Improved Audibility
The effectiveness of Category LD2 and LD3 systems can be
significantly enhanced if an additional Smoke Alarm (interconnected)
is installed in the master bedroom. This will help ensure that a
responsible person will quickly be alerted to a fire and can arrange for
an orderly evacuation of children and other vulnerable occupants.

2.3 Grade D, E & F Systems

The mains powered Smoke and Heat Alarms with battery back-up
covered by these instructions are suitable for Grade D, E & F Systems.
A Grade D system is needed for:
- new or materially altered dwellings, up to three-storeys, with no floor
over 200m2
- existing dwellings with poor structural fire precautions, up to three
storeys, with no floor over 200m2
- Houses in Multiple Occupation (HMOs) of one or two-storeys, with
no floor over 200m2
- Individual dwellings units of two or more rooms in HMOs
Check that a Grade D system is adequate for the dwelling into which
the system is being installed.
3. POSITIONING ALARMS
The locations must comply with applicable building
regulations.
Hot smoke rises and spreads out, so a central ceiling position
is the preferred location.The air is “dead” and does not move in
corners, therefore Smoke & Heat Alarms must be mounted
away from corners.Place the unit:
- At least 0.3m away from walls.See Figure 1.
- At least 0.3m from any light fitting or decorative object which
might obstruct smoke / heat entering the Alarm.
(Smoke Alarms should be located directly on the ceiling or, if not
possible, up to 575mm below it.Heat Alarms should be located directly
on the ceiling or, if not possible, up to 125mm below it).

Sloping Ceiling

In areas with sloping or peaked ceilings install the
Smoke/Heat Alarm 90cm from the highest point measured
horizontally (see Figure 2), because “dead air” at the apex
may prevent smoke from reaching the unit.
0.9m
0.3m

Figure 1 Figure 2

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