Interconnected Smoke/CO detectors exceeding limits
In our ongoing remodel of a brownstone, I count 15 Smoke/CO detectors in the architect’s drawings. The remodel is for a single family home and, as far as I understand from laws and code, all 15 detectors must be interconnected in order to sound an alarm at the same time.
For traditional wired Smoke/CO detectors (Kidde, First Alert), regulation (NFPA 72) sets a limit of 12 interconnected units (additional units can be interconnected, but may not be Smoke/CO). Apparently, this limit doesn’t apply to wirelessly interconnected alarms, such as the Nest Protect. Amazingly though, Nest Protect is limited technically to 18 per account.
I’m sure that Nest Protect is a nice product, but honestly, I just don’t want all the bells and whistles on it. I don’t need it to light up every time I walk beneath it. I don’t want it to speak to me. And I don’t care to configure these detectors on an app.
Ideally, I would like a hardwired solution (power and interconnect). What designs, solutions, and products have others on this forum encountered? Is my interpretation of interconnection req uirements incorrect after all? Could I create two separate interconnection circuits? Is a fully managed fire alarm system (e.g. Honeywell) my only alternative beyond Nest Protect?
Thank you.
lozadorealty
in General Discussion 4 years and 10 months ago
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10 replies
jimhillra | 4 years and 10 months ago
Cosmo Jetz: A hallway detector does NOT cover the bedroom. You need both.
jimhillra | 4 years and 10 months ago
R-2 means residences with three or more families. R-3 means 1 and 2 family buildings. I is institutional use.
jimhillra | 4 years and 10 months ago
NYC Building Code Chapter 9:
907.2.11.1 Smoke alarms in Groups R-2, R-3, and I-1. Single-or multiple-station smoke alarms shall be installed and maintained in Groups R-2, R-3, and I-1, regardless of occupant load at all of the following locations within all dwelling units:
1.On the ceiling or wall outside of each room used for sleeping purposes within 15 feet (4572 mm) from the door to such room.
2.In each room used for sleeping purposes. Exception: Single-or multiple-station smoke alarms in Group I-1 shall not be required where smoke detectors are provided in the sleeping rooms as part of an automatic smoke detection system.
3.In each story within a dwelling unit, including below-grade stories and penthouses of any area, but not including crawl spaces and uninhabitable attics. In dwellings or dwelling units with split levels and without an intervening door between the adjacent levels, a smoke alarm installed on the upper level shall suffice for the adjacent lower level provided that the lower level is less than one full story below the upper level.
Guest User | 4 years and 10 months ago
i believe that the npfa72 rule is in place for degradation of current…by using the interlock relay on a second circuit you avoid the problem
lozadorealty | 4 years and 10 months ago
jimhillra: Could you provide a reference for that design? I wasn’t aware that a hallway detector covers a bedroom if within a certain distance.
Eman137: I’ve come across that idea on a forum (mikeholt.com). I’d love to know whether this still satisfies the NFPA 72 rule (limit of 12). I don’t even know whether the limit of 12 is technical in nature to begin with.
Guest User | 4 years and 10 months ago
you probably would set the 11th detector to activate an interlock relay, which would activate the remaining detectors…
https://www.grainger.com/product/3AU39?gclid=EAIaIQobChMIubCzwvag7AIVIodbCh0auw3gEAQYAiABEgIzDvD_BwE&cm_mmc=PPC:+Google+PLA&ef_id=EAIaIQobChMIubCzwvag7AIVIodbCh0auw3gEAQYAiABEgIzDvD_BwE:G:s&s_kwcid=AL!2966!3!281698276011!!!g!471328313888!&gucid=N:N:PS:Paid:GGL:CSM-2295:4P7A1P:20501231
jimhillra | 4 years and 10 months ago
15 does seem a bit excessive for a single-family. The code states that you need one in each bedroom and outside each bedroom within 15 feet of the bedroom door. We usually manage to get one in the hall to cover most, if not all of the bedrooms on that floor. In addition to those, you need one per floor, which can be the one in the hall outside the bedrooms. For the floor with the kitchen, strongly consider installing it as far away from the kitchen as possible, on the other side of a header or doorway if possible. It’s a huge pain when the cooking sets off every single detector in the house. I can’t imagine the noise of all 15!
lozadorealty | 4 years and 10 months ago
I appreciate your comments.
You’re right; it’s not a new construction; however, the work falls into permitted work substantial enough to easily provide the type of access to install a hardwired system. From a rule/code perspective it looks like a new system is in order. I should also mention that I don’t mind having the work done – all walls and ceilings are stripped and spaces are easily accessible.
And correct, the architect took all of this into consideration and placed detectors in each bedroom and hallways. We haven’t had electrical work done yet, so there’s certainly a question for them. But in my experience, it is necessary to do thy homework first.
I’d love to hear how others have solved the 12+ interconnected detector design problem.
cate | 4 years and 10 months ago
I could be wrong, but don’t the electricians automatically put in whatever is required by code for smoke detectors, especially if you don’t have a fancy lighting or electrical plan from an architect? Though it sounds like you do have one of those. (We have three smoke alarm alarms in a three story house — code from 10 years ago. Since then code now requires them in bedrooms, I believe, in addition to halls.)
GreenThinker | 4 years and 10 months ago
Inspectors aren’t that thorough. This might be of help, since it’s not a newly constructed building and you possibly aren’t opening up all the walls, perhaps you can leave 3+ interconnected from the rest.