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Guide to BS5839 PT1

Early /smoke detection and notification saves lives and property!

Most commercial and industrial premises are nowadays required to have a fire alarm system designed and installed to BS589. The system is better described as a fire detection & alarm system, as it’s primary function is firstly to detect a fire or fire condition, and secondly to sound audible alarms in all parts of the building.

 At it’s simplest, the system may be operated by a Manual Break Glass unit (called a manual system). At it’s most complex, the system may have very many different types of smoke, heat and other types of detectors are spread throughout the building and possibly linked with other buildings and central stations.

It is essential that fire alarms are correctly designed, specified, installed and maintained.

The system design and installation should always be agreed with all parties including the local fire officer, the local district building officer, Insurers, site fire officers.

Systems for protecting life

Type M – Manual system – A system that relies upon manual operation of a break glass call point by building occupants. When operated the fire alarm sounders operate.

Manual call points at all fire exits ad within 30mtrs, 16mtrs from a kitchen. Alarm sounders to achieve 65dB in all rooms and 75dB at the bed head.

Type L1 – As with M and automatic detection installed throughout the building, including ceiling voids over 800mm, but the following rooms or areas need not be protected if they are low fire risk: 

  • (Not to be protected) Toilets, shower rooms and bathrooms (if no risk)
  • Small cupboards (typically less than 1m squared)
  • Note, A riser in which there is fire resisting floor and ceiling may be treated as a cupboard  
  • Some shallow voids (less than 800mm in depth)

Type L2 – As M and automatic detection installed in defined parts of the building – the rooms or areas protected should comply with the following recommendations:

  • All escape stairways
  • All corridors
  • Any other areas that form part of the common escape routes
  • Any rooms adjoining the escape corridors (excluding toilets, shower rooms, bathrooms and small cupboards)
  • High risk areas e.g. Kitchen, Boiler rooms

Type L3 – As M – systems designed to give early warning of a fire at an early enough stage to enable occupants, other then possibly those in the room of fire origin, to escape safely, before the escape routes are impassable owing to the presence of fire, smoke or toxic smoke.

The following recommendations: 

  • All escape Stairways
  • All corridors
  • All rooms opening onto the escape corridor (excluding toilets, shower rooms, bathrooms and rooms of less than 4m in length if protected by fire resisting construction, including doors that separate these corridors from any other section of the escape routes)

Type L4 – As M – automatic detection installed within those parts of the escape routes comprising circulation areas and circulation spaces, such as corridors and stairways.

Type L5 – As M – systems in which protected area(s) and / or the location of detectors is designed to satisfy a specific objective (other than that of a category L1, L2, L3 or L4 system). For this type of system, the area protected must be listed on the commissioning certificate.

 Little black book of Fire Detection & Alarm Systems (want to know more, then just click)


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