Fire extinguishers at work: calculating the number, inspection and mounting
How many fire extinguishers a company needs depends on floor area and fire risk. How to calculate extinguishing units under the German technical rule ASR A2.2, choose the right extinguishers and organise inspections.
Last updated on 8 min readAMS Go editorial team
Key points at a glance
- The number of fire extinguishers is governed by ASR A2.2: the floor area determines the required extinguishing units (Löschmitteleinheiten, LE), and the extinguishers together must reach at least this value.
- With normal fire risk, up to 50 m² requires 6 LE, up to 100 m² 9 LE and up to 1,000 m² 36 LE; each further 250 m² adds 6 LE. With increased fire risk, this is not enough.
- Fire extinguishers must be easy to reach – no more than 20 metres walking distance from any point – and inspected by a competent person at least every two years.
- This also includes signs, enough fire wardens and instruction on how to use fire extinguishers.
Who must provide fire extinguishers
Every employer must take precautions for firefighting (Section 10 of the Occupational Safety and Health Act, Annex 2.2 of the Workplaces Ordinance). The technical rule for workplaces ASR A2.2 “Measures against fires” sets out what this looks like: how many fire extinguishers a company needs, where they hang and how they are inspected.
ASR A2.2 distinguishes between normal and increased fire risk. The risk is normal if combustible materials are present but a fire spreads only slowly in its initial phase – typical of offices or workshops with little combustible material. It is increased, for example, in storage areas with highly flammable substances, in paint shops or with a lot of combustible dust.
Calculating the number of fire extinguishers
Fire extinguishers are not counted by number but by extinguishing units (LE). For normal fire risk, ASR A2.2 specifies:
Floor area up to 50 m²
Extinguishing units6 LE
Floor area up to 100 m²
Extinguishing units9 LE
Floor area up to 200 m²
Extinguishing units12 LE
Floor area up to 300 m²
Extinguishing units15 LE
Floor area up to 400 m²
Extinguishing units18 LE
Floor area up to 500 m²
Extinguishing units21 LE
Floor area up to 600 m²
Extinguishing units24 LE
Floor area up to 700 m²
Extinguishing units27 LE
Floor area up to 800 m²
Extinguishing units30 LE
Floor area up to 900 m²
Extinguishing units33 LE
Floor area up to 1,000 m²
Extinguishing units36 LE
each further 250 m²
Extinguishing units+ 6 LE
How many LE a fire extinguisher provides depends on its fire rating, which is printed on the device – for example 21A or 43A:
Fire rating (class A) 13A
Extinguishing units4 LE
Fire rating (class A) 21A
Extinguishing units6 LE
Fire rating (class A) 27A
Extinguishing units9 LE
Fire rating (class A) 34A
Extinguishing units10 LE
Fire rating (class A) 43A
Extinguishing units12 LE
Fire rating (class A) 55A
Extinguishing units15 LE
With increased fire risk, the basic equipment is not enough: additional extinguishers, special extinguishing agents or further measures according to the risk assessment are then required.
Choosing the right fire extinguisher
The extinguishing agent must match the fire class. The wrong extinguisher can be ineffective or even dangerous – water on burning fat causes a fat explosion.
A
Burning materialssolids such as wood, paper, textiles, plastics
Suitable agentswater, foam, ABC powder
B
Burning materialsliquids or liquefying materials such as petrol, oil, paints, wax
Suitable agentsfoam, ABC or BC powder, carbon dioxide
C
Burning materialsgases such as propane, natural gas, hydrogen
Suitable agentsABC or BC powder
D
Burning materialsmetals such as aluminium and magnesium
Suitable agentsmetal fire powder
F
Burning materialscooking oils and fats in kitchens
Suitable agentsfat fire extinguisher
- Offices and administration: foam extinguishers – effective on class A and B fires and without the heavy contamination caused by powder
- Server rooms and electrical equipment: carbon dioxide – leaves no residue; watch out for the risk of suffocation in small rooms
- Workshops and storage: foam or ABC powder, depending on fire loads
- Kitchens and canteens: an additional fat fire extinguisher
Mounting and marking fire extinguishers
- clearly visible and easy to reach, preferably along escape routes, at exits and near particular hazards
- no more than 20 metres actual walking distance from any point to the nearest fire extinguisher
- handle height between 0.80 and 1.20 metres
- marked with the “fire extinguisher” fire safety sign under ASR A1.3, recognisable from a distance
- protected from weather and damage and not obstructed
Inspection: at least every two years
Fire extinguishers must be inspected and maintained by a competent person at least every two years (ASR A2.2, DIN 14406-4). With heavy exposure to weather, vibration or dirt, shorter intervals may be needed. The inspection is noted on a label on the extinguisher.
Used or damaged fire extinguishers are repaired or replaced immediately – even if they were only used briefly. Between inspections, a quick look during every safety inspection pays off: is the extinguisher in its place, is it accessible, is the seal intact?
Fire wardens and instruction
Fire extinguishers are only useful if someone can operate them. ASR A2.2 therefore requires a sufficient number of fire wardens – usually 5 per cent of employees, more with increased fire risk. All employees are also instructed on using fire extinguishers and what to do in case of fire, ideally with a practical extinguishing exercise.
Checklist: fire extinguishers at work
- Fire risk assessed per area: normal or increased
- Extinguishing units per floor area calculated under ASR A2.2
- Fire extinguishers chosen to match the fire class
- No more than 20 metres walking distance to the nearest extinguisher
- Handle height 0.80 to 1.20 metres, fire safety sign in place
- Inspection by a competent person at least every two years
- Fire wardens appointed and trained
- Employees instructed on using fire extinguishers
- Fire extinguishers checked for accessibility during every inspection
Free templates for this guide
As PDF and Excel, no sign-up – free to use in your own company.
Frequently asked questions
How many fire extinguishers does an office need?
It depends on the floor area. An office of 200 m² with normal fire risk needs 12 extinguishing units under ASR A2.2 – for example two foam extinguishers of 6 LE each. In addition, the walking distance to the nearest extinguisher may not exceed 20 metres.
How often must fire extinguishers be inspected?
At least every two years by a competent person, and immediately after every use or damage.
What are extinguishing units?
A unit used to compare the extinguishing capacity of different fire extinguishers. An extinguisher with a 21A rating equals 6 LE, one with 43A equals 12 LE. ASR A2.2 specifies how many LE are needed per floor area.
At what height must fire extinguishers be mounted?
So that the handle is between 0.80 and 1.20 metres above the floor. This way, shorter people can also easily take the extinguisher out of its bracket.
May I inspect fire extinguishers myself?
The regular inspection is carried out by competent persons according to DIN 14406-4, in practice usually by specialist fire protection companies. Visual checks during inspections – location, accessibility, seal, inspection label – can be carried out by your own employees.
Terms from the glossary
This guide gives a general overview of German occupational safety law and does not replace legal advice. The regulations in force and the rules of the statutory accident insurance institutions are authoritative.
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