smoke detectors location

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mtnelectrical

Senior Member
Location
Essex, New Jersey
A GC a just started working for told me to not put my sd near the a/c ducts
(not the grill), because fire inspector said to keep a distance from it. Have your ever heard that before? They run the ducts below the ceiling so they have to box and sheet rock the ducts and my box for the sd are 12" away.
 
Cavie

Cavie

Senior Member
Location
SW Florida
mtnelectrical said:
A GC a just started working for told me to not put my sd near the a/c ducts
(not the grill), because fire inspector said to keep a distance from it. Have your ever heard that before? They run the ducts below the ceiling so they have to box and sheet rock the ducts and my box for the sd are 12" away.
Click to expand...

In these parts, SD must be 3' from any vent and bathroom doors. fire marshall rules
 
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MJW

Senior Member
He may have been concerned about the dead air space in the corner where the ceiling meets the framing for the ductwork. I think the dead air space only extends 4" in each direction. Or more likely he got ducts and grills confused.
 
iwire

iwire

Moderator
Staff member
Location
Massachusetts
Guys I think we need to forget the distance from the grill requirement for a moment

mtnelectrical said:
A GC a just started working for told me to not put my sd near the a/c ducts
(not the grill), because fire inspector said to keep a distance from it. Have your ever heard that before? They run the ducts below the ceiling so they have to box and sheet rock the ducts and my box for the sd are 12" away.
Click to expand...

If I recall you can not place a smoke detector in the 'dead zone' near the intersection of a vertical and horizontal surface.

sd_placement.gif


The measurements in that image are less then I recall but maybe someone with NFPA 72 can jump in.
 
RJohnsonMasterElectrician

RJohnsonMasterElectrician

Senior Member
Location
Right now ??, previously VT
Cavie said:
In these parts, SD must be 3' from any vent and bathroom doors. fire marshall rules
Click to expand...

and entry into kitchens (unless that was a state code) for me.

3' is minimum, if its a high flow unit you have to be farther than the 3' mentioned. High flow (off the top of my head without code book is 8 to 10 air exchanges an hr instead of the normal 4 to 6 or 6 to 8.

Ok any where on the ceiling is ok as long as its 4" away from a corner of a wall and you at the highest point if its a cathedral.

If you install the smoke on the wall you must be at least 4" from the ceiling and no more than 12" from the ceiling.
 
Pierre C Belarge

Pierre C Belarge

Senior Member
Location
Westchester County, New York
ron said:
NFPA 72 says to keep them far enough away so that they (detectors) work.
It is only in the non-enforceable annex where they say 3' from a register.
Click to expand...



NFPA 72 is a starting point for most jurisdictions. One must also pay attention to the local jurisdictional requirements. Such as in NYS. There is the NYS Fire Code, which is long and has many jurisdictional (state wide) references.
 
A

A-F-E

Member
Now lets not over look the manufactures requirements IE the directions. Which we are required to comply with per NEC and NFPA 72. And I have been on jobs were you have that he said she said from inspectors,helpers,fire marshals and the only thing I did was give them the directions and say if you want me to do what ever with the smokes it violates the installation. Nicely of course.
 
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