Electrical fires can develop quickly and create a serious risk of electric shock, toxic smoke and damage to valuable equipment. Using the wrong extinguisher may spread the fire or expose the user to electrocution.
For fires involving live electrical equipment, the most commonly recommended option is a carbon dioxide extinguisher, usually called a CO₂ fire extinguisher. UK Health and Safety Executive guidance identifies CO₂ extinguishers as appropriate for electrical fire risks.
Which Fire Extinguisher Should You Use for an Electrical Fire?
A CO₂ fire extinguisher is generally the preferred extinguisher for fires involving live electrical equipment.
It is commonly installed near:
- Computers and office equipment
- Electrical switchboards
- Server and communication rooms
- Machinery and control panels
- Photocopiers and printers
- Commercial kitchen appliances
- Electrical plant rooms
Government fire-safety guidance also recommends providing a carbon dioxide extinguisher where fires involving electrical equipment may occur.
How Can You Identify a CO₂ Fire Extinguisher?
In the UK, a CO₂ extinguisher normally has:
- A red cylinder
- A black identification panel
- The words “Carbon Dioxide” or “CO₂”
- A discharge horn instead of a standard hose
- No pressure gauge on many common models
Always read the extinguisher label before attempting to use it. Never assume that an extinguisher is suitable based only on its location or appearance.
Why Is CO₂ Suitable for Electrical Fires?
CO₂ extinguishers discharge carbon dioxide gas around the burning equipment. This reduces the oxygen available to support the flames and helps suppress the fire.
It Does Not Conduct Electricity
CO₂ is non-conductive, making it suitable for use around electrical equipment that may still be live.
It Leaves No Residue
Unlike dry powder, CO₂ does not leave a layer of extinguishing agent behind. This makes it particularly useful around computers, servers and sensitive electronic systems.
It Can Control Small Fires Quickly
When used correctly during the early stages of a fire, a CO₂ extinguisher can suppress flames before they spread to surrounding materials.
However, CO₂ has a limited cooling effect. If the equipment remains hot or electrically energised, the fire may reignite.
Can a Dry Powder Extinguisher Be Used?
A dry powder extinguisher can be used on certain fires involving electrical equipment. Some UK fire-service guidance states that dry powder extinguishers may be used around electrical equipment within their stated voltage rating.
However, dry powder is not always the best option for indoor environments because it:
- Leaves significant residue
- Can damage sensitive equipment
- May reduce visibility
- Can irritate the respiratory system
- Makes cleaning difficult
- Can interfere with evacuation
Fire and rescue services warn that dry powder should generally not be used in enclosed spaces because the powder can affect breathing and reduce visibility.
For offices, server rooms and similar indoor locations, CO₂ is usually the more practical choice.
Which Extinguishers Should Not Be Used?
Selecting the wrong extinguisher can make an electrical fire more dangerous.
Water Extinguishers
A standard water extinguisher must not be used on live electrical equipment. Water conducts electricity and can create a serious risk of electric shock.
Some specialist water-mist extinguishers are tested for use around particular electrical risks, but they should only be selected according to their rating and professional fire-risk advice. Do not treat an ordinary water extinguisher as suitable for an electrical fire.
Foam Extinguishers
Foam extinguishers are primarily intended for Class A combustible materials and Class B flammable liquids. They are not generally recommended for live electrical equipment.
Wet Chemical Extinguishers
Wet chemical extinguishers are designed mainly for fires involving cooking oils and fats. They are normally found in commercial kitchens and should not be treated as the standard solution for live electrical equipment.
Are Electrical Fires Class C Fires?
This is a common source of confusion.
Under the UK fire classification system, Class C refers to fires involving flammable gases, not electrical equipment.
Some information published in other countries describes electrical fires as Class C fires. In the UK, electrical equipment is normally treated as an additional electrical hazard rather than as its own standard fire class.
The underlying material may become a Class A or Class B fire after the electricity has been safely isolated. This is why extinguisher selection should be based on a professional fire-risk assessment.
Common Causes of Electrical Fires
Electrical fires may be caused by:
- Overloaded extension leads
- Damaged cables or plugs
- Loose electrical connections
- Faulty appliances
- Overheating equipment
- Poorly maintained wiring
- Incorrectly installed electrical systems
- Blocked ventilation around equipment
- Counterfeit or unsuitable chargers
- Defective batteries
Regular electrical inspections, appliance testing and proper maintenance can reduce the likelihood of these incidents.
What Should You Do If an Electrical Fire Starts?
Your personal safety must always come first.
1. Raise the Alarm
Activate the fire alarm immediately and alert everyone in the building.
2. Call the Emergency Services
Call 999 and provide clear information about the location and nature of the fire.
3. Isolate the Electricity Only If It Is Safe
Switch off the appliance or electrical supply only when this can be done without approaching the fire or exposing yourself to danger.
Do not touch burning equipment, damaged cables or exposed electrical components.
4. Begin Evacuation
Follow the building’s emergency procedure and use the nearest safe escape route. Do not delay evacuation to collect personal belongings or attempt to save equipment.
5. Only Use an Extinguisher When It Is Safe
Only attempt to extinguish a fire when:
- The fire is small and contained
- The alarm has already been raised
- You have received appropriate training
- You have the correct extinguisher
- Smoke is not affecting your escape route
- You can keep a safe exit behind you
- The extinguisher is safe to approach
If the fire is growing, producing heavy smoke or blocking the exit, leave immediately and close doors behind you where possible.
How Do You Use a CO₂ Extinguisher?
Always follow the instructions printed on the extinguisher. The general process is:
- Remove the safety pin or tamper seal.
- Stand at a safe distance from the fire.
- Point the discharge horn towards the base of the flames.
- Squeeze the operating handle.
- Move the discharge from side to side.
- Watch carefully for signs of reignition.
Never hold the discharge horn on a standard CO₂ extinguisher while it is operating. The horn can become extremely cold and may cause a cold burn or freeze injury.
CO₂ can also displace breathable air, so additional caution is required in confined or poorly ventilated spaces.