ISO Introduces Class L Fire Classification for Lithium-Ion Batteries
ISO's new Class L fire classification for lithium-ion batteries is crucial for UK fire safety professionals to understand due to the prevalent use of these batteries.
INFIRISK Team·2 min read·
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The International Organization for Standardization (ISO) has introduced a new fire classification, Class L, specifically for lithium-ion batteries. This development is significant for UK fire safety professionals, as lithium-ion batteries are widely used across various sectors, and understanding their fire risks is essential for compliance and safety.
Understanding Class L Classification
The third edition of ISO 3941, published on 21 January 2026, establishes Class L for fires involving lithium-ion cells and batteries that do not contain metallic lithium. This classification distinguishes these incidents from Class D fires, which involve combustible metals such as lithium-metal batteries. The standard identifies several defining characteristics of lithium-ion battery fires, including high energy density, rapid fire growth, and the risk of reignition.
Implications for UK Fire Safety
For UK fire safety professionals, the introduction of Class L is a call to reassess the risks associated with lithium-ion batteries. These batteries are prevalent in many industries, from consumer electronics to electric vehicles, and understanding their unique fire risks is crucial for effective fire safety management. The ISO classification provides a framework for identifying and mitigating these risks.
Lessons from New York City
New York City has already begun to address the hazards posed by lithium-ion batteries through its amended NFPA 855 framework, which applies to energy storage systems above 1 kWh. This approach highlights the importance of assessing even small installations for fire risk. The Fire Department of New York (FDNY) recorded 277 lithium-ion battery fires in 2024, underscoring the ongoing risk these batteries pose.
UK Regulatory Context
In the UK, the Regulatory Reform (Fire Safety) Order 2005 is the primary legislation governing fire safety. While the ISO classification does not directly alter UK regulations, it provides a framework that can be integrated into existing safety assessments. The focus is on ensuring that fire safety measures are adequate for the specific risks posed by lithium-ion batteries, which may require updates to fire risk assessments and safety protocols.
The new classification affects a wide range of sectors, including consumer electronics, automotive, and energy storage. Each of these sectors uses lithium-ion batteries extensively, and the risks associated with these batteries must be carefully managed. The ISO classification helps provide clarity and guidance on how to handle these risks effectively, ensuring that fire safety measures are both comprehensive and compliant with international standards.
Practical Takeaways for UK Professionals
Assess lithium-ion batteries as a distinct fire risk, separate from ordinary combustibles.
Consider the battery chemistry, capacity, and storage arrangements when planning fire safety measures.
Ensure that fire protection systems are suitable for the specific risks posed by lithium-ion batteries.
Stay informed about international standards and local regulations to ensure compliance and safety.
