Electrical Contracting News (ECN) May 2016 | Page 43

SPECIAL FEATURE

FIRE DETECTION & SECURITY

POSITION OF ALARMS
The positioning of alarms is vitally important in order to ensure effective detection in the
event of a fire incident. It is the responsibility of the contractor or installer to make sure
the alarm locations comply with any applicable building regulations, but below is a basic
guide to follow.

Smoke alarms
Flat ceiling:
• Site at least 300mm from walls.
• Site at least 300mm from any light fittings.
• Site as centrally as possibly.
Flat ceilings with beams:
• Site at least twice the depth of the beam away. Eg. 150mm beam depth, site the
alarm at least 300mm away from the beam.
• If the depth of the beam is greater than 10 per cent of the ceiling height, the beam
should be treated as a wall (alarms need to be on either side of the beam).
Pitched roof:
• Site at no more than 600mm vertically below apex.
Wall mounted:
•T
 he top of the detection element should be between 150mm and 300mm below
the ceiling.
• Site at least 300mm from a perpendicular wall.

Multi-sensing

More and more contractors and installers are
moving towards the use of multi-sensing alarms.

This can be seen clearly in recent
statistics from the Department for
Communities and Local Government that
revealed a smoke alarm was present in 19
per cent of all dwelling fires in the UK but
did not operate.

Optical
Optical smoke alarms are more responsive
to fires that begin with a long period of
smouldering, such as sofa fires