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GENERAL ELECTRICAL SPECIFICATION
Version 2014-2
Analogue addressable base units will be inclusive of alarm sounder and beacon elements
and shall be directly loop driven, each element will be separately addressable.
2.17.4.1 Optical Smoke Detectors
Smoke detectors shall fully meet the requirements of BS EN 54-1.
Smoke detectors shall be of the infra-red emitter/sensor type for detection of
smoke/vapour particles with two stage verification.
A light emitting diode shall be mounted in the side of the unit arranged to illuminate
when the detector is in an alarm condition.
The performance sensitivity of the smoke detectors shall be not more than 5%
obscuration at 1m.
The unit shall be constructed from white moulded plastic and provided with a mesh to
stop the ingress of large dust particles and insects, etc.
2.17.4.2 Optical Heat Detectors
The response curve for heat detectors shall conform to BS EN 54-1, with an operating
o
temperature of 58 C.
A light emitting diode shall be mounted in the side of the unit arranged to illuminate
when the detector is in an alarm condition.
2.17.5 Void Detection
Where ceiling voids exist that are 800mm in depth (or deeper), optical smoke detectors
shall be fitted within these voids with remote LED indicators fitted on the ceiling below.
In addition to the above, any beam within the void with a depth of 800mm (or greater)
shall be treated as a solid wall and extra detectors should be fitted to satisfy the
requirements of BS 5839-1 section 2 item 22.3 (J) and note 7.
2.17.6 Sounders
2.17.6.1 Conventional System - Bells
Alarm sounders shall comply with BS EN 54-3; 150mm diameter bells shall be provided as
necessary to meet the minimum alarm sound requirements of 65dB(A) or 5dB(A) above
ambient.
Alarm sounders will be complete with back plate and mounted on a flush conduit box.
Sounders shall generally be mounted at 200mm below the false ceiling and where
installed externally shall be of the weatherproof type.
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