more than twelve 120V smokes is bad?

[kgingerich]

I'm building a new house and almost ready to drywall. Local codes require 120V smokes w/battery backup interconnected so that when one alarms they all alarm. Right now we're up to 17 smoke alarm locations and after reading the manual for the smokes it says I can only have a maximum of 12 smokes interconnected if they are non supervised. I called the manufacturer and they said it's US code and that's the way it is.

Apparently this is a NAFP code across the US. I called our local fire marshall and he said as long as all 17 smokes are 120V w/battery backup and go off when one goes off he doesn't care what the code says. This just doesn't seem right to me. I'd assume the codes are there for a reason but the fire marshall doesn't seem to care???

Do any of you have more than twelve 120V smokes wired together? I guess I'm just worried that they may not work reliably since it's not wired to code.

We're going to hook them all up this weekend prior to drywall to test them. If they dont' work i'd guess i'm not sure what i'm going to do.

If anyone has any experience in this area i'd appreciate some words of wisdom.

Kyle

 

[Digger]

I'm building a new house and almost ready to drywall. Local codes require 120V smokes w/battery backup interconnected so that when one alarms they all alarm. Right now we're up to 17 smoke alarm locations and after reading the manual for the smokes it says I can only have a maximum of 12 smokes interconnected if they are non supervised. I called the manufacturer and they said it's US code and that's the way it is.

Apparently this is a NAFP code across the US. I called our local fire marshall and he said as long as all 17 smokes are 120V w/battery backup and go off when one goes off he doesn't care what the code says. This just doesn't seem right to me. I'd assume the codes are there for a reason but the fire marshall doesn't seem to care???

Do any of you have more than twelve 120V smokes wired together? I guess I'm just worried that they may not work reliably since it's not wired to code.

We're going to hook them all up this weekend prior to drywall to test them. If they dont' work i'd guess i'm not sure what i'm going to do.

If anyone has any experience in this area i'd appreciate some words of wisdom.

Kyle

My experience is AHJ's (Authorities Having Jusrisdiction such as your Fire Marshall) are one level below god. They can interpret the code any way they want. In this case he is interepting it in your favor. I see his point that as long as they all trip when one does it fullfills what he is most concerned about.

I am at home and dont have a copy of the NFPA or the International Residency Fire code handy to copy and paste the requirements to you. Actually I think my subscription to the International code expred. Maybe someone elses had it.

 

[ano]

I'm building a new house and almost ready to drywall. Local codes require 120V smokes w/battery backup interconnected so that when one alarms they all alarm. Right now we're up to 17 smoke alarm locations and after reading the manual for the smokes it says I can only have a maximum of 12 smokes interconnected if they are non supervised. I called the manufacturer and they said it's US code and that's the way it is.

Apparently this is a NAFP code across the US. I called our local fire marshall and he said as long as all 17 smokes are 120V w/battery backup and go off when one goes off he doesn't care what the code says. This just doesn't seem right to me. I'd assume the codes are there for a reason but the fire marshall doesn't seem to care???

Do any of you have more than twelve 120V smokes wired together? I guess I'm just worried that they may not work reliably since it's not wired to code.

We're going to hook them all up this weekend prior to drywall to test them. If they dont' work i'd guess i'm not sure what i'm going to do.

If anyone has any experience in this area i'd appreciate some words of wisdom.

Kyle

Certainly you can do as you please, but a home big enough to have 17 smoke alarms certainly also should have a 12V alarm panel. If it was me, I'd only install a minimum of 120V smokes to meet the code, then spend your money installing all the 12V smokes you need on the panel. If you can meet the code with 12 120V smokes, than everyone is happy. You do need the 120V smokes, even if you add the others.

 

[kgingerich]

Thanks for the replies. I've read the code myself and it is clear that you can only have a maximum of 12 smoke detecting devices interconnected in a non supervised state. I believe we are clearly in violation of the code. However, I too see the fire marshalls point that if it works and my family gets out of the house safely who really cares what the code says. On the flip side, when it comes time to sell the home, will the inspector count them up and tell me to rewire the whole place.

The true question here is: why is there a 12 smoke limit? If it's because reliability of the system decreases after 12 then I'd be concerned. If it's only because some guy likes the number 12 then who cares.

I still plan on installing a relay in one of the smokes and wiring it back to my M1G.

Kyle

 

[RobWalker]

The true question here is: why is there a 12 smoke limit? If it's because reliability of the system decreases after 12 then I'd be concerned. If it's only because some guy likes the number 12 then who cares.

I know electrical code (Canada) here only allows 12 devices per circuit (and interconnected smokes are all on the same circuit by definition). Could the codes be conflicting? In fact, since you are supposed to have something else on the circuit so you notice if the breaker trips that would limit it to 11 smokes to stay within (electrical) code.

 

[CORT]

Thanks for the replies. I've read the code myself and it is clear that you can only have a maximum of 12 smoke detecting devices interconnected in a non supervised state. I believe we are clearly in violation of the code. However, I too see the fire marshalls point that if it works and my family gets out of the house safely who really cares what the code says. On the flip side, when it comes time to sell the home, will the inspector count them up and tell me to rewire the whole place.

The true question here is: why is there a 12 smoke limit? If it's because reliability of the system decreases after 12 then I'd be concerned. If it's only because some guy likes the number 12 then who cares.

I still plan on installing a relay in one of the smokes and wiring it back to my M1G.

Kyle

It would be nice if someone with authority could explain why there is a limit of 12 smoke detectors on the bus. It seems stupid to me. Of note, Kidde and many other companies allow for 12 smoke detectors and 6 other devices, i.e carbon monoxide detectors, relays, etc.--a total of 18 devices--all on the chain. I don't think the 12 device limit is of electrical limitations. It is probably some arbitrary number that looked good to the people deciding the code that day.

 

[Sandpiper]

Here is what the Fire Alarm Code (NFPA 72) Handbook says about it. [I have snipped parts irrelevant to the issue] In the following excerpt, "supervised" means monitored for integrity, i.e. "trouble alarm".

11.8.2 Interconnection of Detectors or Multiple-Station Alarms.
11.8.2.1........
11.8.2.2 The interconnection of smoke or heat alarms shall comply with the following:
(1) Smoke or heat alarms shall not be interconnected in numbers that exceed the manufacturer’s
recommendations.
(2) In no case shall more than 18 initiating devices be interconnected (of which 12 can be
smoke alarms) where the interconnecting means is not supervised.
(3) ............

The intent of the requirements in paragraph 11.8.2.2 is to recognize that systems designed
for use in large residences differ from those intended for use in smaller residences. It is
important to remember that the configuration allowed in paragraph 11.8.2.2(2) incorporates
heat alarms that may be connected to multiple-station smoke alarms. The number of multiplestation
smoke alarms used to protect a residence is limited to 12 because the wiring that
interconnects the alarms is not monitored for integrity. For applications that require more
than 12 smoke alarms, a fire alarm system with a control panel must be used.
For large residences that require many alarms and the interconnection of different types
of alarms or sensors (such as carbon monoxide or water flow switches on a sprinkler system)
the use of a household fire alarm system should be considered. If multiple-station smoke
alarms are to be interconnected with other types of alarms, the equipment must be listed as
compatible. Manufacturer’s instructions provide guidance on the compatibility of equipment.

 

[hockeypuck]

Maybe they figure if you home needs more than 12 units you should have a monitored low voltage fire security system. I have no idea why they limit it to 12. You could buy a relay and put the 18 on two seperate circuits. Code also says it is wrong to install any product against manufactures recommendations. So it appears you have a double whammy. But as said before, bow to your local authority. He is god.

 

[CollinR]

I would check and see if they guy will accept system grade UL residential/commercial smokes, I prewire many many new constructions no troubles in Tulsa.


I'm not going to be hooking up relays to existing smokes, they can have 2 seperate systems, all system grade smokes or no monitored smokes all. Not to mention electricians seem to do a piss poor job of locating smokes. I see them near returns, near kitchens and bathrooms... Doesn't really make much difference if the code enforcer doesn't know how these things work in reality.

 

[nightwalker]

I've done many installations here in pennsylvania using either an HAI or DSC panels. So far no inspector has given me any trouble with the low voltage panel being the only smoke detectors in the house. I've also had many that that had more than 12, with the requirements that they also be in bedrooms as well as hallways depending on their length. The most i've had to do is show up and blow smoke in the smoke detector for a couple of inspectors so they could see that the system did go off and sound the alarms and that the sounders were of the proper db levels.

 

[kgingerich]

I called Kidde hoping someone would say "the code is stupid, you can install all the smoke detectors you'd like". As expected the lady on the phone said she could not confirm that it would work properly if I used 18 on one circuit because code says 12. However, she did say that it "should work". I think it's obvious that it's going to work fine, and the fact that none of the fire marshalls I called seem to care about the code means it's a BS code. So I'm going to install all 18 interconnected smokes and put a relay on the one closest to my M1G.

-Kyle

 

[BraveSirRobbin]

I have not read through this entire thread so excuse me if this has already been suggested, but why not just use two smoke detector runs? You can just use two relays (one for each run) or (what I would do) is maybe substitute a GE smoke detector (more info HERE) in place of one of the Kiddies (one for each run) which already has the relay inside of it.

I do admit though that smoke detectors are not my strong point...

 

[Digger]

I have not read through this entire thread so excuse me if this has already been suggested, but why not just use two smoke detector runs? You can just use two relays (one for each run) or (what I would do) is maybe substitute a GE smoke detector (more info HERE) in place of one of the Kiddies (one for each run) which already has the relay inside of it.

I do admit though that smoke detectors are not my strong point...

Most likely the AHJ would not like that. If he trips one detector he wants them all to sound. With two detector runs that will not happen.

Thinking about why there may be a limit. Since one detector trips all on the circuit and it has to have a battery backup maybe the battery in the detector that trips would not have enough capacity to trip more than 12 others into alarm????? Just a thought.

 

[BraveSirRobbin]

I have not read through this entire thread so excuse me if this has already been suggested, but why not just use two smoke detector runs? You can just use two relays (one for each run) or (what I would do) is maybe substitute a GE smoke detector (more info HERE) in place of one of the Kiddies (one for each run) which already has the relay inside of it.

I do admit though that smoke detectors are not my strong point...

Most likely the AHJ would not like that. If he trips one detector he wants them all to sound. With two detector runs that will not happen.

Ah, yea, I knew it would be something obvious that I overlooked!

 

[CollinR]

I think the number 12 has more to do with it being a 120v circuit then anything else, IIRC you can't have more then 12 devices. That can be 6 dual recepticles or 3 quad recepticles or many numbers of other combinations but I think all outputs on a single circuit must be less then 12.


Why not just use system grade stuff? You should be able to point out that system grade stuff is obviously there to kick in past 12. Use the catch phrase "supervised" system as thats what you would actually have. Good enough for hospitals with hundreds of sleeping areas it's good enough for a single dwelling.