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equipment to BS EN 54-2, and power
supply to BS EN 54-4, installed to BS
5839: Pt.1 with some minor
exceptions
• Grade B - Fire detection and alarm
system comprising fire detectors
(other than smoke alarms), fire alarm
sounders and control and indicating
equipment to either BS EN 54-2 (and
power supply to BS EN 54-4), or to
Annex C of BS 5839: Pt.6
• Grade C - System consisting of smoke
detectors and sounders (which may
be smoke alarms) connected to a
common power supply, comprising
normal mains and stand-by supply,
with central control equipment
• Grade D - System incorporating one
or more mains powered smoke alarms
(and heat alarms if required) each
with an integral stand-by supply
• Grade E - System of mains powered
smoke alarms (and heat alarms if
required) with no stand-by supply
• Grade F - System of one or more
battery powered smoke alarms (and
heat alarms if required)
The changes from the previous edition
are relatively small: Grade A & B now
refer to the latest European Standards
and there are minor changes in
requirements. Grade C now requires
central control of the system. Grades E,
D & F now have reference to heat
alarms in addition to smoke alarms.
Concerned by problems with battery
powered units in Grade F, the
prescriptive advice in the Code now
recommends a minimum five year
battery life and batteries that are
secured so that a special tool is
required to remove them for use in
tenanted single storey properties.
As the overwhelming number of
residential applications in the UK will fall
into the D to F categories, this is the
area on which this guide will naturally
focus. If you are particularly interested
in unusual grades of protection, you are
invited to look further at the relevant
clauses of the Code.
Of course, installers and specifiers may
install a system with greater safety
features than laid down in the letter of
the Code. For example, rather than a
Grade E system landlords might think it
prudent to install a Grade D system
instead. This is especially true
considering the many restrictions that
apply to the use of Grade E systems.
LEVELS OF PROTECTION
CATEGORIES OF SYSTEM
This was previously referred to as ‘type’
of system. It relates to the level of
protection afforded by the system.
Within the A - F grades defined earlier,
the Code identifies three different
categories of protection:
• LD1 - A system installed throughout
the dwelling, incorporating detectors
in all circulation spaces that form
part of the escape routes from the
dwelling, and in all rooms and areas
in which fire might start, other than
toilets, bathrooms and shower rooms
• LD2 - A system incorporating
detectors in all circulation spaces
that form part of the escape routes
from the dwelling, and in all rooms or
areas that present a high risk of fire
• LD3 - A system incorporating
detectors in all circulation spaces
that form part of the escape routes
from the dwelling
Apart from the change of name, there
are no changes to the ‘Categories’
from the previous version of the code.
It is noted that an LD3 type system is
intended to protect escape routes for
those not directly involved in the fire
and may not save the life of anyone in
the immediate vicinity of the fire.
The Code also features two grades of
protection for property - PD1 and PD2.
Briefly, PD1 offers comprehensive
coverage of all areas, while a PD2
system includes detectors in only those
areas where there has been judged a
fire risk. Only by quoting Grade and
Category can a meaningful and
effective alarm system be specified,
e.g. Grade D, Category LD2.
QUALITY & COMPATIBILITY
The quality of equipment installed is a
factor that needs to be carefully
considered. The Code states that, in
general, all components should conform
to relevant British Standards and should
have undergone type testing to those
Standards. Suppliers should preferably
have approval to a recognised quality
approval scheme such as the relevant BS
EN ISO 9000 series standard. If no British
Standards apply, reasonable care should
be taken that components are fit for the
purpose intended.
The Code recommends that all
individual system components should
be mutually compatible.
Conformance to the relevant British
Standard is no guarantee that the
components of a system will be
compatible. Consequently, this should be
confirmed at the design stage.
THE GRADE SYSTEM
Relates to system engineering not level
of protection.
BS 5839: Pt.6 grades fire detection
systems from Grade A down to Grade F.
Generally speaking, the greater the fire
risk and the more demanding the
application, the more comprehensive
the system needs to be.
• Grade A - Fire detection system
incorporating control and indicating