Potter Releasing Systems User Manual
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Heat Detectors Only
On ceilings 10 ft. to 30 ft.
high, heat detector spacing
shall be reduced.
b. For beam depths greater than or equal to 10 percent of the ceiling height (0.1 H), spacing shall be in
accordance with 17.7.3.2.4.2
4. For corridors 15 ft (4.6 m) in width or less having ceiling beams or solid joists perpendicular to the corridor
length, the following shall apply:
a. Smooth ceiling spacing shall be permitted.
b. Location of spot-type smoke detectors on ceilings, sidewalls, or the bottom of beams or solid joists
5. For rooms of 900 ft2 (84 m2) or less, the following shall be permitted:
a. Use of smooth ceiling spacing
b. Location of spot-type smoke detectors on ceilings or on the bottom of beams
NFPA 72 2010, 17.7.3.2.4.2 See NFPA 72 2010 17.7.3.2..3 and 17.7.3.2.4.4
Sloped/Peaked Ceilings
Sloped Ceiling - Having a slope of more than 1.5 inches per foot
Peaked Ceiling - Having a slope of more than 1.5 inches per foot in two directions from its highest point. May
include domed or curved ceilings.
To determine if a ceiling is sloped or peaked:
Divide the difference between the height of the low wall and the highest point of the ceiling in inches by the
width of the building in feet. If the answer is 1.5 or less, the ceiling is considered flat. (Highest point of ceiling
in inches) minus (top of low wall in inches) divided by (width of building in feet).
Smoke and heat detector placement on sloped ceilings
Make all measurements parallel to the floor, not along the ceiling. Locate the point on the ceiling which is 3 ft.
from the high sidewall. Locate the first detector anywhere within that three feet, except the four inches nearest
the wall. The remaining detectors shall be located in the remaining ares on the basis of the horizontal projection
of the ceiling, spaced in accordance with the type of construction.
Smoke and heat detector placement on peaked ceilings
Detectors shall first be spaced and located within 3 ft of the peak, measured horizontally. The number and spacing
of additional detectors, if any, shall be based on the horizontal projection of the ceiling NFPA72, 2010 17.7.3.3.
Raised Floors and Suspended Ceilings
Spaces beneath raised floors and above suspended ceilings shall be treated as separate rooms for smoke detector
spacing purposes. Detectors installed beneath raised floors or above suspended ceilings, or both, including
raised floors and suspended ceilings used for environmental air, shall not be used in lieu of providing detection
within the room. NFPA72, 2007 5.7.3.7
To minimize dust contamination, smoke detectors, where installed under raised floors, shall be mounted only in
an orientation for which they have been listed. NFPA72, 2007 5.7.3.2.2
Protection During Construction
Where detectors are installed for signal initiation during construction, they shall be cleaned and verified to be operating
in accordance with the listed sensitivity, or they shall be replaced prior to the final commissioning of the system.
Where detectors are installed but not operational during construction, they shall be protected from construction
debris, dust, dirt, and damage in accordance with the manufacturer’s recommendations and verified to be operating
in accordance with the listed sensitivity, or they shall be replaced prior to the final commissioning of the system.
Where detection is not required during construction, detectors shall not be installed until after all other
construction trades have completed cleanup.
NFPA72, 2010 17.7.1.11
Ceiling Height
% of Listed
Spacing
Above
Up To
0
10
100%
10
12
91%
12
14
84%
14
16
77%
16
18
71%
Ceiling Height
% of Listed
Spacing
Above
Up To
20
22
58%
22
24
52%
24
26
46%
26
28
40%
28
30
34%