Smoke detector placement

JoeNorm

Senior Member
I am wondering if smoke detectors are always most effective on the ceiling as opposed to on a wall, assuming both are done within manufacturer specs? I am in the middle of a rough in and was considering placing them on the walls but was wondering if I should always opt for ceiling if possible? Safety and paper functioning being the number 1 concern.
 

hbiss

EC, Westchester, New York NEC: 2014
All things being equal, IMO they look better and more professional on the ceiling and I think people expect to see them there. Whenever I see them on walls they usually are retrofits or battery only smokes installed by the HO or landlord.

If you follow the manufacturer's instructions they should function equally in either location.

-Hal
 

MAC702

Senior Member
If you put them on a high ceiling, please put them NEAR the wall, so we don't have to go to the shop for the 16' A-frame ladder to service it.
 

infinity

Moderator
Staff member
If you think that the smoke will enter the room through a door then just above the door is probably the best location. If the room is on fire then the location won't matter that much. I have 12' ceilings in my bedrooms and the smoke alarms are on the ceiling, I'm actually thinking of moving them to a lower location on the wall.
 

ceb58

Senior Member
If you put them on a high ceiling, please put them NEAR the wall, so we don't have to go to the shop for the 16' A-frame ladder to service it.
You must be careful when placing them near a wall. if they are within 12 inches of the wall they can be in a " pocket " that smoke will roll over and not set the alarm off
 

LarryFine

Master Electrician Electric Contractor Richmond VA
I believe most instructions tell us to keep them away from adjoining surfaces; i.e., not within a foot of the wall when on a ceiling, or a ceiling when on a wall.
 

MAC702

Senior Member
You can be within 3' of the wall and I can reach it from a ladder that is placed against the wall.
 

infinity

Moderator
Staff member
Usually they are not permitted in the dead air space which is in the corner 4" down from where the wall meets the ceiling.

 

jxofaltrds

Senior Member
Note that Rob's picture says alarm not detector.

"Often, individuals use the terms “smoke alarm” and “smoke detector” interchangeably. While a common practice, these terms describe very different systems and should not be used as synonyms. Although smoke alarms and smoke detectors may share a few characteristics, they are used for very different purposes."

From Ohio:
https://www.com.ohio.gov/documents/dico_BBSsmokeAlarmsFireSafety.pdf
 

gadfly56

Senior Member
Usually they are not permitted in the dead air space which is in the corner 4" down from where the wall meets the ceiling.

As of the 2010 edition of NFPA 72, this prohibition no longer exists for either smoke detectors or smoke alarms.
 

MAC702

Senior Member
While the dead air space prohibition might be removed from codes, it could still exist in manufacturer's instructions, couldn't it?
 

gadfly56

Senior Member
While the dead air space prohibition might be removed from codes, it could still exist in manufacturer's instructions, couldn't it?
Only because they haven't finished distributing their users manuals printed when the prohibition was in effect. And it does, in fact show up in Kidde's online manuals for the one product I checked.

Please ignore the "shareddocs" link below. It went sideways and I couldn't remove it.
 
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