8
9
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www.espuk.com
Never mount devices closer than twice the depth of light fittings.
Voids less than 800mm in height need not have independent coverage, unless
fire or smoke is able to spread from one area to another through the void or risk
assessment shows AFD (Automatic Fire Detection) to be necessary.
For ceilings that feature an apex: as long as the height of the apex from the
rest of the ceiling is less than 150mm for heat detectors or less than 600mm
for smoke detectors then these can be treated the same as flat ceilings. For
higher apexes, a device should be installed at the highest point. The distance to
adjacent devices can be increased by 1% per degree of angle of the roof up to a
maximum of 25%.
Detector Type
Ceiling Height (m)
General Limits
Maximum
Heat RoR
9.0
10.5
Heat Fixed
7.5
12.5
Point Smoke Detector
10.5
12.5
Aspirating Smoke Detection Class C with 5 holes
15
18
Aspirating Smoke Detection Class C with 15 holes
25
28
Aspirating Smoke Detection Class B with 5 holes
40
43
Optical Beam Normal Sensitivity
25
28
Optical Beam Enhanced Sensitivity
40*
43
*Supplemented detection recommended unless risk of stratification is minimal.
SMOKE DETECTORS
100mm
<200mm
(500mm for detectors)
Light fitting
>800mm
Apex < 150mm
Heat Detector
Standard Spacing
Extended Spacing
Apex < 600mm
Smoke Detector
Apex > 150mm
Heat Detector
Apex > 600mm
Smoke Detector
