Summary

Fire extinguishers are required by law in most commercial premises under the Regulatory Reform (Fire Safety) Order 2005 (FSO). Domestic properties are not legally required to have extinguishers, but housing associations, HMOs (Houses in Multiple Occupation), and all commercial premises must have an adequate provision.

For tradespeople working on commercial fit-outs, refurbishments, or HMOs, understanding the fire class system, correct placement, signage, and maintenance schedule prevents the client's fire risk assessment from identifying non-compliance. This article covers the selection, placement, and inspection requirements under BS 5306.

Key Facts

  • Fire classes (BS EN 2) — Class A: solid combustibles (wood, paper, textiles); Class B: flammable liquids (petrol, oils, paints); Class C: flammable gases (LPG, propane); Class D: combustible metals (magnesium, aluminium powder); Class F: cooking oils and fats
  • Electrical fires — not a class in their own right; electrical equipment fires start with electrical ignition but the fire is Class A (when it spreads to solids) or B (flammable liquids); CO2 extinguishers are rated for use on electrical equipment; do NOT use water or foam on live electrical equipment
  • Colour coding (BS EN 3) — all extinguisher bodies are red; a coloured band/panel (up to 10% of body area) identifies the agent: red = water; cream = foam; blue = dry powder; black = CO2; yellow = wet chemical; no band/panel (red only) = water spray
  • Water extinguisher (red) — Class A only; uses a 9-litre water jet; NOT suitable for Class B or electrical fires; risk of spreading burning liquid and electric shock
  • Foam extinguisher (cream) — Class A and B; AF foam; suffocates liquid fires and cools solids; NOT suitable for electrical (current models are labelled for certain electrical use after a 1m conductivity test)
  • Dry powder (blue) — Class A, B, C, and some Class D; highly effective but poor visibility, leaves residue, damages electronics; specialist use; some all-purpose versions labelled ABC
  • CO2 extinguisher (black) — Class B and electrical equipment; no residue; vaporises; suitable for server rooms and electrical panels; the CO2 cloud is a suffocation risk in confined spaces; do not use in small enclosed areas
  • Wet chemical (yellow) — Class F (cooking oils); mandatory in commercial kitchens; also effective on Class A; designed to saponify burning fat and cool it below re-ignition temperature
  • BS 5306-3:2017 — Code of practice for selection, installation and maintenance of portable fire extinguishers; governs servicing intervals
  • Annual inspection — BS 5306-3 requires visual inspection by a competent person every 12 months; checks include: pressure indicator; tamper seal intact; condition of body, hose, nozzle; correct location and signage; weight (CO2)
  • 5-year extended service — internal examination of powder extinguishers at 5 years; discharged and refilled
  • 10-year hydraulic pressure test — water and foam extinguishers at 10 years; tested to 1.5× working pressure; if failed, replace

Quick Reference Table

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Extinguisher Type Colour Code Fire Classes NOT Suitable For Typical Size
Water Red body + red band A B, C, D, F, electrical 6L, 9L
Water (mist) Red body + white band A, some B, electrical C, D, F 6L
Foam (AFFF) Red + cream band A, B C, D, F, electrical (except tested units) 6L, 9L
Dry powder (ABC) Red + blue band A, B, C D, F, electrical (residue) 1kg, 2kg, 6kg, 9kg
CO2 Red + black band B, electrical A (limited), C, D, F 2kg, 5kg
Wet chemical Red + yellow band A, F B, C, D 6L

Placement Guide (BS 5306-3)

Premises Type Recommended Provision Travel Distance to Extinguisher
Single-storey office 1× 2kg CO2 + 1× 6L foam per 200m² Max 30m
Multi-storey building Minimum 1 extinguisher per floor Max 30m
Commercial kitchen 1× wet chemical (Class F) mandatory Adjacent to cooking equipment
Server room CO2 or gaseous system Room specific
Warehouse (Class A risk) 9L water or foam at 25m travel Max 25m (higher risk)
Vehicle (commercial) 1× 1kg or 2kg dry powder In cab or vehicle body

Detailed Guidance

Selecting the Right Extinguisher for the Premises

The fire risk assessment (required under the FSO for all non-domestic premises) drives extinguisher selection. Key questions:

What combustibles are present?

  • Paper, textiles, wood, furniture → Class A → water or foam
  • Flammable liquids, paints, solvents → Class B → foam or dry powder
  • Cooking oils → Class F → wet chemical (mandatory for commercial kitchens)
  • Electronics → no class but CO2 is preferred

Is the area small and enclosed? CO2 extinguishers in very small rooms create a suffocation risk. In enclosed spaces below approximately 10m³, consider water mist or wet chemical as an alternative.

What is the occupant risk? Dry powder reduces visibility when discharged and irritates airways — in occupied buildings with vulnerable people (care homes, schools), CO2 or water mist is preferred over dry powder despite its effectiveness.

Standard provision for a small office or commercial premises:

  • One 2kg CO2 for electrical equipment (copiers, computers)
  • One 6-litre foam for general fire risk (paper, furniture)
  • This covers Classes A, B, and electrical risk adequately for a standard office environment

Installation and Signage

Wall mounting: Extinguishers must be wall-mounted or on a floor stand. BS 5306-3 recommends mounting so the handle is no more than 1.0–1.5m above the floor (accessible to all users). Mount on a purpose-made bracket; do not rest on the floor without a stand (risk of being knocked over and not visible at low heights).

Signage: Extinguishers must have a location sign (rectangular with red background, pictogram showing person with extinguisher, and "FIRE EXTINGUISHER" text) above or near the extinguisher. In long corridors or around corners, directional signs are required.

Spacing: The maximum travel distance to an extinguisher from any point in a room should not exceed 30m (or 25m for higher-risk areas). For a standard open-plan office, this means one provision per 200–300m² floor area.

BS 5306-3 Maintenance Schedule

Monthly check (occupant/responsible person):

  • Extinguisher in correct location
  • Tamper seal intact
  • Pressure gauge in green zone (if fitted)
  • Body not visibly damaged or corroded
  • No obstruction to access

Annual service (competent person): The annual service must be carried out by a fire extinguisher engineer (British Fire Consortium, Fire Industry Association, or equivalent). The service includes:

  • Visual inspection of all external surfaces
  • Check of the discharge mechanism
  • Weight check for CO2 (to ensure charge has not leaked)
  • Replacement of tamper seal and safety pin
  • Label with service date and engineer's ID

5-year extended service (dry powder, CO2):

  • Discharge and internally inspect
  • Refill to manufacturer specification
  • Pressure test (5-year test, not hydraulic — a functional test and internal inspection)

10-year hydraulic test (water, foam):

  • Pressure test to 1.5× working pressure (typically 22.5–25 bar)
  • If body shows any defect, replace the extinguisher
  • Repaint and relabel after test

Disposal: Old extinguishers should not be placed in general waste. The pressurised container is a hazard. Most fire extinguisher service companies will collect and dispose of old units. CO2 cylinders must be handled carefully — if the cylinder is discharged, it can be recycled; pressurised cylinders are a puncture hazard.

HMO Requirements

For Houses in Multiple Occupation (HMOs), the local authority's licensing conditions specify fire safety requirements. Typical requirements include:

  • Minimum 1kg CO2 extinguisher in the kitchen
  • Heat detector in the kitchen
  • Smoke alarms on all floors
  • Some local authorities require thumb-turn or lever locks on fire doors
  • LACORS Housing Fire Safety guidance is the reference document

Fire extinguisher provision in HMOs varies by local authority and the category/size of HMO. Always check the specific licensing conditions.

Frequently Asked Questions

Can my customer keep an extinguisher at home?

Yes — domestic extinguishers are sold in DIY stores and online. A 1kg or 2kg dry powder or a 2-litre foam unit is suitable for a domestic kitchen or garage. They do not require annual servicing by law for domestic use (but it is recommended). Advise customers to place the extinguisher away from the most likely fire source (e.g., not next to the hob where a cooker fire would prevent reaching it).

A customer's kitchen extinguisher is a dry powder type. Should I replace it?

For a commercial kitchen, yes — dry powder is not suitable for cooking oil fires (Class F). It does not cool the fat and the oil may re-ignite. A wet chemical extinguisher is mandatory for commercial cooking equipment. For a domestic kitchen, a dry powder unit provides some protection but a foam or water mist unit is safer for general household fire risks.

The fire extinguisher label says it was last serviced 3 years ago. Does it need annual servicing?

Yes. BS 5306-3 requires annual service for all premises extinguishers. A 3-year-old service date means the extinguisher has missed two annual services and is non-compliant. It should be serviced immediately. If the premises is subject to a fire risk assessment (all commercial premises), non-compliant extinguishers are a deficiency that must be corrected.

Regulations & Standards

  • Regulatory Reform (Fire Safety) Order 2005 (FSO) — fire safety duties for non-domestic premises; fire risk assessment requirement

  • BS 5306-3:2017 — Selection, installation and maintenance of portable fire extinguishers; UK code of practice

  • BS EN 3 — Portable fire extinguishers; European standard; colour coding

  • BS EN 2 — Fire classification system; Classes A, B, C, D, F

  • LACORS Housing Fire Safety — Guidance for HMOs and multi-occupied residential properties

  • Fire Industry Association: Extinguisher Guidance — Technical guidance and inspector registration

  • HSE: Fire Safety — Workplace fire safety; FSO summary

  • NIFES Fire Safety — UK fire safety guidance and training

  • intumescent seals — Fire stopping for penetrations and door seals

  • part b fire — Building Regulations Part B; fire safety in construction

  • site setup — Fire safety on construction sites

  • public liability — Insurance implications of fire safety compliance