CO2 extinguishers are the extinguisher of choice for electrical fires. Although they also work on flammable liquid (class B) fires

• Fires involving equipment such as computers, or generators (‘electrical’ fires)
• Fires involving some flammable liquids, such as petrol, diesel, and paint (‘class B’ fires)

• Cooking fires involving oil and grease, such as chip pan fires (‘class F’ fires)

CO2 fire extinguishers discharge CO2 gas, also known as carbon dioxide. This is stored in the extinguisher as a liquid, and the gas is created under pressure when the handle of the extinguisher is squeezed.
This causes the CO2 gas to emerge at great speed, which is why CO2 fire extinguishers are not recommended for chip pan fires – they could literally blast the flames into surrounding areas.
Unlike water and foam extinguishers, CO2 fire extinguishers do not work by cooling the fire and so are ineffective on fires involving flammable solids.
Instead, CO2 extinguisher work by replacing the oxygen surrounding the flames with carbon dioxide, meaning the fire can no longer burn.

Pros:extremely effective on electrical fires; do not leave any residue behind when they are used.
Cons: risk of cold burns if the user holds the extinguisher by the horn; less environmentally friendly than other types of extinguisher; they replace the oxygen in the air with CO2 so risk of asphyxiation if used in confined spaces. See the following link for a full article explaining the correct use of fire extinguishers in confined spaces.

CO2 fire extinguishers should be standard issue for premises with live electrical fire risk, such as:
• Offices
• Shops
• Schools
• Hospitals
CO2 fire extinguishers are particularly suitable for offices where there is a lot of electrical office equipment. Pairs of CO2 and Foam extinguishers are often recommended for this kind of internal environment, as this covers the vast majority of fire risks likely to be found.

Foam extinguishers are one of the most common types of fire extinguisher. They are generally used for fires involving flammable solids and liquids. They are general use and suitable for the majority of business premises.

Foam fire extinguisher uses:
• Fires involving flammable solids, such as paper, wood, and textiles (‘class A’ fires)
• Fires involving some flammable liquids, such as petrol, diesel, and paint (‘class B’ fires)
• Fires involving electrical appliances IF the extinguisher has passed the 35kv conductivity test

The 35kv conductivity test is an additional safety measure intended to safeguard users who accidentally use a foam fire extinguisher on an electrical fire – there is a risk to using a foam fire extinguisher this way, including the possibility of getting an electric shock.
We strongly recommend ONLY using a CO2 extinguisher or a Dry Powder extinguisher for electrical fire risk.
Read more about the different types of fire extinguisher. Learn what the different extinguisher colours signify

• Cooking fires involving oil and grease, such as chip pan fires (‘class F’ fires)
• Fires involving flammable gases, like methane and butane (‘class C’ fires)

Foam fire extinguishers work in 2 ways.
Firstly, they are mainly water-based and so have the same cooling effect as water extinguishers, putting the fire out by lowering the temperature.
Secondly, they contain ‘Aqueous Film Forming Foam’ (this is why they are also known as AFFF foam extinguishers).
AFFF works by smothering the fire and sealing in the flammable vapours. This prevents the fire re-igniting. It also allows foam fire extinguishers to put out flammable liquid fires, by creating a barrier between the liquid’s surface and the flames.

Pros:: non-toxic, non-damaging to most materials, largely safe if accidentally used on electrical fires (although this is not recommended), designed to prevent the re-ignition fires, lighter in weight than the equivalent water extinguisher.
Cons: : damaging to electrical appliances. Dangerous if used on cooking fires or flammable gas fires.

Foam fire extinguishers are the ideal extinguishers for premises with multiple fire risks, such as:
• Offices
• Warehouses
• Factories
• Garages
• Hospitals
In fact, most premises benefit from having foam extinguishers and these are frequently recommended, especially when paired with CO2 extinguishers for use on electrical fires.

Foam fire extinguishers need to be used differently, depending on the type of fire.
In all cases, firstly remove the safety pin – this will break the anti-tamper seal – and stand well back from the fire.