Blue band fire extinguisher: dry powder, and the catch indoors
A blue band marks a dry powder extinguisher. It tackles a wide range of fires and is safe on live electrics, which is why it is common outdoors and on vehicles. But the cloud it throws can blind and choke you indoors.
Contains: dry powder: multi-purpose (ABC) or standard (BC)
Fire classes: check the label: multi-purpose units cover solids, liquids and gases
Not for: chip and fat pan fires; metal fires, which need specialist powder
Caution: indoors, and for smouldering fires that can re-ignite
What a blue band means
Blue is the code for dry powder on the red extinguisher body. Powder units are the versatile all-rounders: fast knock-down, a wide range of fuels, and safe near live electrical equipment. That versatility is why they turn up on vehicles, in garages and plant areas, and outdoors.
How dry powder works
The powder smothers the flames and interrupts the chemical reaction that keeps the fire burning. It is quick, but it does not cool the fuel. Fire services warn that fires put out with powder can re-ignite, and smouldering deep-seated fires in upholstery or bedding are the usual culprits.
ABC powder or BC powder?
There are two common types, and the label tells you which you have.
- Multi-purpose (ABC) powder is rated for solids, flammable liquids and gases.
- Standard (BC) powder is rated for flammable liquids and gases, but not for ordinary solid combustibles.
Never mix different powders. It is one reason refilling and servicing belong to a competent person, not a keen amateur.
The indoor problem
Hereford & Worcester Fire and Rescue says powder is generally not for indoor use unless a risk assessment mitigates the problem. The discharge can suddenly reduce visibility and impair breathing. In a fire, you need to see the exit and breathe, so a unit that takes away both is a poor fit for a corridor in an occupied building. If your assessment does put one indoors, make sure staff know the risk and leave straight afterwards.
Never use it on
- Chip and fat pan fires. Use wet chemical in a commercial kitchen: see our yellow band guide.
- Metal fires (Class D). These need specialist powder extinguishers, which are not the same thing as the blue ABC unit on the wall.
Only fight a fire if it is small, you are trained, the alarm is raised and you have a clear exit behind you. Otherwise get out, stay out and call 999.
How to use it
- Outdoors, stand upwind. Indoors, keep your exit behind you.
- Aim at the base of the flames and sweep from side to side.
- Back away when it is out and keep watching for re-ignition.
- Leave the area and ventilate it before anyone returns.
Where it makes sense
Powder suits outdoor risks, vehicles, garages and some plant or workshop areas, where the benefits outweigh the visibility problem. In most offices and care homes, water, foam or CO2 is a better indoor default. This is a decision for your fire risk assessment, worked out to BS 5306-8.
Frequently asked questions
Is a dry powder extinguisher safe on electrical fires?
Fire services say it is safe on live electrical equipment, but the fire may re-ignite. Isolate the power if you can do so safely.
Why are powder extinguishers discouraged indoors?
The discharge can suddenly reduce visibility and impair breathing, which is a real problem when you need to find the exit.
What is the difference between ABC and BC powder?
ABC powder is rated for solids as well as liquids and gases. BC powder covers liquids and gases only. Check the label.
Related guides
- Fire extinguisher colours and chart: what each band means
- Which fire extinguisher for which fire?
- Yellow band fire extinguisher: wet chemical for cooking oil fires
- Cream band fire extinguisher: foam and where it fits
- Red band fire extinguisher: what water is for, and what it isn't
- Black band fire extinguisher: CO2 for electrical and liquid fires
Train the choice, not just the colour
Extinguisher Match includes the awkward cases, such as a fire where powder looks right but isn't.
Play Hazard Hunt →Sources
- Fire extinguishers (Hereford & Worcester Fire and Rescue Service)
- Fire extinguishers (Avon Fire & Rescue Service)
- BS 5306-10:2019, colour coding of portable fire extinguishers (BSI)
This guide is for learning and applies to England & Wales. Always work from the current standards, the label on your own extinguisher and your fire risk assessment; Scotland and Northern Ireland have equivalent regimes.