I cannot now quote properly so have respond to ABs point about deviating from bench marks this way.
I cannot highlight the key areas in this text as I cannot now scroll down to and edit any text below the window. (Not very technical explanation) Is the website in meltdown?.
In short the guide allows for discretion so therefore using discretion is not a failure to follow guidance.
The BS does provide for deviation as contained in the following. A5 in particular.
4 Need for a fire alarm system
4.1 CommentaryThe need for a fire alarm system in any specific building will normally be determined by the authority
responsible for enforcing fire safety legislation in that building and/or by a fire risk assessment carried out by the owner, landlord, occupier(s) or employer(s), as appropriate. In general, it is appropriate to install some form of fire alarm system in virtually all buildings, other than very small premises that are relatively open-planned so that any fire will be quickly detected by occupants, who will be able to warn others by word
of mouth or simple mechanical devices such as hand-operated bells.
Manual fire alarm systems are often sufficient to satisfy legislation in workplaces in which no one sleeps.
Automatic fire detection is usually required by legislation to supplement the manual system in premises in
which people sleep. Automatic fire detection might also be necessary to satisfy legislation under the following circumstances:
a) where the automatic fire detection forms part of a fire engineering solution;
b) where fire protection systems, such as door closing facilities or smoke control systems, are to be operated
automatically in the event of fire;
c) where the low level of occupancy of a building, or part of a building, is such as to create the potential
for fire to prejudice means of escape by occupants before they are aware of the fire.
BS 5839-1:2002+A2:2008
10 © BSI 2008
Section 1
Automatic fire detection is also commonly used to protect property by ensuring the early attendance of the
fire service, as a result of the summoning of the brigade by occupants of the building or by transmission of
fire alarm signals to an alarm receiving centre from where the fire service will be summoned. Automatic fire
detection systems might, therefore, be required or recommended by the property insurers.
The early detection of fire by automatic means, and rapid summoning of the fire service, is also important
in premises in which people cannot readily be evacuated immediately in the event of fire (e.g. hospitals).
4.2 Recommendations
The following recommendations are applicable.
a) Where there is uncertainty regarding the need for a fire alarm system, or the Category of system that
should be used (see Clause 5) reference should be made, by the developer, potential purchaser or user, to
one or more of the following:
1) relevant part of BS 5588;
2) guidance documents that support fire safety legislation;
3) any authority responsible for enforcing fire safety legislation that applies to the premises;
4) the property insurer;
5) any relevant fire risk assessment.
b) The purchaser or user should ensure that the designer of a fire detection and alarm system is
adequately appraised of the objectives of the system and any relevant requirements of enforcing
authorities and insurers.
