Which Fire Extinguisher Colours Mean What

Imagine... a small electrical fault sparks behind a server rack in a back office. Someone grabs the nearest Fire Extinguisher. Pulls the pin. Squeezes the handle. A jet of water hits live equipment... That's not a Fire Extinguisher problem. That's a colour-band problem, and it's exactly why the small strip of colour near the top of every extinguisher matters more than most people realise.

Portable Fire Extinguishers made to the current BS EN 3 series have predominantly red bodies. The UK's dedicated code of practice for colour-coding them, BS 5306-10:2019, sets out how the extinguishing medium is identified, and BS 5306-8:2023 covers how many you need and where they go. None of it is decoration. For any Responsible Person managing commercial premises in Kent or London, knowing what Fire Extinguisher colours mean is a practical part of keeping people safe.

Why Today's Fire Extinguishers Are Red

Under the current standards, the body is predominantly Signal Red (RAL 3000). A smaller colour-coded area, set out in BS 5306-10:2019, identifies the extinguishing medium inside, and that's the part worth learning to recognise. Water carries no separate band at all, so an entirely red extinguisher with nothing else on it is a water type. Foam is cream. CO2 is black. Dry powder is blue, except specialist Class D powder, which is violet. Wet chemical is yellow. A newer type, water mist, is commonly shown with white markings, usually a white panel rather than a full colour band, though it's worth checking the specific model's markings rather than relying on colour alone.

You won't find an all-blue or an all-black extinguisher manufactured to today's standard. If you've seen Fire Safety content written for the American market, it's worth resetting your expectations here. Older UK extinguishers before this standard were fully colour-coded body and all, and some of that content still circulates online. The British Standards are our floor, not our ceiling, and this is one area where getting the detail right genuinely changes how quickly someone reaches for the correct extinguisher under pressure.

UK Fire Classes: A, B, C, D and F

The UK follows the European classification system in BS EN 2, and there are five fire classes that matter for most commercial premises:

Class A covers solid combustible materials: wood, paper, cardboard, textiles and plastics. It's the most common class in offices, retail units, warehouses and schools.
Class B covers flammable liquids such as petrol, diesel, paint and solvents.
Class C covers flammable gases like propane, butane and methane. Portable extinguishers rarely tackle these directly; isolating the gas supply, if it's safe to do so, is the standard first response.
Class D covers combustible metals: lithium metal, magnesium, sodium and aluminium swarf. This is a specialist risk needing a specialist agent, not a standard extinguisher. Lithium-ion batteries are a different hazard again; despite the name, they are not a Class D fire, and a Class D extinguisher isn't the right tool for one.
Class F covers cooking oils and fats, the kind of fire you'd get from a deep fat fryer or a commercial kitchen appliance. It behaves very differently to a Class B liquid fire and needs a different response.

There's no Class E in the UK, and no Class K either, whatever you may have read elsewhere. Electrical faults don't get their own class here. What's actually burning, whether that's wood, liquid or oil, decides the class; the electrical fault is the cause, not the category. Whether a particular extinguisher is suitable for use near live electrical equipment, and under what conditions, is shown separately on the label, typically with an electric spark symbol; always check the specific model's markings and instructions rather than assuming from the extinguisher type alone.

Which Fire Extinguisher Colours Do What

Water (all red, no band) - Class A only. The most widely used type in general premises, but a standard water jet must never go anywhere near Class B liquids, Class F cooking fires or live electrical equipment; it conducts electricity, and that's a genuine electrocution risk, not a technicality. Some water-based extinguishers, most commonly water mist models, have passed the BS EN 3-7 dielectric test, run at 35kV, and are marked for use on live electrical equipment up to 1,000 V at a distance of 1 metre. That rating only applies to the specific model carrying it, shown by the electrical symbol on the label, and should never be assumed from the extinguisher type alone.

Foam (cream label) - Class A and Class B. A sensible choice where you've got both solid materials and flammable liquids on site. Don't assume a standard foam extinguisher is safe around live electrical equipment; check the specific model's markings, the same rule as for water.

CO2 (black label) - Class B rated, and commonly chosen for electrical risks. The standard choice for server rooms, comms cabinets and offices with significant IT kit, because it displaces oxygen and leaves no residue behind. What it won't do is cool the material down, so it's a poor choice for a Class A fire on its own; wood or paper can reignite once the gas disperses. Black, not blue. Confusing a CO2 extinguisher with a powder one is a genuinely dangerous mix-up, since neither agent behaves like the other once discharged.

Dry powder / ABC (blue label) - Class A, B and C rated, and many models suitable for use around live electrical equipment. On paper this looks like the universal answer. In practice, BS 5306-8:2023 recommends against specifying powder indoors unless a risk assessment genuinely justifies it. Discharge creates a cloud that badly impairs visibility, makes a serious mess and carries an inhalation risk. It tends to suit outdoor or vehicle use better than an occupied office or warehouse floor. Whether a specific model is rated for use near live electrics, and under what conditions, is on that model's own markings and instructions, not something you should assume from the extinguisher type alone.

Wet chemical (yellow label) - Class F and Class A. The right call for commercial kitchens and anywhere with deep fat fryers. It works by reacting with the burning oil to form a cooling, sealing layer, a process called saponification, and it also carries a Class A rating for solid materials nearby. It's not suitable for Class B liquids, Class C gases or Class D metals, and any suitability around live electrics again comes down to the specific model's markings, not the extinguisher type.

Specialist powder - Class D metal fires. Standard ABC powder is ineffective, and potentially dangerous, on metal fires. Under BS 5306-10:2019, new Class D powder extinguishers are marked violet rather than the blue used for ABC powder, precisely so the two don't get confused. If your site involves lithium metal, metal machining or reactive metals, this needs a specialist assessment rather than standard extinguisher provision. Lithium-ion batteries, the kind in laptops, power tools and e-bikes, are a separate question entirely: they're not a Class D risk. A portable extinguisher may not fully extinguish a lithium-ion fire, since the battery can keep generating heat or reignite, but the right agent can still help control it and cool nearby cells. What's right depends on the battery chemistry, the equipment and the scale of what you're storing or charging, so get that one specifically assessed rather than guessed at.

How Many Do You Actually Need, and Where

The Regulatory Reform (Fire Safety) Order 2005 puts the legal duty on you as the Responsible Person to carry out a suitable Fire Risk Assessment under Article 9, and to equip your premises with appropriate firefighting equipment under Article 13. The Order itself doesn't specify numbers or types. That detail sits in BS 5306-8:2023, and your Fire Risk Assessment is what translates that guidance into your specific building.

As a broad steer, BS 5306-8:2023 works on a minimum of one Class A rated extinguisher (at least 26A) for premises up to around 50 square metres, rising to at least two extinguishers with a combined minimum 26A rating for spaces up to 400 square metres, with more required again as the floor area grows. Extinguishers for specific risks, like electrical equipment or flammable liquids, need to be close enough to actually reach for, without the fire itself standing between you and the extinguisher. As a general guide, nobody should ideally have to travel more than 30 metres to reach a Class A extinguisher. Your Fire Risk Assessment, not this article, has the final word on the exact numbers and distances for your building.

Positioning matters as much as provision. Extinguishers up to 4kg are wall-mounted with the handle at roughly 1.5 metres from the floor; heavier units sit lower, at around 1 metre, so they can be lifted safely under pressure. They belong on escape routes and near identified hazards, securely wall-mounted or set on a proper stand, never left loose on the floor where they can be knocked over or missed entirely. In a kitchen, the wet chemical unit needs to be close enough to reach in seconds, but not so close that a fire at the fryer blocks the way to it.

Keeping Them Ready to Work

Provision on paper means nothing if the extinguisher hasn't been looked after. Article 17 of the Regulatory Reform (Fire Safety) Order 2005 places a legal duty on you to maintain firefighting equipment in efficient working order, and BS 5306-3:2017 provides the recognised code of practice for doing that.

There are four parts to it. Monthly visual checks, carried out by you or a nominated person on site, confirming the extinguisher is in place and undamaged, the tamper seal is intact and, where a pressure gauge is fitted, its needle sits in the green (CO2 units don't have one; those are checked by weight instead). An annual basic service by a competent engineer, within around a month either side of the anniversary. Extended servicing at five-year intervals for water, foam, powder and wet chemical units. And a ten-year overhaul for CO2 cylinders, involving a hydraulic pressure test. Your maintenance contractor will tell you when a particular unit has reached the end of its useful working life and needs replacing rather than servicing again.

Article 17 tells you the equipment must be kept in efficient working order; it doesn't itself spell out who has to carry that work out. In practice, that means using someone with the right competence, equipment and knowledge, following BS 5306-3:2017 and the manufacturer's instructions. BAFE recommends using a BAFE SP101 registered organisation for extinguisher sourcing, commissioning, siting, service and maintenance, and checking that the individual technicians attending site hold valid BAFE registration too, since technicians can only hold that status through a registered employer. Both are worth checking on the BAFE register itself rather than on trust.

Why Kent and London Businesses Choose Syndicate Fire Protection Service

We're Constructionline Approved, and third-party certificated by SSAIB under the BAFE SP203-1 scheme, which covers our fire alarm and detection maintenance work specifically, not extinguisher servicing under SP101. Our engineers train to EAL Level 3 across our fire safety disciplines, most recently at the ZZeus Centre of Excellence, where everyone on the course passed with over 90%. We don't sit still on that.

Every device we look after, including your Fire Extinguishers, sits on your Intelligent Asset List, tracked by QR code so you've got an instant, auditable record of what was checked, when and what was found. Wherever practical, it's the same multi-skilled engineer visiting your site each time, someone who knows your building rather than someone reading it off a clipboard for the first time. On your doorstep, not on a call centre queue.

Clients who bring their whole Fire Safety programme to us notice the difference in how visits are actually run.

"Projects have been managed professionally, with clear communication, good planning and a proactive approach."
Darius Zomorodian, Director, Jackson's Art Supplies, Ramsgate

If you're not sure your current Fire Extinguisher provision matches what your Fire Risk Assessment actually calls for, or it's simply been a while since anyone checked, our engineers can walk your site with you and set it straight. Book a free, no-obligation Fire Extinguisher survey, or if it's part of a wider check-up, ask about a combined Fire Systems Maintenance visit covering your alarms, Emergency Lighting and Fire Doors in the same appointment.

Call us on 01843 265 389, email info@syndicatefireprotection.co.uk, or get in touch online and we'll take it from there.