6 foot rule on Smoke detectors

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Mr 3phase

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I am a retired professional fire fighter from New Hampshire, now living in Mass. I am also a licensed electrician. Thus, this question may sound stupid, but I can't find the written rule that states that a hardwired smoke detector installed in a residential dwelling must be within 6' on the bedroom door when located in a hallway. Anyone know where I can find this? It's not in the electrical code book nor the fire alarm book.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I am a retired professional fire fighter from New Hampshire, now living in Mass. I am also a licensed electrician. Thus, this question may sound stupid, but I can't find the written rule that states that a hardwired smoke detector installed in a residential dwelling must be within 6' on the bedroom door when located in a hallway. Anyone know where I can find this? It's not in the electrical code book nor the fire alarm book.

That's because there is no such rule unless it is a local amendment. The rule is in the instruction for the smoke detectors. I believe they can cover an area of 30 feet-.
 

Mr 3phase

Member
I know of no local ammendment. I installed commerical fire alarm systems for several years, and know many of the rules and regs very well, but I could not find this one and Boston Fire claims it exists.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I know of no local ammendment. I installed commerical fire alarm systems for several years, and know many of the rules and regs very well, but I could not find this one and Boston Fire claims it exists.

Here is what the instruction for Firex sd states


Typical Single Story Home
Install a smoke-alarm on the ceiling or wall inside each bedroom and in the hallway outside each separate sleeping area. If a bedroom area hallway is more than 30 feet long, install a smoke alarm at each end.
If there is a basement:
Install a smoke alarm on the basement ceiling at the bottom of the stairwell.
Typical Two-Story or Split Level Home
? Install a smoke alarm on the ceiling or wall inside each bedroom and in the hallway outside each separate sleeping area. If a bedroom area hallway is more than 30 feet long, install a smoke alarm at each end.
? Install a smoke alarm at the top of a first-to-second floor stairwell.
If there is a basement:
? Install a smoke alarm on the basement ceiling at the bottom
 

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
That's because locations of smoke alarms aren't in the NEC...

We get the locations from the Building Code.
Same here. Some localities in Minnesota have local smoke / CO detector rules, but the bulk of the State is regulated by the Minnesota State Building Code.
 

dhalleron

Senior Member
Location
Louisville, KY
Unless it is a local requirement then the 6' rule does not exist to my knowledge.

NFPA 72 2010 29.5.1.1 Required Detection.
(2)*Outside of each separate dwelling unit sleeping area, within 21 ft (6.4 m) of any door to a sleeping room, with the distance measured along a path of travel.

Most smoke detectors or smoke alarms do not have a listed spacing. A few will list spacing in the installation instructions, but most wil not. The national fire alarm code allows you to use heat detector spacing instead. That is where most people get the 30' spacing rule.

The 21' rule came from here:
NFPA 72 2010 17.6.3.1.1* Spacing.
(2) All points on the ceiling shall have a detector within a distance equal to or less than 0.7 times the listed spacing

30' x 0.7 = 21'
 
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