National Fire Protection Association (NFPA)

Rule Changes

Does not recognize ISO Class L in US-adopted codes

Lithium-ion battery fires now have their own fire class, after ISO published the third edition of ISO 3941 in January 2026 adding Class L for cells and batteries that contain no metallic lithium. New York City had already set a lower regulatory bar: its amended NFPA 855 requires FDNY approval for lithium-ion storage above 1 kilowatt-hour, against 70 kilowatt-hours for lead-acid.

Updated Oct 21