Advising and Installing for over 25 years

    It’s a legal requirement that all commercial premises have a minimum of two class A fire extinguishers on every floor of the building unless it is a very small premises, in which case one may be acceptable. It’s also a legal requirement that they have at least two, 2kg CO2 extinguishers on every floor, and these have to be 5kg extinguishers if there is any 415-Volt rated equipment.

    As commercial buildings get bigger, their requirements get more complex, which is why Chris Lewis is here, to advise you on your legal requirements and help you determine which type of extinguishers you do and don’t require. 

    Fire Extinguishers

    Undertstanding Fire Classes

    When dealing with any type of fire the main priority, once everybody is safe, is to fully understand what type of fire you are dealing with so that you can act accordingly. As an example, if you were to throw water over an oil fire the results would be disastrous as this only makes things worse. Once you understand what type of fire you are dealing with you can choose the correct extinguisher for your requirements.

    IMPORTANT: You should only consider using a fire extinguisher if everybody has been alerted to the fire and the fire brigade has been called. You should also ensure you are safe from smoke and that the fire is not between you and your only escape route.


    Water extinguishers should only be used for Class A fires which involve organic materials such as wood, paper, coal, and cardboard. It’s a legal requirement of most commercial buildings to have a Class A extinguisher, but a foam extinguisher is often preferred due to its ability to also deal with Class B fires.

    You would consider using a water extinguisher over a foam extinguisher because it creates less mess and can also cover a larger surface area than most extinguishers, whilst using a mist of water to help protect you from the heat of the fire.

    Water Extinguishers

    Foam extinguishers are suitable for dealing with Class A and Class B fires which involve organic materials and flammable liquids. As it’s a legal requirement for all commercial buildings to have Class A fire extinguishers on every floor, the foam extinguisher is the most commonly found of all extinguishers because, unlike water extinguishers, they also deal with Class B fires.

    Foam Extinguishers

    Also known as an ABC extinguisher (because of the fire Classes they can be deployed on) these extinguishers come with the added benefit of being able to be used on Class D and Class E fires as well, meaning they are suitable for use on electronics and flammable metals. However, the primary reason they are not preferred in most environments is because they should not ideally be used in confined spaces and it’s not easy to clear up the leftover residue once the fire is over.

    This type of extinguisher is only suitable for electrical fires under 1000v (a plug socket is 120v as a benchmark) and in the case of some metals such as magnesium and titanium you will require specialist dry powder extinguishers.

    Dry Powder

    Designed for use on Class F fires (cooking oils and fats) this extinguisher can also be used on Class A fires, but water or foam extinguishers are more commonly used here. This type of extinguisher is a legal requirement in commercial kitchens and should be used inside this environment alongside a fire blanket. This is the only type of extinguisher you should use on Class F fires. 


    These are mainly used for Class E fires (electrical) as the CO2 suffocates the fire by displacing the oxygen it requires to continue burning. These are a legal requirement in all commercial environments where electronics are used, which is pretty much everywhere, and the size of the extinguisher required depends on the voltage of equipment you use. These extinguishers can also be used on Class B fires.

    These can often be found in server rooms as well but in most cases, we would suggest a full suppression system inside server rooms to protect valuable data which may be irreplaceable.

    Wet Chemical
    Andrew Pitts

    “Chris Lewis Fire and Security have high quality and very knowledgeable engineers. They have provided a great service to us for many years now and have never let us down. Their customer service team is extremely responsive and nothing is too much trouble.”

    Fire Extinguisher Commissioning & Servicing

    As part of the Regulatory Reform (Fire Safety) Order 2005 any equipment such as fire extinguishers ‘should be subject to a suitable system of maintenance and be maintained in an efficient state, in efficient working order, and in good repair’. Essentially this means that you need to have your fire extinguishers commissioned on-site by a competent person to the BS 5360-3 standard before you can certify that you have fulfilled your responsibility in accordance with your commercial fire risk assessment. This commissioning even applies to brand new extinguishers as they could have been damaged, discharged, or lost pressure during delivery.

    After the initial commissioning, in accordance with the BS 5036-6 regulation, you must visually inspect your extinguishers monthly, have them undergo a basic service every 12 months, and then have them undergo an advanced service every 5 years. Note: CO2 extinguishers are higher pressure and so require different servicing, with an extended service required every 10 years and is called an overhaul.

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