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#29364 - 09/15/03 11:55 AM Interconnected Smoke Alarms - Maximum of 12
ThinkGood Offline

Registered: 08/07/02
Posts: 1084
Loc: Milwaukee, WI
(Relative to residential installations...the reason why this came up is that I recently saw literature for "BRK Electronics" smoke alarms that states a maximum of 12 alarms can be interconnected. Further research indicated that the UL imposed this limit.)

Has anyone ever had a situation where more than 12 alarms are needed?

To keep this as simple as possible, let's use an example house without getting into attics, basements, etc.

Bedrooms - 1 alarm per room = 5 alarms
Living Room = 1 alarm
Dining Room = 1 alarm
Den = 1 alarm
Top of staircases = 3 alarms
Hallways = 3 alarms

Again, this is just an example, so there may be locations where an alarm should be, or locations where an alarm should not be due to false alarms.

According to this example, there are 14 alarms.

From what I understand, according to various codes, all new-construction houses must have interconnected alarms.

How does one handle such a situation?

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#29365 - 09/15/03 12:12 PM Re: Interconnected Smoke Alarms - Maximum of 12
HotLine1 Offline


Registered: 04/03/02
Posts: 6792
Loc: Brick, NJ USA
There are alarms made and available that are interconnectable in quantity higher than the 12 for the BRK

Firex is one brand.

I don't dabble in resi, but there are units available


#29366 - 09/15/03 12:28 PM Re: Interconnected Smoke Alarms - Maximum of 12
iwire Offline

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
At that point I am thinking a Fire Alarm Panel with smokes, heats, horn strobes and maybe some pull stations.

But that is just the commercial side of me.

Is that done in large single family dwellings?

Bob Badger
Construction & Maintenance Electrician

#29367 - 09/15/03 01:42 PM Re: Interconnected Smoke Alarms - Maximum of 12
sparky Offline

Registered: 10/18/00
Posts: 5545
Bob, i get beat out of the smokes on most high end residentials due to thier low v interface with everything else

pulls & strobes then become a more viable option with the low-v panel

for the most part, they become part of the burgler alarm setup

guess i should throw these gems into this thread too

#29368 - 09/15/03 02:08 PM Re: Interconnected Smoke Alarms - Maximum of 12
Bjarney Offline

Registered: 04/10/02
Posts: 2561
Loc: West-Southern Inner-Northeast ...
Unless local codes intervene, the simplest thing would be to have two zones. Split as upstairs/downstairs, or day/night occupied. That may also minimize confusion of tracking down where the event occurred. Having some central control/reporting may be response time wasted in a residential setup, and kill any advantage of isolated systems.

Of course, building occupants {er, parents} should be well aware of multiple alarm zones.

[This message has been edited by Bjarney (edited 09-16-2003).]

#29369 - 09/15/03 02:34 PM Re: Interconnected Smoke Alarms - Maximum of 12
LK Offline


Registered: 01/21/03
Posts: 1721
Loc: New Jersey
If you install a control panel with smokes you will still be required to have the interconnect system. We tried to install 24v Fire Panel only, and every time they required the interconnect system also be installed. From what i understand the reason is the owner may discontinue the security service and the fire part would not be kept in working order. We found that most low voltage fire systems are not installed to meet UL requirements, such as smokes not supervised, wrong sounding devices, sloppy wiring and much more. The required interconnect devices at least provide basic protection if they are tested by mfg. instructions.

#29370 - 09/15/03 08:28 PM Re: Interconnected Smoke Alarms - Maximum of 12
Big Jim Offline

Registered: 07/18/03
Posts: 377
Loc: Denver, CO USA
LK, I'm a little confused here. I don't mess with alarms much but I know that, on the couple of monitored systems I've touched, I can go in and cut the phone lines to the monitoring company and not affect the integrety of the local system one whit. All pulls, smokes, and local alarm will still function 100%. Why would they cry about a system that is inherently better in the first place (assuming it was installed and inspected originally)?

#29371 - 09/15/03 11:18 PM Re: Interconnected Smoke Alarms - Maximum of 12
ThinkGood Offline

Registered: 08/07/02
Posts: 1084
Loc: Milwaukee, WI
Thanks for the quick and informative responses!

#29372 - 09/16/03 05:19 AM Re: Interconnected Smoke Alarms - Maximum of 12
ElectricAL Offline

Registered: 10/10/01
Posts: 615
Loc: Minneapolis, MN USA
My experience with smoke detection setups for dwellings, specifically, one & two family, is that there are at least three AHJs having authority per installation.
  • Electrical Inspector for the wiring (if any).
  • Building Inspector for the placement of the detectors per building code.
  • Fire Marshall for the placement of the detectors per fire code.

Since the Fire Marshall and Building Inspector don't share each and every page of the same code one gets different requirements quoted as gospel, depending upon who's talking. I have learned that the first duty of the system is to increase the chance of survival of any occupant present at the time of a fire, and that all else is secondary. Because of the larger amount of time individual occupants spend sleeping, special attention is paid to placing the detectors and their alarms so as to wake the sleeper.

If the system also contacts a remote supervisory service, fine, but that is extra.

Here, the code(s) language(s) that is(are) enforced results in line powered interconnected battery backup smoke detectors with integral alarms being the least cost for new construction. Devices integrated with a central security package can not be substituted for this. I've seen interface relays used for the smokes to communicate with the security system, but, in my experience, supervised system installers don't want to support the interface. So, as a result, I've seen both systems installed side by side.
Al Hildenbrand

#29373 - 09/23/03 03:24 AM Re: Interconnected Smoke Alarms - Maximum of 12
Pinemarten Offline

Registered: 08/23/03
Posts: 122
Loc: Edmonton, AB, Canada
To respond to the original post, we have a similar rule in Canada.
On a residential circuit, the limit is 12 devices or 85% amperage of the overcurrent device, which ever is the 'lesser'.
Even though the draw on a smoke is minimal, the limit is still 12.


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