# Smoke Detector clearance



## Adam12

How far away from a AC supply does a smoke detrector in a ceiling need to be? I have always thought it was 3', cant remember.


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## redbeard43

yes 3 feet


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## Adam12

redbeard43 said:


> yes 3 feet


You are quick on the draw RB.


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## redbeard43

just came across the post 1 min after you made it...lol


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## RonS

It would be nice to stay 3' away if you think it will effect the operation of the detector, but there is no code requirement. The 3' distance is only found in the annex of NFPA 72.


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## william1978

RonS said:


> but there is no code requirement. The 3' distance is only found in the annex of NFPA 72.


 How about 110.3 (B)


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## Mac Hine

Adam12 said:


> How far away from a AC supply does a smoke detrector in a ceiling need to be? I have always thought it was 3', cant remember.


I say 0' from the supply but 3' from the return air. At least that is what I thought but maybe from both. Never put one next to a supply grill.

Edit: Apparently NFPA 11.8.3.5 states from the supply grill- 36". Also 36" from ceiling fans- alot I didn't know in this section.


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## william1978

Welcome to the forum RonS.


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## RonS

William,
If it's in the instructions, then you are stuck with it ... you are correct.
Many detector instructions that I look at direct the installer to NFPA 72.


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## redbeard43

ive done FA for a while, it is 3 feet min away, trust me..doesnt have anything to do with returns.. duct detectors are placed in the returns on larger units, sometimes even the supply. its FA code


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