Fire class · UK/EU and US
Class C: gases in the UK, live electrical equipment in the US
First: raise the alarm, get out, call the fire service
UK: However, if in doubt, employees should not put themselves or anyone else at risk, but simply raise the alarm, leave the premises, and call the fire and rescue service.
HM Government (GOV.UK), A guide to making your small non-domestic premises safe from fire (accessible version), section ‘Fire extinguishers’
US: If you're unsure about whether it is safe to use a fire extinguisher, and for all other situations, alert others, leave the building, and call 911 from a mobile or neighbor's phone.
US Fire Administration (FEMA), Choosing and Using Fire Extinguishers, ‘Help people decide when to use a fire extinguisher’
UK: gases. US: live electrical equipment.
UK and Europe (BS EN 2 classes)
Fires involving gases.
HM Government (GOV.UK), Fire safety risk assessment: offices and shops (accessible version), Part 2, 3.1, Table 1: Class of fireClass C caused by flammable gases including methane, butane or hydrogen among others
Surrey County Council (Surrey Fire and Rescue Service), Extinguishers and fire blankets, ‘Fire Classes’
United States (NFPA 10 classes)
Fires that involve energized electrical equipment.
National Fire Protection Association (NFPA), Fire Extinguisher Ratings (NFPA Today blog, Brian O’Connor), table of classesFires in wiring, fuse boxes, energized electrical equipment, computers, and other electrical sources require an extinguisher labeled C.
US Occupational Safety and Health Administration (OSHA), eTool: Evacuation Plans and Procedures, Portable Fire Extinguishers, Extinguisher Basics, Fire classes
Extinguishers the guidance names for Class C
Extinguishers the guidance says not to use on it
- Water:
It should not be used for kitchen fires, fires caused by flammable gas and liquids as well as fires that involve electrical equipment.
Surrey County Council (Surrey Fire and Rescue Service), Extinguishers and fire blankets, ‘Water Extinguishers’ - Water:
Never use water to extinguish an electrical fire.
US Occupational Safety and Health Administration (OSHA), eTool: Evacuation Plans and Procedures, Portable Fire Extinguishers, Extinguisher Basics, Water (APW) extinguishers - Wet chemical:
Also keep in mind that if a Class K fire extinguisher is installed, there still needs to be extinguisher(s) available for any other combustible materials in the area since oftentimes a Class K extinguisher can’t be used on an ordinary combustibles fire, flammable liquids fire, electrical fire, or combustible metals fire.
National Fire Protection Association (NFPA), What Is a Class K Fire Extinguisher? (NFPA Today blog, Brian O’Connor), ‘Where should I install Class K fire extinguishers?’
Reading the letter
- The same letter means two different fires. On a UK or European label, C is a gas fire. On a US label, C means the extinguisher has passed a test for use on energised electrical equipment. Read which system the label follows before reading the letter.
You won’t see an extinguisher with only a C rating, they will always have an A and/or B rating as well. (When electrical equipment is de-energized, extinguishers rated for Class A or B fires are used.)
National Fire Protection Association (NFPA), Fire Extinguisher Ratings (NFPA Today blog, Brian O’Connor), ‘Class C fires’Class C fire extinguishers use an agent that doesn't conduct electricity.
US Fire Administration (FEMA), Choosing and Using Fire Extinguishers, the five types
Other fire classes
Sources
Official guidance only: UK government, UK fire and rescue services, the Fire Industry Association, NFPA, OSHA and the US Fire Administration. Words in quotation marks are theirs.
- HM Government (GOV.UK): Fire safety risk assessment: offices and shops (accessible version) (updated 12 September 2023). Quoted here: Part 2, 3.1, Table 1: Class of fire. www.gov.uk Checked 2026-09-29.
- Surrey County Council (Surrey Fire and Rescue Service): Extinguishers and fire blankets (reviewed 24 August 2026). Quoted here: ‘Fire Classes’; ‘Water Extinguishers’. www.surreycc.gov.uk Checked 2026-09-29.
- National Fire Protection Association (NFPA): Fire Extinguisher Ratings (NFPA Today blog, Brian O’Connor) (26 August 2022). Quoted here: table of classes; ‘Class C fires’. www.nfpa.org Checked 2026-09-29.
- US Occupational Safety and Health Administration (OSHA): eTool: Evacuation Plans and Procedures, Portable Fire Extinguishers, Extinguisher Basics (no date shown). Quoted here: Fire classes; Water (APW) extinguishers. www.osha.gov Checked 2026-09-29.
- HM Government (GOV.UK): A guide to making your small non-domestic premises safe from fire (accessible version) (updated 20 January 2025). Quoted here: section ‘Fire extinguishers’. www.gov.uk Checked 2026-09-29.
- US Fire Administration (FEMA): Choosing and Using Fire Extinguishers (page last reviewed 1 April 2023). Quoted here: ‘Help people decide when to use a fire extinguisher’; the five types. www.usfa.fema.gov Checked 2026-09-29.
- National Fire Protection Association (NFPA): What Is a Class K Fire Extinguisher? (NFPA Today blog, Brian O’Connor) (12 August 2024). Quoted here: ‘Where should I install Class K fire extinguishers?’. www.nfpa.org Checked 2026-09-29.