, this meant modest-sized installations often avoided a hazard mitigation analysis under the old rules.

Improved Emergency Response Planning and Training

In the 2023 edition, the code called for emergency planning and training in Section 4.3. The plan details multiple requirements, for example, first-responder information, system layout, shutdown procedures, and responsible contacts. The new edition adds when and how to establish this plan and coordinate with the AHJ.

A new Section 4.3.3 covers the ERP (Emergency response plan) and training. The code lists the minimum requirements for the plan explicitly. The response plan should address minimum, mitigation, preparedness, response, and recovery. The new edition also requires the emergency operations plan to be reviewed annually, with a refresher training conducted annually, and emergency responders notified of the training dates and locations.

Fire Control & Suppression

Sprinkler requirements under NFPA 13 (or equivalent) remain in place. In the 2023 edition, Section 4.9.3 focused on “alternate fire protection systems,” with applicability based on fire and explosion testing. The new 2026 edition reframes this as “automatic fire control;” the “alternate” label is removed, and NFPA 13 is now included within a broader section on automatic fire control and suppression standards.

Emergency Power Supply Systems

A new Section 4.10 addresses Emergency Power Supply Systems (EPSS) and Stored Emergency Power Supply Systems (SEPSS):

·        Critical safety systems that rely on power must be provided with reliable EPSS or SEPSS power in accordance with NFPA 110 or NFPA 111.

Per Section 4.10.22, the design for the EPSS should be available to the Fire Protection Engineer (FPE) of record and the AHJ for review and approval.

Stricter Fire Testing Requirements: UL 9540A + Large-Scale Fire Tests

A notable change in NFPA 855 (2026) is the strengthening of fire and explosion testing for ESS. In light of recent battery fires, the code ensures system testing under realistic worst-case conditions, not just lab-scale scenarios. NFPA 855 (2026) now explicitly requires large-scale fire testing (LSFT) in conjunction with Underwriters Laboratories (UL) 9540A testing, demonstrating that systems can withstand and contain severe thermal runaway events.

UL9540A is the Test Method for Battery Energy Storage Systems (BESS), which is a protocol for testing ESS, initiates thermal runaway at the cell, module, unit, and installation levels of an ESS product, and collects the resulting data to help evaluate the fire and explosion hazards. However, as currently written, if a product passes at a given level, the test concludes and does not have to proceed to the next level. The argument against stopping the test is that the data collected may not present a realistic fire scenario, and therefore cannot truly be considered “large-scale”.

UL 9540A (a UL test method) forces thermal runaway at the cell, then module, unit, and installation levels, collecting data at each stage. However, UL 9540A can conclude early if a level passes (e.g., no module propagation), meaning some large systems would have never been tested as a whole. The 2026 edition addresses this gap.

The old Section 9.1.5 (Fire and Explosion Testing) has been moved to a new Section 9.2. Now, per Section 9.2.1.2:

·        Where cell thermal runaway releases flammable gases during a cell- or module-level test, an additional unit-level test should be conducted involving intentional ignition of vent gases to assess fire/deflagration hazards; and

·        The large-scale fire testing required should be conducted or witnessed and reported by an approved testing laboratory, which will characterize the gas composition and demonstrate that a fire involving one ESS unit will not propagate to an adjacent unit.

Technology-Specific Requirements and Thermal Runaway Propagation Prevention (TRPP) Systems

NFPA 855 (2026) expands the technology-specific requirements in Chapter 9 to include the new chemistries. Also, Section 9.7.6.6 now addresses Thermal Runaway Propagation Prevention (TRPP) systems. Compliance with ASME B31.1 or ASME B31.3 (as applicable) should be documented as part of the UL 9540 listing. These systems are an active, automatic system for ESS that detects precursors to cell thermal runaway (e.g., off-gas or abnormal temperature) and actuates a targeted suppression/cooling medium to absorb heat and stop propagation to adjacent cells, modules, or racks. Passive features (barriers, spacing, enclosures) are complementary but do not, by themselves, constitute TRPP.

Storage of Lithium Metal or Lithium-Ion Batteries

While Chapter 14 (storage of Li-ion or Lithium-Metal batteries) did not change significantly, there are notable updates.

The fire detection section has been reworded to allow for a smoke detector system, a thermal-image fire detection system, or a radiant-energy detection system (previously: air-aspirating smoke detection or radiant-energy detection only). Additionally, outdoor storage language is aligned to include thermal-image detection along with radiant-energy detection.

NFPA 855: 2023 Edition	NFPA 855: 2026 Edition
Required to provide fire detection in the battery storage areas using either air-aspirating or radiant-energy technologies. Didn’t explicitly mention thermal-imaging detection, even though the basic working principle in this technology comes under radiant-energy-based.	Section is reworded to initiation using “smoke detection.” Explicit use of “air-aspirating” is removed. Explicitly adds “Thermal image fire detection”. A new section provides an exception for the temporary storage of batteries at SoC 50% or less at the installation locations.

2026 Edition

A new section, 14.1.3, allows batteries, modules, and ESS temporarily staged or stored at an installation site to not comply with Chapter 14 when the state of charge (SOC) ≤ 50% and subject to other conditions.

Frequently Asked Questions (FAQ)

A.   What is NFPA 855?

NFPA 855 is the standard for the installation of stationary energy storage systems (ESS). It establishes safety requirements for the deployment of batteries in homes, businesses, and utility-scale projects.

B.   What are the biggest changes in the 2026 edition of NFPA 855?

The 2026 edition expands the scope to cover more battery chemistries, makes Hazard Mitigation Analysis (HMA) the default, strengthens professional qualifications, requires stricter fire testing, and adds new guidelines for emergency planning, EPSS/SEPSS, TRPP systems, and lithium battery storage.

C.   How can companies prepare for compliance with NFPA 855 (2026)?

Companies should plan for a required HMA, coordinate early with the AHJ. This ensures that detection, suppression, and testing meet the new code language. Involvement of a licensed PE is crucial to compliance.

D.   How do TRPP systems improve safety?

The code now addresses Thermal Runaway Propagation Prevention (TRPP) systems and requirements. They are an active system that prevents a failure in one cell or module from spreading to others. This reduces the chance of large-scale fires.

E.   Do I always need to perform a Hazard Mitigation Analysis under NFPA 855 (2026)?

Yes, a Hazard Mitigation Analysis (HMA) is now the default requirement for most ESS installations. Limited exceptions exist for lead-acid and aqueous nickel-based systems, whose risks are already well understood.

F.    How does the 2026 edition impact lithium-ion battery storage?

It broadens acceptable fire detection methods, allowing broader smoke detection and thermal imaging in addition to radiant-energy detection. It also provides flexibility for temporary storage when the state of charge is ≤50% under specific conditions.

G.   How will the changes to NFPA 855 affect project timelines and costs?

Most projects will now need to budget for a formal HMA, expanded testing, and annual emergency response training. While this adds requirements, it supports smoother approvals with AHJs and safer long-term operation.

H.   Who qualifies to perform risk assessments under NFPA 855 (2026)?

Risk assessments must be led by a registered design professional, typically a licensed PE with fire protection and ESS experience. This change clarifies that general consultants or “parties” no longer meet the requirement.

I.    What do the new testing requirements mean for manufacturers?

Manufacturers must now provide both UL 9540A and large-scale fire test results. These tests confirm systems can withstand thermal runaway and prevent fire propagation to adjacent units.

J.    What are the current installation codes and standard requirements for ESS in the US related to fire and explosion testing?

The 2023 edition of NFPA 855 and the 2024 edition of the International Fire Code require fire and explosion testing to be conducted in certain situations. Both editions reference that such testing shall be conducted on a representative ESS in accordance with UL 9540A, the Standard for Test Method for Evaluating Thermal Runaway Fire Propagation in Battery Energy Storage Systems.

K.   What fire and explosion test method will the 2026 edition of NFPA 855 specify?

UL Solutions experts, fire officials and industry stakeholders are actively drafting stricter fire and explosion testing protocols in the upcoming 2026 edition of NFPA 855. The current draft specifies that fire testing must be conducted in accordance with UL 9540A and, in certain instances, incorporate large-scale fire testing.

L.    Will UL 9540A address large-scale fire testing after the release of the 2026 edition of NFPA 855?

UL 9540A will evolve during the coming months to address large-scale fire testing criteria in NFPA 855.  A dedicated task group within the UL 9540A Technical Committee has been diligently working the last year on development of a test method to address the increased demand for robust fire and explosion testing scenarios.

M.  Can test methods other than UL 9540A be used for ESS large scale fire and explosion testing?

The current and next edition of NFPA 855 specify that UL 9540A is the required test method for ESS installation. In certain instances, ESS installations may require additional large-scale testing. Organizations may turn to alternative test methods for large-scale testing. However, these test methods are not widely accepted and should be considered on a case-by-case basis. 

N.   Where can UL Solutions conduct large-scale fire testing?

UL Solutions offers large-scale fire testing out of several facilities in the US, China and Korea.

Large batteries present unique safety considerations, because they contain high levels of energy. We remain committed to helping battery innovators enhance energy storage capacity with services to support greater safety, performance and reliability.

 

O.   What are the updates to the latest edition in pointwise of UL 9540A published on March 12, 2025?

The latest edition of UL 9540A covers key improvements that serve to streamline testing and drive towards consistency among test labs when conducting this test program.  Primary changes consist of the following:

    I.        Adding definition for thermal runaway propagation and clarify the criteria for establishing cell to cell propagation.

  II.        Specifying thermocouple locations  and adding option for a continuous thermal ramp for the Cell Level Test.

III.        Updating Module Level Performance Criteria to include a temperature limit for the module casing.

 IV.        Replacing the NFPA 286 fire test room with an instrumented wall for the Unit Level Test for residential BESS.

   V.        Requiring the inclusion of test summaries from previous level tests in Module, Unit, and Installation Level Test reports.

 VI.        Introducing test methods for high-temperature, lead acid, and nickel cadmium batteries, and refine the test method for flow batteries.

VII.        Enhancing unit level testing protocols for Rooftop and Open Garage installations.

VIII.        Permitting the Use of Gardon heat flux gauges for the Unit and Installation Level Tests.

 IX.        Implementing the use of flame ionization detection to measure total hydrocarbons as well as hydrogen measurements for the Unit and Installation Level Tests.

About Author:

Dr. Arindam Bhadra is a Fire safety consultant  & ISO Auditor based in Kolkata, India, with over 20 years of experience in Fire safety systems. He’s currently founding director of the Sprinkler Fire Safety Awareness and Welfare Foundation & SSA Integrate. He working on Fire Safety awareness, training, consultancy & Audit in same field. Dr. Arindam Bhadra is popularly known as "Fire ka Doctor" because of his expertise in fire safety, prevention, and awareness, helping people and organizations stay safe from fire hazards. He is Member of NFPA, Conformity Assessment Society (CAS), FSAI, Institution of Safety Engineers (India) etc. He is certified fire Inspector and certified Fire Protection professional.