hard wired smoke detectors

[GWElect]

I understand that hard wired smokies are limeted to 12 on a circuit ( UL and NFPA 72 .) I need 15. It is residential assisted living. Do they all have to be interconnected? or can I run 2 cuircuits that dont set each other off? My understanding is I cant go low voltage becouse it is a residence. Any ideas?

 

[goldstar]

As far as I know, once you go over 12, 120v interconnected smoke alarms you have to go to a LV smoke detection system. Double check with your AHJ. You'll probably have to get approval before you install.

 

[RICK NAPIER]

The restriction on low voltage alarm systems was in the 2006 IRC and was changed in the 2009 IRC allowing them again. They require monitoring and the panel must be the property of the home owner not a lease program that ADT and other companies use to do.

 

[Dennis Alwon]

I would call the smoke alarm company and see if they have an answer to this problem. I bet they do.

 

[Steviechia2]

I know with Kidde you are able to connect 24 units with 18 of them initiating

 

[GWElect]

I thought that NFPA 72 limits the # to 12. You'r saying the manufacture ( kidde ) can allow more????

 

[RICK NAPIER]

Is this a group home setting? If not the individual units could use hard wired smoke detectors that should not be interconnected beyond each unit and the detectors in the common areas would need to be a low voltage alarm system.

 

[masterinbama]

Kidde model # Model i12060 allows 24 with 18 initiating.

 

[RICK NAPIER]

2007 NFPA 72 article 11.8.2.2(2) In no case shall more than 18 initiating devices be interconnected (of which 12 can be smoke alarms) where interconnected means is not supervised.

So you can have 18 but only 12 smoke alarms.

 

[gadfly56]

2007 NFPA 72 article 11.8.2.2(2) In no case shall more than 18 initiating devices be interconnected (of which 12 can be smoke alarms) where interconnected means is not supervised.

So you can have 18 but only 12 smoke alarms.

Kidde allows 6 other non-alarm devices. So you could have 12 smoke alarms, 6 heat alarms, and 6 relays.

 

[Steviechia2]

2007 NFPA 72 article 11.8.2.2(2) In no case shall more than 18 initiating devices be interconnected (of which 12 can be smoke alarms) where interconnected means is not supervised.

So you can have 18 but only 12 smoke alarms.

Would anybody know the reasoning behind this 12 smoke limit when the manufacturer made it for 18 ?

 

[gadfly56]

Would anybody know the reasoning behind this 12 smoke limit when the manufacturer made it for 18 ?

The glaring weakness of smoke alarms is that they are not supervised. You can pull one out, and the rest don't care. I would guess that the Technical Committee felt this was the best compromise between workable coverage and lack of supervision on the theory of "don't make perfect the enemy of good". I don't have the ambition to hunt down the ROP for this, but knock yourself out if you like.

On reflection, I bet that it wouldn't take more than a dollar or two extra per device to provide supervision. Heck, your smart phone has more power than any high-end fire alarm system, how hard could it be to make your life safety device a little brighter? You could use the interconnect as a polling loop, set one device as master with another as backup and program it all with dip switches. Easy peasy.