As of 2026, lithium-ion batteries have their own fire class—here is everything you need to know to stay safe.
What is a Class L Fire?
A Class L fire is a fire that involves lithium-ion batteries. This is a new category added in January 2026 under the ISO 3941:2026 standard.
For a long time, these fires were called “Class A” (solids) or “Class B” (liquids). But battery fires are different. They don’t just burn on the outside. They have a chemical reaction happening on the inside.
The Difference Between Class D and Class L
You might know Class D for metal fires. It is important to know the difference:
- Class D: For fires involving lithium metal (like in a lab).
- Class L: For lithium-ion batteries (like in your phone or e-bike). These do not contain raw lithium metal, so Class D extinguishers do not work well on them.
Why Do We Need Class L Extinguishers?
Standard extinguishers (like ABC powder) often fail against batteries. A battery fire is like a tiny volcano. It creates its own heat and its own oxygen.
The Danger of Thermal Runaway
The biggest risk is thermal runaway. This is a chain reaction.
- One battery cell gets too hot.
- It pops and catches fire.
- The heat moves to the next cell.
- The whole battery pack explodes in a loop.
Class L extinguishers are built to stop this specific loop.
How Does a Class L Extinguisher Work?
A Class L extinguisher does two jobs at once. It cools and it seals.
Cooling vs. Smothering
- Cooling: It uses special agents like Aqueous Vermiculite Dispersion (AVD) or Hydrated Mica Suspension (HMS). These soak up the heat much faster than water.
- Smothering: The agent turns into a hard “crust” over the battery. This blocks the fire from spreading to other cells.
Key Standards and Regulations (ISO 3941:2026)
In 2026, the International Organization for Standardization (ISO) updated the rules.
- ISO 3941:2026 officially named Class L.
- It requires businesses to list “Class L risks” in their fire safety plans.
- New extinguishers must pass the prEN 3-11 test to show they can stop battery fires.
Where Should You Use Class L Extinguishers?
You should keep a Class L extinguisher anywhere you charge or store batteries. This includes:
- Home: Near e-bike and e-scooter charging spots.
- Office: In server rooms or near laptop charging stations.
- Industry: In warehouses that store power tools.
- Transport: At EV (Electric Vehicle) charging points.
How to Identify a Class L Extinguisher
Look for the letter “L” on the label.
- Most will have a blue or white circle with a battery icon.
- The label will state it is “Tested for Lithium-ion Battery Fires.”
- Warning: If it only says “ABC,” it is not a Class L extinguisher.
Summary: Staying Safe with New Battery Tech
Technology moves fast, and fire safety is finally catching up.
- Class L is the official name for battery fires.
- Standard extinguishers usually won’t stop a battery from re-igniting.
- Early action with a Class L unit can prevent a total building fire.
FAQs
1. Can I use water on a Class L fire?
You can use water, but you need a lot of it. Water cools the fire, but it does not always stop the chemical reaction inside the battery. A Class L extinguisher is much faster and uses less liquid.
2. Will my old ABC extinguisher work?
It might put out the flames on the outside (like the plastic casing), but it will not stop thermal runaway. The battery will likely catch fire again a few minutes later.
3. Why was Class L added in 2026?
Because more people use e-bikes, EVs, and large home batteries now. The old rules didn’t help firefighters deal with these specific “internal” chemical fires.4. Where can I buy a Class L extinguisher? Look for suppliers that mention ISO 3941:2026 compliance. They are becoming the standard in hardware and safety stores this year.
