# smokes, AGAIN.



## rktect 1 (Nov 28, 2011)

OK. 2006 IRC section313.1 states that a household fire alarm system in accordance with NFPA 72 shall be permitted.  It is to provide the same level of smoke detection and alarm as required by this section for smoke alarms.

So, is a household fire alarm system in accordance with NFPA 72 different than say an ADT, or equal, household security system which COULD include smoke detection and alarm?  Does section 313.1 NOT require adherence to section 313.3 for power source to each and every unit via a direct hard wired connection such as low voltage wiring?


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## chris kennedy (Nov 28, 2011)

I'm not understanding the question. Are you saying an ADT system has battery only powered devices that communicate via RF or such?


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## rktect 1 (Nov 28, 2011)

chris kennedy said:
			
		

> I'm not understanding the question. Are you saying an ADT system has battery only powered devices that communicate via RF or such?


I am not certain I understand the difference, if any, between what is a home security system and a "household fire alarm system"

Is the ADT, or equal, security system in accordance with NFPA 72 smoke detectors or not?


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## fireguy (Nov 28, 2011)

rktect 1 said:
			
		

> OK. 2006 IRC section313.1 states that a household fire alarm system in accordance with NFPA 72 shall be permitted.  It is to provide the same level of smoke detection and alarm as required by this section for smoke alarms.So, is a household fire alarm system in accordance with NFPA 72 different than say an ADT, or equal, household security system which COULD include smoke detection and alarm?  Does section 313.1 NOT require adherence to section 313.3 for power source to each and every unit via a direct hard wired connection such as low voltage wiring?


Definitions:

A smoke alarm is a stand-alone unit that does not report to a panel. They are available in 9V, 110V w/battery back-up. One or more smoke alarms can be wired together and may or may not be wired so all smoke alarms make noise when one smoke alarm detects smoke.

A smoke detector reports to a panel.  The panel may or may not trip strobe horns, call a phone or shut off fuel.  There are also combo panels that combine a fire function and burgular function.

A fire alarm system can communicate by wire or by wireless.  Most fire alarm systems are powered by 110V with 12V or 24V battery back-up

At least the above is what my alarm tech tells me and what I remember from what he told me.  I am not allowed to play with wires, I might poke myself in the eye.


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## Builder Bob (Nov 29, 2011)

The main issue is to ensure that if monitoring is switched off, that the alarm system will still function and sound the alarms simitaniously in all rooms with Smokes......

When more than one smoke alarm is required to be installed

within an individual dwelling unit the alarm devices shall be

interconnected in such a manner that the actuation of one alarm

will activate all of the alarms in the individual unit.


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## ICE (Nov 29, 2011)

rktect 1 said:
			
		

> OK. 2006 IRC section313.1 states that a household fire alarm system in accordance with NFPA 72 shall be permitted.  It is to provide the same level of smoke detection and alarm as required by this section for smoke alarms.So, is a household fire alarm system in accordance with NFPA 72 different than say an ADT, or equal, household security system which COULD include smoke detection and alarm?  Does section 313.1 NOT require adherence to section 313.3 for power source to each and every unit via a direct hard wired connection such as low voltage wiring?


I don't have an '06 IRC but the '09 says this:

R314.4 Power source. "Smoke alarms shall receive their primary power from the *building wiring* provided that such wiring is served from a commercial source and shall be equipped with a battery backup."

That eliminates low voltage power [12-24 volt] if one takes the position that "building wiring" is 120/240 volt.  I think that it is reasonable to do so.  Then again, it may depend on your definition of low voltage.


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## rktect 1 (Nov 29, 2011)

ICE said:
			
		

> I don't have an '06 IRC but the '09 says this:R314.4 Power source. "Smoke alarms shall receive their primary power from the *building wiring* provided that such wiring is served from a commercial source and shall be equipped with a battery backup."
> 
> That eliminates low voltage power [12-24 volt] if one takes the position that "building wiring" is 120/240 volt.  I think that it is reasonable to do so.  Then again, it may depend on your definition of low voltage.


Which is exactly how we have been having these installed.  But the last line of section 313.1 states "It is to provide the same level of smoke detection and alarm as required by this section for smoke alarms."  I think at this point, if someone wants to install per NFPA 72, you can not just run over to section 313.3 (313.4 in 2009 IRC).  I have a copy of NFPA 72 and am trying to decifer it in regards to power supply requirements.  But I am neither a fire inspector nor electrician so this portion of this code is a bit tricky for me.  Does NFPA 72 section 29.6 allow a "household fire alarm system" to be hardwired to the fire panel with a rechargable battery backup and from there go low voltage to each individual smoke detector unit in the house?


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## cda (Nov 29, 2011)

rktect

what edtion of 72 are you looking at?

 I do not think an adt type system would meet 72

the couple home fire alarm systems I have seen are basicly full blown fire alarm systems

house power, with battery back up

the last one I saw had to have the detectors changed out because they had only one horn for the entire house. they changed the detector out so that each detector had a sounding unit built in, and would hit the required db level in the sleeping rooms.

29.7.5.7 nfpa 72 2010 edition spells out the standards the contol equipement must meet

now a question I have heard, is does the ahj require monitoring of the system???


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## gbhammer (Nov 29, 2011)

We made a bit of an amendment to avoid confusion.

Subsection R314.4 Power Source is amended by deleting “primary” and substituting “120V/AC”.

Add Subsection R315.4 Carbon monoxide alarms power source. Shall receive their power from 120v/ac and interconnected with smoke alarms with battery backup.


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## Paul Sweet (Nov 30, 2011)

The smoke detectors are still fed from the building wiring as long as the central control panel is fed from the building wiring, and low-voltage wiring is run from there to the individual detectors.  The central panel is required to have battery backup on commercial systems, and also has means of monitoring the wiring to the individual smoke detectors.

Smoke detectors don't work on 120 volts AC, it is dropped in voltage and rectified inside the smoke detector to feed low-voltage DC to the electronics.  Why should it make a difference whether the voltage is dropped inside the smoke detector housing or before it reaches the smoke detector?


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## FM William Burns (Nov 30, 2011)

NFPA 72, 2007 [11.6] and the 2010 edition section [29.6] is pretty clear on the power supplies.


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