The zones can indi-
cated indicator board situated in, for example, supervisor’s office
or the main reception area.50.
2.
Larger buildings must divided into zones that the location the fire
can quickly identified the emergency services. Bells, hooters sirens may used
but any one installation they must all the same type. 14.
. Examples of
sounders are shown Fig.
Fire alarm design considerations
Since all fire alarm installations must comply with the relevant statutory
regulations, good practice recommends that contact made with the
local fire prevention officer the design stage order identify any par-
ticular local regulations and obtain the necessary certification.
A fire alarm installation may linked the local fire brigade’s control
room the telecommunication network, the permission the fire
authority and local telecommunication office obtained.Basic Electrical Installation Work
334
Sounders
The positions and numbers sounders should such that the alarm can
be distinctly heard above the background noise every part the prem-
ises. Standby battery supplies should capable maintaining the system
in full normal operation for least 24h and, the end that time, be
capable sounding the alarm for least 30min. Each zone should confined one storey, except where the total
floor area the building does not exceed 300m2
. the sound-
ers are arouse sleeping persons then the minimum sound level should
be increased 75dB the bedhead.
The electricity supply the fire alarm installation must secure the
most serious conditions.
The supply should exclusive the fire alarm installation, fed from a
separate switch fuse, painted red and labelled, ‘Fire Alarm Not Switch
Off’.
At least one fire alarm sounder will required each zone, but all sound-
ers the building must operate when the alarm activated.
4.
Definition
The positions and numbers sound-
ers should such that the alarm can
be distinctly heard above the back-
ground noise every part the
premises. practice the most reliable supply the mains
supply, backed ‘standby’ battery supply case mains failure. Each zone should single fire compartment. The sounders should produce minimum 65dB, 5dB above
any ambient sound which might persist, for more than 30s. Each zone should not have floor area excess 2000m2
.50
Typical fire alarm sounders. This means that the
walls, ceilings and floors are capable containing the smoke and fire.
In selecting the zones, the following rules must considered:
1. Normal speech about 5dB. Staircases and very small buildings should treated one zone.
The main sounders may silenced authorized person, once the
general public have been evacuated from the building, but the current
must diverted supervisory buzzer which cannot silenced until
the system has been restored its normal operational state.
FIGURE 14.
3
