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L1 or L3 design question

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Quick design conundrum...


We have had a tender through to quote a L3 system in a 100mx100m warehouse with internal offices at the front (the standard type of warehouses nowadays, sheds with an office). 


The way I interpret L3 is that all escape routes must be covered etc., my question is - would the bulk warehouse be classed as an escape route? I'm presuming so, if so the L3 is very close to an L1 except a cleaner cupboard or two, but even in a cleaner cupboard scenario, the argument is there to be had that EVERY room is an escape route if it has a potential of having people in at any one time? 


Someone must know more on this than me & there must be a explanation, I cant get my head around that every room or corridor will be an escape route in any building or has the potential to be...? I don't see a huge difference at all between L1 & L3?



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5.1.3 Category L systems
Category L systems are automatic fire detection and fire alarm systems intended for the protection of life. They are
further subdivided into:
a) Category L1: systems installed throughout all areas of the building.
The objective of a Category L1 system is to offer the earliest possible warning of fire, so as to achieve the
longest available time for escape;
b) Category L2: systems installed only in defined parts of the building.
A Category L2 system ought to include the coverage necessary to satisfy the recommendations of this standard
for a Category L3 system; the objective of a Category L2 system is identical to that of a Category L3 system,
with the additional objective of affording early warning of fire in specified areas of high fire hazard level and/
or high fire risk;
c) Category L3: systems designed to give a warning of fire at an early enough stage to enable all occupants, other
than 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 gases;
NOTE 1 To achieve the above objective it is normally necessary to install detectors in rooms which open onto
an escape route (see 8.2).
d) Category L4: systems installed within those parts of the escape routes comprising circulation areas and
circulation spaces, such as corridors and stairways

Peter Robinson



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d) MCPs should be located on escape routes and, in particular, at all storey exits and all exits to open
air that lead to an ultimate place of safety (whether or not the exits are specifically designated as
fire exits).
Those located at storey exits may be sited within the accommodation or on the landing of a
stairway to which the storey exit gives access (see Figure 6). In multi-storey buildings with
phased evacuation, in which only a limited number of floors are evacuated at one time, only
the former option applies; under these circumstances, MCPs should not be located on stairway
landings, as persons travelling down the stairway might operate an MCP several floors below
that on which a fire is located, resulting in evacuation of inappropriate areas.
e) Distribution of MCPs should be such that no one need travel more than 45 m [except where
20.2f) applies] to reach the nearest MCP, measured along the route that a person would actually
follow taking into account the layout of walls, partitions and fittings. If, at the design stage, the
final layout of the premises is unknown, the maximum straight line distance between any point
in the building and the nearest MCP should not exceed 30 m [except where 20.2f) applies]; after
final fit out of the premises, the limit of 45 m should still then apply.
NOTE 4 These distances are arbitrary, but reflect the maximum acceptable distances between any point and
the nearest storey exit commonly applied to many premises.
f) The figures of 45 m and 30 m recommended in e) should be reduced to 25 m and 16 m,
respectively, in the following circumstances:

Peter Robinson



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