# Residential hard wired smoke detectors



## jacks14 (Nov 17, 2010)

Quick question...can you add a new smoke detector by just tapping off existing system or do you have to locate the last smoke detector and continue the daisy chain from there?


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## B4T (Feb 10, 2009)

jacks14 said:


> Quick question...can you add a new smoke detector by just tapping off existing system or do you have to locate the last smoke detector and continue the daisy chain from there?


You can tap into anywhere on that type of system.. BUT you need to have all the same brand and model

Only time you need to find the last smoke detector is when you have a Fire Alarm panel that uses a EOL resistor..


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## TOOL_5150 (Aug 27, 2007)

B4T said:


> You can tap into anywhere on that type of system.. BUT you need to have all the same brand and model
> 
> Only time you need to find the last smoke detector is when you have a Fire Alarm panel that uses a EOL resistor..


Just to expand a little more on what B4T said.. you need to use 14/3 or 12/3.. whatever is installed, so you get the communication path as well, and it can be attached anywhere in the circuit. But, Im sure you know that anyway.


~Matt


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## Jcode (Mar 24, 2011)

If the inspector likes you I do believe you could get by with Wireless hardwired smokeys. $45-50 a Peace

Saved us a lot of hell on an old apartment building.

4th year working as a apprentice under step dad (Masters and business owner). So not positive about codes with doing this.


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## erics37 (May 7, 2009)

You can T-tap resi smoke detectors all ya want.


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## electricalcj (Feb 9, 2011)

tap anywhere in the system. You are only dealing with voltage and signals.


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## robnj772 (Jan 15, 2008)

erics37 said:


> You can T-tap resi smoke detectors all ya want.


 
That is not true. You are only allowed up to 16 on one circuit.


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## leland (Dec 28, 2007)

*cross referance.*

All manufacturers have a similar list,and specs.

http://www.brkelectronics.com/downloads/cross-referencing-list

Some limit you to the number of devices per ckt.

ex- kidde allows 24 others are 14, so check both specs.


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## nrp3 (Jan 24, 2009)

The kidde ones are limited to 12 smokes, 6 heats or CO, and 6 other types, relays? At least the users manual I looked at. I guess NFPA 72 limits the interconnected line voltage type smoke detector count to 12.


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## leland (Dec 28, 2007)

nrp3 said:


> The kidde ones are limited to 12 smokes, 6 heats or CO, and 6 other types, relays? At least the users manual I looked at. I guess NFPA 72 limits the interconnected line voltage type smoke detector count to 12.




Architectural and Engineering
Specifications
The smoke alarm shall be Kidde model PE120 or approved equal. It shall be
powered by a 120VAC, 60Hz, 80mA source along with a 9V battery back
up. The unit shall incorporate a photoelectric sensor with nominal sensitivity
of 2.06%/ft. The temperature operation range shall be between 40˚F and
100˚F (4˚C and 38˚C) and the humidity operation range shall be 5% - 95%
relative humidity.
The smoke alarm can be installed on any standard single gang electrical
box, up to a 4” octagon junction box. The electrical connection (to the
alarm) shall be made with a plug-in connector. A maximum of 24 Kidde
devices can be interconnected in a multiple station arrangement. The
interconnect system must not exceed the NFPA (National Fire Protection
Association) limit of 18 initiating devices, of which 12 can be smoke alarms.
With 18 initiation devices (smoke, heat, CO, etc.), interconnected, it is still
possible to interconnect 6 strobe lights and or relay modules. The unit shall
provide optional tamper resistance that deters removal of the unit from the
wall or ceiling.
The alarm shall include a test button that will electronically simulate the
presence of smoke and cause the unit to go into alarm. ............

Must admit- I did not know of NFPA limit. But 18 is a lot of devices for a house.

So- no more than 12 smokes, just save room to add a relay device to trigger the 2nd interconnect ckt.

Still,if you need that many devices a 'system' is in order.


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## nrp3 (Jan 24, 2009)

I had my hopes up. Thought you had pointed me to something new. I wonder if those relays will trip on 9v battery backup though. Have a few apartments around here that are still using the line voltage smokes in the common areas.


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## thegoldenboy (Aug 15, 2010)

I remember reading something a few years back from Kidde that the entire circuit conductors couldn't exceed XXXX' from the first smoke detector to the last. I believe I still have one of the manuals at my house, I'll try to cite it later on.


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## nrp3 (Jan 24, 2009)

It said 1000 feet in the users manual I looked at i4618.


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## leland (Dec 28, 2007)

nrp3 said:


> I had my hopes up. Thought you had pointed me to something new. I wonder if those relays will trip on 9v battery backup though. Have a few apartments around here that are still using the line voltage smokes in the common areas.




Yes they will,that is the whole idea of the interconnects with back up.:thumbsup:


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## crosport (Apr 4, 2010)

B4T said:


> You can tap into anywhere on that type of system.. BUT you need to have all the same brand and model
> 
> Only time you need to find the last smoke detector is when you have a Fire Alarm panel that uses a EOL resistor..


 But you can tap off any device as long as you use a 4 conductor cable!


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## B4T (Feb 10, 2009)

crosport said:


> But you can tap off any device as long as you use a 4 conductor cable!


I hope you mean (3) conductor cable plus ground..

Or are you talking about a 24V. Fire Alarm system???


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## crosport (Apr 4, 2010)

B4T said:


> I hope you mean (3) conductor cable plus ground..
> 
> Or are you talking about a 24V. Fire Alarm system???


 Sorry I meant 4 conductor plus a ground in a low voltage system.Tap in anywhere you like.Do it regularly.


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