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Using the wrong type of fire extinguisher: risks, consequences and what to do

Introduction

Using the wrong type of fire extinguisher can make a fire worse and put people at serious risk; in this guide you will learn why choosing the right extinguisher matters, the common mistakes to avoid, and the practical steps property managers and responsible persons should take to reduce harm.

Why the type of extinguisher matters

Fires behave differently depending on what fuels them. For example, a cooking oil fire reacts very differently from a paper or electrical fire. Therefore, each type of extinguisher uses a different extinguishing agent and method. If you fight a fire with the wrong agent, you may spread burning material, cause re-ignition, or create toxic gases.

Most workplace guidance requires you to provide appropriate portable firefighting equipment after a fire risk assessment. For small non-domestic premises, the government’s guide covers the basic pairing of extinguisher types to likely fire sources and why suitability is essential. You should consult that guidance when planning your fire safety provision. GOV.UK guidance on fire extinguishers for small premises.

Common mistakes that lead to wrong extinguisher use

The most frequent errors are simple but dangerous. First, staff use water on a fat or oil fire. Water can cause burning oil to splash and spread, rapidly enlarging the incident. Second, people aim water at live electrical equipment. Water conducts electricity and increases risk of electric shock and electrical spread. Third, bystanders select a multipurpose extinguisher without checking its ratings; not all multipurpose types cover deep-fat cooking or certain chemical fires.

In practice, lack of training and unclear signage cause most mistakes. Therefore, regular training and accurate signage reduce the chance of someone using an inappropriate extinguisher during an emergency. For practical training and refresher courses, consider booking structured sessions that include hands-on practice. Total Safe fire extinguisher training can help ensure staff know which extinguisher to use and when to evacuate instead.

What can happen physically when the wrong extinguisher is used

Using the wrong extinguisher can cause these immediate effects:

Re-ignition: some agents do not cool the burning material sufficiently, so the fire restarts.

Spread of burning material: applying the wrong stream can push burning liquids or embers into new areas.

Explosion risk: certain extinguishing agents react violently with particular chemicals or metals.

Toxic fumes: wrong formulations may generate hazardous gases when they contact certain materials.

Therefore, the potential consequences extend beyond a failed attempt to put the fire out. In confined spaces, toxic smoke or a chemical reaction can create life-threatening conditions in seconds. For guidance on workplace fire control and means of escape, see the HSE’s overview on general fire safety. HSE general fire safety guidance.

Which extinguisher types are commonly used and where they belong

Understanding basic extinguisher types helps avoid selecting the wrong one. Here is a concise summary:

Water: for Class A fires (wood, paper, textiles). Do not use on fats, oils or electrical equipment.

Foam: for Class A and flammable liquids (Class B). Useful in offices and stores with liquid hazards.

Carbon dioxide (CO2): for electrical fires and Class B liquid fires. Leaves no residue, so good for IT rooms.

Dry powder: versatile for A, B and C fires; used where multiple risks exist but it leaves a powdery residue and can harm sensitive equipment.

Wet chemical: specifically for deep-fat cooking and kitchen oil fires (Class F). It forms a cooling soap layer to prevent re-ignition.

Place extinguishers so they are accessible but not too close to the hazard; for example, you should not mount a kitchen’s wet chemical extinguisher right next to a fryer where a fire would block access.

Employers and responsible persons have duties under fire safety law to provide appropriate firefighting equipment where necessary. If your fire risk assessment identifies extinguishers as necessary, you must ensure they are suitable, maintained and accessible. Failure to meet those duties can lead to enforcement action, fines or prosecution under the Fire Safety Order.

Moreover, insurers expect you to keep equipment serviced and appropriate for the risk. Using or supplying the wrong type could void insurance cover after an incident. To reduce legal exposure, ensure your fire risk assessment lists suitable extinguisher types and locations. If you need support with assessments and remedial works, Total Safe provides comprehensive fire safety services and maintenance that align with statutory expectations. Explore Total Safe fire safety services.

Human factors: why people choose the wrong extinguisher under stress

In an emergency, people act under stress and time pressure. They often reach for the nearest red cylinder without checking the label. In addition, panic can override training, and poor signage causes hesitation or wrong choice. Therefore, practical measures help:

Place clear, durable signage above extinguisher locations.

Keep instructions visible on the extinguisher body and nearby signage.

Run realistic training and drills that include decision-making under time pressure.

Regular drills and visible signage create muscle memory. Consequently, staff are more likely to pick the correct extinguisher and use it safely when every second counts.

What to do if the wrong extinguisher has been used

If someone uses the incorrect extinguisher, act quickly and safely:

Stop using the extinguisher and move away if the fire grows or becomes uncontrolled.

Raise the alarm so others can evacuate.

Call the fire and rescue service immediately; tell them whether an extinguisher was used and what type it was.

Do not re-enter the area until the incident is declared safe.

After the incident, record the event in your fire logbook and review training, signage and equipment placement to prevent repetition.

Recording and reviewing incidents also demonstrates to enforcement bodies and insurers that you took appropriate post-incident action.

How to prevent using the wrong type: practical steps for responsible persons

Prevention focuses on the three pillars of fire safety management: assessment, provision and training.

Assessment: Review the fire risk assessment annually or when you change processes or layout. Ensure it identifies the likely fire classes and recommends extinguisher types accordingly.

Provision: Supply extinguishers that match risks and standards. Keep them serviced by competent, BAFE-certified technicians and carry out monthly visual checks on-site. Total Safe’s maintenance and servicing pages explain required frequencies and what a professional service includes. Fire extinguisher maintenance guidance.

Training: Provide role-specific instruction for nominated staff and general awareness for all employees. Ensure training covers identifying extinguisher markings and safe decision-making about when not to fight a fire.

Together, these steps reduce the chance of someone using the wrong extinguisher and improve overall safety.

Special environments and tricky scenarios

Certain settings need extra care. For kitchens and catering areas, wet chemical extinguishers and fire blankets are the primary defences. Do not use CO2 or powder on deep-fat cooking fires; they will not control the oil and may spread it.

For server rooms and data centres, CO2 or clean agent systems avoid residue that damages equipment. Dry powder will protect people but can ruin sensitive electronics.

For workshops and petrol forecourts, flammable liquids and fuel vapours require foam or specialist agents; in some cases only trained fire service response is acceptable. Always let your fire risk assessment guide the choice.

Replacing extinguishers and managing life cycles

Extinguishers have service intervals and working lives. For example, certain CO2 units require replacement after a decade; others are condemned after five years depending on type and manufacturer’s guidance. Regular servicing will flag condemned units and replace them before they fail in an emergency.

Keeping records in a fire logbook helps you and your servicing provider track expiry dates, maintenance history and remedial works. If you need a full-site review, Total Safe can conduct audits, replacement and installation to make sure your provision remains compliant and practical.

Conclusion and recommended next steps

Using the wrong type of fire extinguisher increases danger, can spread fire and may have legal and insurance consequences. In short, the right extinguisher in the right place, combined with clear signage and staff training, will dramatically reduce risk.

Recommended immediate actions:

Review your fire risk assessment and confirm extinguisher suitability.

Check that extinguishers are serviced and not past their service life.

Run or schedule refresher training for staff who may be expected to use extinguishers.

Update signage and place extinguishers where they are accessible but not too close to the hazard.

If you would like professional help with any of these steps, Total Safe offers risk assessments, extinguisher servicing and training to ensure your building and people remain safe and compliant.

FAQ

Q: What should I do if someone uses a water extinguisher on a cooking oil fire?

A: Evacuate the immediate area, raise the alarm, call the fire and rescue service and do not attempt further firefighting. Water on oil causes splashing and rapid spread.

Q: Can a CO2 extinguisher be used on electrical equipment?

A: Yes, CO2 is suitable for many electrical fires because it leaves no conductive residue; however, assess the surrounding risks and ventilate the area afterwards.

Q: How often must fire extinguishers be serviced?

A: Portable extinguishers should receive a professional service at least once every 12 months, with monthly visual checks by the responsible person. Professional servicing should be carried out by a competent, BAFE-certified technician.

Q: Are multipurpose extinguishers a safe option for general workplaces?

A: Multipurpose extinguishers may cover common risks, but they do not suit every scenario. Kitchens, petrol areas and specialised workshops usually require dedicated extinguisher types.

Q: Where can I find official guidance on suitable extinguisher types?

A: Authoritative guidance for small non-domestic premises and legal duties appears on GOV.UK and the HSE, which explain where extinguishers are needed and which types suit common risks. GOV.UK guide for persons with duties under fire safety law and HSE general fire safety guidance.