How to Read Battery Storage Safety Certificates: UL 9540 vs UL 9540A, IEC 62619 vs IEC 63056, NFPA 855 and China's GB Rules

Short answer. Storage safety documents sit at three levels. Product standards (UL 9540, UL 1973, IEC 62619, IEC 63056, GB 44240, GB/T 36276) say a cell, battery or system passed defined tests. Fire-propagation test methods (UL 9540A) produce a report describing what happened when a cell was forced into thermal runaway — a report, not a pass/fail certificate. Installation and project rules (NFPA 855 in North America; China's GB/T 42288 and the NEA's 2022 safety notice) say what the site must do with those results. A seller who hands over "the UL 9540A" has given you one piece of one level. This guide explains the pieces from the standards bodies' own pages and the Chinese rule texts. It rates no product.

Level 1: product standards

UL 9540 — the system listing

UL 9540 (Energy Storage Systems and Equipment) covers an ESS intended to receive and store energy and supply electrical energy to loads or the local/area electric power system; electrochemical, chemical, mechanical and thermal ESS are covered, built either as one unitary piece of equipment or as matched assemblies that form the ESS when connected per the manufacturer's installation instructions. Edition 3 was published 28 June 2023; its latest revision, dated 7 March 2025, is ANSI- and SCC-approved and adds Annex H on manufacturer installation instructions for residential ESS. Systems are intended for installation under NFPA 70, CSA C22.1, IEEE C2, the ICC IFC and IRC, the NRC NFC, NFPA 1 and NFPA 855; the standard covers stationary indoor and outdoor, residential and non-residential installations, and mobile ESS as defined.

The clause buyers most often miss is the energy cap. UL 9540 limits an individual electrochemical ESS to 20 kWh (residential) and 50 kWh (non-residential) unless UL 9540A results allow more: the residential cap may rise to the unit size that meets the UL 9540A unit-level criteria; the non-residential cap may rise to the size meeting the installation-level criteria (with marking); there is no cap for non-residential ESS where the cell-level criteria are met, nor for non-residential ESS in remote outdoor locations (marked accordingly). NFPA 855 defines a remote outdoor location as more than 30.5 m (100 ft) from exposures. In other words, capacity above the cap rests on one of several routes: a UL 9540A unit-level, installation-level or cell-level result, or, for non-residential ESS, the remote-outdoor exception with its marking, which the scope text does not tie to a UL 9540A result. The size of a unit does not show which route was used, or that any UL 9540A level was tested; check the listing and the unit's marking for the route that applies to the capacity being bought.

UL 9540 draws on component standards and codes including UL 1973 (batteries for stationary, vehicle auxiliary power and light electric rail applications), UL 1741 (inverters, converters, controllers and interconnection equipment for DER), IEEE 1547/1547.1, CSA FC1, NFPA 70 and NFPA 2. UL Solutions also lists UL 9540B as an Outline of Investigation for a large-scale fire test for residential battery ESS, distinct from UL 9540A.

IEC 62619 and IEC 63056 — the cell and battery standards

IEC 62619:2017 specifies requirements and tests for the safe operation of secondary lithium cells and batteries in industrial applications, including stationary applications such as electrical energy storage systems; it covers requirements common and minimum to the various applications, and electrical safety is included only as part of the risk analysis, with end-use application standards to be considered for details. IEC 63056:2020 (edition 1.0, published 27 March 2020) specifies product-safety requirements and tests for secondary lithium cells and batteries used in electrical energy storage systems with a maximum DC voltage of 1 500 V (nominal); basic safety requirements are in IEC 62619 and IEC 63056 adds the additional or specific requirements for EES systems, including large on-grid/off-grid storage. A certificate citing IEC 62619 alone is therefore a general industrial-battery certificate; one citing IEC 63056 is specific to storage.

China's GB standards

GB 44240-2024 "Secondary lithium cells and batteries used in electrical energy storage systems—Safety requirements" is a mandatory national standard (GB, not GB/T) issued 24 July 2024, in force from 1 August 2025, administered by MIIT. GB/T 36276-2023 "Lithium ion battery for electrical energy storage" was issued 28 December 2023, implemented 1 July 2024, and is administered by the China Electricity Council. The first is the compulsory safety floor for batteries sold into storage in China; the second is the voluntary performance and test standard the power sector uses. A Chinese test report should name which of the two it was run against, and its edition.

Level 2: the fire-propagation test method

UL 9540A is the American and Canadian national standard for assessing fire propagation from thermal-runaway events in battery ESS; UL Solutions offers testing to both the 5th and 6th editions. It provides a methodology for testing safety-related behaviour when an ESS design or installation exceeds the limits set by NFPA 855, NFPA 1, the IFC or the IRC, and is the only consensus standard explicitly cited in NFPA 855 for large-scale fire testing.

The method is tiered. Cell-level testing evaluates the cell's thermal-runaway characteristics and the composition and flammability of its gases; module-level testing evaluates propagation tendency, heat and gas release rate and the danger of ignition or deflagration; unit-level testing evaluates fire spread between modules, the unit's heat and gas release rates and the potential for deflagration or re-ignition. PNNL describes the purpose plainly: in a UL 9540A test thermal runaway is intentionally created to observe how fire spreads through the unit, which informs fire-safety features and safe distances between units.

Editions move. According to UL Solutions, the 2026 edition of NFPA 855 adds Annex G.11 on large-scale fire testing for fire spread from one BESS to another, and UL 9540A Edition 6 updates the installation-level test with a more challenging fire scenario assuming a post-deflagration condition. A 9540A report should therefore state its edition and the level tested, and the tested configuration (cell, module, unit, spacing, suppression) should match what is being bought.

Level 3: installation codes and project rules

NFPA 855 in North America

PNNL (October 2023) explains that in the U.S. a code guides installation requirements while a standard describes product safety requirements and certification testing; UL 9540 is the key product safety standard for ESS and listing to it is required by both the IFC and NFPA 855. NFPA 855 was initially created to address the risks of lithium-ion chemistries and covers design, installation, commissioning, repair/replacement, explosion control and decommissioning; PNNL lists requirements with direct relevance to local officials — an emergency response plan and responder training (Section 4.3), use of UL 9540-listed equipment (4.6), fire control and suppression (4.9), a decommissioning plan (8.1), site/facility construction requirements (9.3–9.5) and explosion control (9.6). PNNL also notes that NFPA 855 can be read free of charge after registering on the NFPA website, and that the fundamental risk question for a well-designed project is what happens if a single unit fails rather than if every unit fails at once.

China's project rules

GB/T 42288-2022 "Safety code of electrochemical energy storage station" was issued 30 December 2022, took effect 1 July 2023, and is administered by the China Electricity Council. The NEA's 2022 notice on electrochemical storage safety (国能综通安全〔2022〕37号, 26 April 2022) makes the owner the responsible party for safe operation of stations connected to the public grid at 10 kV and above that are under filing management, and requires selected equipment and systems to meet national/industry standards and pass inspection by bodies with storage-specific testing qualifications.

The notice then sets a sequence that reads like a document checklist: arrival sampling inspection of batteries and their management systems by qualified bodies with batch-consistency sampling; completion acceptance including fire acceptance before commissioning; and type tests, whole-station commissioning tests and grid-connection testing before grid acceptance, with grid companies refusing stations that do not meet connection standards. In operation it requires battery state-of-health assessment, reporting of battery safety performance and operating-state information to a safety-monitoring platform, staff training on thermal runaway and fire characteristics, emergency drills for electrolyte leakage, thermal runaway and fire, and filing of emergency plans with local emergency-management and fire-rescue authorities.

What to ask for, by level

Scope limits

NFPA 855's own text was not read (the NFPA product page renders only via script); its edition and clause facts come from UL and PNNL descriptions. IEC and GB full texts were not read. No test report or certificate from any manufacturer is shown, and no product or laboratory is named or rated. Certificate validity must be checked with the issuing body.