# smoke detector spacing



## cda (Apr 14, 2010)

Looking for system smoke detector spacing requirements for thirty foot level

nfpa 72??

missing it if it is there.


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## Coug Dad (Apr 14, 2010)

Try the mfgr's specs.


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## FM William Burns (Apr 14, 2010)

Agree with CougDad and if you have not already, give Annex B some read for conderations to take into account with this height.


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## TimNY (Apr 15, 2010)

I think you're venturing into the realm of designed protection vs prescriptive.  These may be some applicable sections (per 2002 72):

5.4.4 Initiating devices shall be installed in a manner that provides accessibility for periodic maintenance.

5.7.1.4 The prescriptive requirements in this section shall be applied only where detectors are installed in ordinary indoor locations.

5.7.1.7 The selection and placement of smoke detectors shall take into account both the performance characteristics of the detector and the areas into which the detectors are to be installed to prevent nuisance alarms or improper operation after installation.

5.7.1.10 The effect of stratification below the ceiling shall be taken into account.  The guidelines in Annex B shall be permitted to be used.

The question I would ask before getting to spacing (you may have already asked it):

--are smoke detectors mounted 30' above the floor accessible?  Probably so in a warehouse situation where they have lifts.  Not so, imho, in a typical office building with a stair tower or a tall atrium.  This is an AHJ decision.   If not accessible, maybe beam-type is a better solution.

I don't think there is a one-size-fits-all answer.  I would look at the type of hazard, potential fire sources, exposures, etc.  Have the plans stamped and signed by an engineer, if they are not already.  If you have a stamped set and are verifying location, ask them to provide manufacturers instructions or documentation per Annex B to substantiate the design.


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