scottam99
Member
- Location
- Vero Beach Florida
I was informed by an inspector per NFPA72 Tip ofCeiling fan blade must be 3 feet away from smoke detectors. Just thought I'd pass this on, It's the first I ever heard of it....
Smoke detectors and Ceiling fans
- Thread starter scottam99
- Start date
- Status
- Location
- Logan, Utah
That requirement is also part of most single station smoke alarm installation instructions.
Also remember to keep the alarm 3' away from any supply or return grills or bathroom doors.
Chris
A/A Fuel GTX
Senior Member
- Location
- WI & AZ
- Occupation
- Electrician
Chris, what's the logic there? Moisture?
ceknight
Senior Member
Different Chris, but yep, moisture. Steam from the shower can trigger false alarms and/or cause internal corrosion. Or so I'm told...
- Location
- Logan, Utah
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
The 3' rule from fans return grills and vents is because it would keep the smoke from getting to the detector.
I did not know there was a rule from bathrooms but it makes sense. I had a customer who would steam up the bathroom so every time he showered it would set off the alarm. Apparently the steam ionizes the air and sets it off.
I did not know there was a rule from bathrooms but it makes sense. I had a customer who would steam up the bathroom so every time he showered it would set off the alarm. Apparently the steam ionizes the air and sets it off.
Jim W in Tampa
Senior Member
- Location
- Tampa Florida
Mostly it just that any heavy air flow would keep smoke awa. Rule has been inforced here for many years. Can be a real pain sometimes in bedrooms if you are there first and then Mr AC screws it up. All part of why yo need to look at all the pages. One of you will be moving.
Security101
Senior Member
- Location
- Northern Indiana
I would figure you would need even more distance if using one of these http://www.bigassfans.com/ :grin:
Jim
Jim
construct
Senior Member
- Location
- Branson, Missouri
Dennis Alwon;126562 I did not know there was a rule from bathrooms but it makes sense. I had a customer who would steam up the bathroom so every time he showered it would set off the alarm. Apparently the steam ionizes the air and sets it off.[/QUOTE said:Also, with the ionization type dectectors, burnt toast or bacon will set them off. That's why NFPA 72 requires they be installed no closer than 20' to a cooking appliance unless equipped with a silencing feature.
brantmacga
Señor Member
- Location
- Georgia
- Occupation
- Former Child
If I remember correctly, the wording of the code is "forced air supply"; I do not interpret that to include returns also.
A few years ago I was the EC on a resi development where most of the floorplans made it impossible to keep 3' from the hallway return and keep within distance on the required smoke detector outside the bedroom doors. Just pointing out these situations do exist.
If they meant returns also, then it should be specifically noted.
My simple mind concludes that a return will draw smoke towards the smoke detector if it is placed in the vicinity.
skeshesh
Senior Member
- Location
- Los Angeles, Ca
The smoke detector's sensitivity to false alarms depends on the product as well. There are many products on the market that have more than one sensing technology with pratically eliminates false alarms. I had a contractor show me a janitors closet in an installation where he kept the hot water for mopsink, etc. running for a couple of minutes with the smoke detector installed - no alarm. When he opened the door the room was full of steam. I let them keep them in in those closets since there will likely not be a situation like that frequently to damage the alarm. This type of product is also useful for kitchens etc.
The other issue is the moisture which comes into play in shower areas and such. Smoke detectors are generally not rated for operation in a wet area or areas where excessive moisture is present. In such cases use of a heat detecter is appropriate.
The other issue is the moisture which comes into play in shower areas and such. Smoke detectors are generally not rated for operation in a wet area or areas where excessive moisture is present. In such cases use of a heat detecter is appropriate.
ptonsparky
Tom
- Occupation
- EC - retired
We pretty much center ours on the door into the room about 16-18" from the wall. Some small bedrooms with fans just don't leave much room.
Note: Placement really has nothing to do with the NEC unless you consider installation instructions.
Note: Placement really has nothing to do with the NEC unless you consider installation instructions.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
It definitely includes return air grills.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Are you sure it is 20'. I did a house where it would be impossible to be further than 20' from a kitchen and still be near the bedroom area. I rarely install them anymore as they are usually part of the low voltage system.Also, with the ionization type dectectors, burnt toast or bacon will set them off. That's why NFPA 72 requires they be installed no closer than 20' to a cooking appliance unless equipped with a silencing feature.
brantmacga
Señor Member
- Location
- Georgia
- Occupation
- Former Child
explain.
"supply" and "return" are two completely different things.
i am not in agreement with you.
brantmacga
Señor Member
- Location
- Georgia
- Occupation
- Former Child
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Well let me say this-- you won't pass around here...:grin:
brantmacga
Señor Member
- Location
- Georgia
- Occupation
- Former Child
i may come up there and do some work just to have this argument.
i've had one inspector call me out on it; i told him find a dictionary and get back to me. job passed.
anyhow, like i said, if their intent was to include returns, then it should be worded as such.
until then, i won't be convinced otherwise.
i suppose one could say the return is "supplying" a forced air system; i'm not buying it though.
jsharvey
Member
- Location
- Mayetta Ks
It's the air movement.
It's the air movement.
This may be just around here but the Fire Marshall explained it in a class many years ago that the distance was because of the air movement involved with a forced air HVAC unit. To close to the supply and and it blows the smoke away from the detector, to close to the return it can suck the smoke into the unit before setting off the alarm. Either way it would take more smoke build up to activate the detector than if it was away from the vents.
It's the air movement.
i may come up there and do some work just to have this argument.
i've had one inspector call me out on it; i told him find a dictionary and get back to me. job passed.
anyhow, like i said, if their intent was to include returns, then it should be worded as such.
until then, i won't be convinced otherwise.
i suppose one could say the return is "supplying" a forced air system; i'm not buying it though.
This may be just around here but the Fire Marshall explained it in a class many years ago that the distance was because of the air movement involved with a forced air HVAC unit. To close to the supply and and it blows the smoke away from the detector, to close to the return it can suck the smoke into the unit before setting off the alarm. Either way it would take more smoke build up to activate the detector than if it was away from the vents.
construct
Senior Member
- Location
- Branson, Missouri
Sorry for the delay in replying Dennis. I am not always able to visit the forum on a daily basis.
Actually, I was incorrect. NFPA 72 Sec 11.8.3.5 (4): Smoke alarms and smoke detectors installed within a 20 ft horizontal path of a cooking appliance shall be equipped with an alarm-silencing means or be of the photoelectric type.
Also Sec 11.8.3.5 (6): Smoke alarms and smoke detectors shall not be installed within a 36" horizontal path from supply registers of a forced air heating or cooling system and shall be installed outside of the direct airflow from those registers.
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