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Joined: Dec 2006
Posts: 21
P
Member
Hey
Can anyone direct me to a section in the NEC or NFPA that requires a seperation of Paddle fans from Smoke Detectors on a ceiling. I personnally followed 3 feet as a rule, because that is what has been required of me in the past. Any help defining or finding my rationalle in the code is appreciated.

Thanks

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Joined: Jan 2005
Posts: 5,316
Cat Servant
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I am not aware of anything specific to ceiling fans. At the time smoke detectors were introduces, ceiling fans were nowhere near as popular as they are today .... and the idea of one in the bedroom was unheard of!

Fire testing did clearly demonstrate that most rooms have a "bubble" of stale air where the ceiling meets the wall; that is why we are cautioned not to place detectors within a foot of that juncture.

Would a ceiling fan have a similar effect? I can't say that I know ... but I would not be surprised to find such a 'bubble' very close to the center. Indeed, locating the detector near the mid-point of the blades might actually improve the response ... marginally.

A lot of effort is spent placing the detectors dead center in a ceiling. IMO, this is not justified by fire behavior. That smoke plume seems to spread almost instantly across the entire ceiling. Placing the detector a few feet off center, or even two feet from the wall, seems to have little effect in detector response.

What DOES make a BIG difference is the duct that brings in fresh air. A detector in that path will never detect a fire in the room.

Joined: Jan 2004
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Check out the rather detailed directions in the NFPA 72 Handbook for 2002. New Chapter 11 Section 11.8.3.5.
Covers probably all standard clearances you might need.

Last edited by George Little; 04/04/07 11:32 AM.

George Little
Joined: Jul 2002
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Also you might check the manual that comes with the detectors. Haven't looked at one lately, but I seem to remember some info about fans proximity in the manuals

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I can say from experience (my wife's) you will get warranty calls if they are in the tray with a fan. They pack up with dust and chirp.


Greg Fretwell
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Joined: Mar 2005
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i am not sure about ceilng fans but 3 feet from cold air return is a ibc and ubc rule
also heard 2 foot change in roofline in the same room will be changed(i.e. a bedroom with a dormer that has a vault will not require 2 smokes in that room) also avoid placing smoke within 12 inches of peak and not exceeding 3 foot from peak

Last edited by watersparkfalls; 04/04/07 10:18 PM.
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I really think there should be some compromises on location for accessibility. A smoke detector that the homeowner can't reach will not get fresh batteries or regular cleaning. The first time they have to pay $50-$100 for someone to go 27' up into the great room ceiling to stop a chirping smoke, it will end up in the trash.


Greg Fretwell
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Greg- That only happens when the battery goes dead and then unit starts chriping on a Sunday morning and won't quit till they hire someone to come out on OT and a preimum pay rate. That's what I've been saying for years. That's a strong argument for a household fire alarm system that has a battery in the FACP and not that 9v. one that is in the smoke alarms. I know the smoke detectors associated with an alarm system could need service eventually but nothing like a smoke alarm that typically gets installed. I guess I'd not be in favor of a compromise but there are better ways of doing things, a beam detector could also be used, cost not being an issue.


George Little
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Since we are going to interconnected, hard wired alarms, one thing that could be done is to eliminate the unit battery and have a central battery backup but that could reduce the redundency and create a situation where it only takes two failures to disable all the alarms. This may be getting better with the extended life batteries that may last the useful life of the alarm, assuming you don't have kids cooking who use the alarm as a "dinner's done" indication.
I still think these should be installed in an accessible location if they will give a reasonable level of protection. Engineering the last .00% percent of theoretical effectiveness at the cost of maintainability is short sighted.
Putting one in a tray with a fan is just stupid. Most trays aren't really big enough to get all the clerarances anyway.


Greg Fretwell

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