Class L Label Confusion: Why Battery Storage Fire Rating Is Not a Standard

Buying traditional fire safety equipment operates on a strict physical guarantee: a Class A or Class B label means the product has passed a legally mandated suppression test against burning wood or flammable liquids. The new Class L designation for lithium-ion battery fires appears identical on a product label, but it differs in one critical respect: it defines the behavior of the fire, but it does not legally require the product to pass a test against one.[1]

That distinction has created a regulatory blind spot just as lithium-ion battery use surges across residential and commercial properties. In 2026, the International Organization for Standardization published ISO 3941:2026, introducing Class L to categorize fires driven by the internal electrochemical reactions of lithium-ion cells. It marks the first new fire classification in 30 years, following the creation of Class F for cooking oils in 1996.

However, the classification arrived without a harmonized testing standard. Manufacturers of battery storage cabinets and fire extinguishers are increasingly applying "Class L" marketing labels to products that have only been tested against traditional Class A fires. This leaves facility managers and homeowners assuming they are protected against thermal runaway events when the equipment has never actually faced one.[1][2]

Regulators are now stepping in to police the resulting market confusion. On August 31, 2026, the Australian Competition and Consumer Commission (ACCC) forced suppliers of lithium-ion fire extinguishers to amend their marketing claims. The watchdog found that companies were falsely implying compliance with Australian safety standards that do not currently exist for lithium-ion fires. The intervention follows a 600 percent increase in lithium-ion battery safety reports to the ACCC between 2020 and 2025.[2]

"The ACCC's view is that lithium-ion battery fire extinguishers should not be marketed as being suitable for use by members of the general public," stated ACCC Deputy Chair Catriona Lowe. She noted that the devices require professional training and protective gear. "Lithium-ion battery fires can spread rapidly, produce toxic smoke and can be very difficult to extinguish," Lowe added, advising consumers to evacuate rather than attempt suppression.[2]

The labeling issue extends beyond extinguishers to the cabinets used to store power tools, e-bikes, and IT equipment on construction sites and in office buildings. Writing in Building Design on September 1, 2026, Matt Partridge, head of product development at Armorgard, warned that the "Class L approved" label on a storage cabinet tells a buyer almost nothing about its performance in a real emergency.[1]

A Class L fire behaves fundamentally differently from a traditional combustion event. During thermal runaway, a failing cell's temperature can exceed 400 degrees Celsius within seconds, releasing toxic gases like hydrogen fluoride before any flame is visible. Because the fire generates its own oxygen internally, traditional smothering techniques fail, and stranded electrical energy can cause re-ignition hours or even days later.

According to Partridge, the ISO standard describes Class L as "particularly useful in the context of [testing] equipment," which functions as a recommendation rather than a legal mandate. "Nothing compels manufacturers to test their equipment against a lithium-ion fire before bringing it to market," he noted. A cabinet could pass every existing fire test without ever facing the specific heat and pressure hazards of thermal runaway.[1]

The confusion over safety standards and fire behavior is also affecting grid-scale energy deployments. In California, which has expanded its Battery Energy Storage System (BESS) capacity from 4,000 megawatts in 2022 to 21,000 megawatts in 2026, public anxiety over battery fires remains a primary hurdle for new utility projects, despite the fact that grid-scale facilities use highly engineered cell-level cooling architectures.[3]

"The biggest obstacle to energy storage by far in California at this point is local opposition and misunderstandings of the true safety implications of energy storage," said Scott Murtishaw, executive director of the California Energy Storage Alliance (CESA), on August 24, 2026. While the commercial industry has largely solved propagation control, the broader public confusion over battery fire safety continues to complicate local permitting.[3]

Until national testing standards are updated to mandate physical thermal runaway tests for Class L products, the burden of verification falls entirely on the buyer. Facility managers and homeowners purchasing storage for e-bikes or power tools must look past the marketing label and demand engineering data proving the enclosure can actually vent toxic gases and contain cell-to-cell propagation.[1][2]