4 wire smoke over 14/3 ?

[szoostrom]

My current smoke detectors are standard units powered by AC with battery backup.   My wiring is romex 14/2 from the breaker panel to the first detector and 14/3 in series between all other detectors.   I want to replace them with low voltage 4 wire smokes and tie them into my HAI OPII.   I am considering Interlogix 541NCSXT.     Is it possible and safe to use this wiring for 4-wire smokes?   If so, which function goes onto the bare ground wire?   I will of course be using a new wire from the OPII to the first smoke.
 
Is there a forum on this topic already?
 
 

 

[az1324]

Just curious, why do you want to use low voltage? Why not just get a relay output module that works with the 120V detectors?

 

[szoostrom]

Good question az1324.    My standard units are 10 years old and need replacement so now would be the time to switch to LV.  I did consider a relay however I want to use the battery backup built into the OPII / Low voltage system instead of having to put batteries in the standard units every year or two.     Also, it's my understanding from other discussions that there are fewer false alarms with units designed specifically to interface with controllers.

 

[az1324]

You could do 9V Lithiums.  Are false alarms currently an issue?  With LV don't you have to also do a power supervision relay?

 

[Madcodger]

Check local codes on use of battery only units, though, if going that route. Not allowed in some areas. I installed GEs (as I recall) to tie into my Elk wireless and they work well. The house previously had no system prior to our purchase of it. Local code official allowed the wireless and liked them, but noted that if doing a remodel of 20% or more of structure or if wired system had been installed earlier, battery only would not be allowed. Apparently too many instances of them finding detectors with dead batteries (thus no protection). I'm not sure, but believe that is now NFPA code, so likely common.

 

[pete_c]

My preference here was to leave the HV wired smokes and just add LV wired smokes. 
 
Yup; here in the midwest left the contractor installed smokes (120VAC) and put in my own LV smokes and connected them to the panel.  (some ceiling clutter?). 
 
Real wiring PITA though as I zoned the 4-wire LV smokes.  (first floor of the 2 story home was most difficult to wire up).
 
Interesting ....because yesterday my wife (while cooking) triggered one 120VAC smoke in the kitchen but not the nearby LV one.
 
The attached diagram is what I utilized to do my zoned 4 wire LV smokes connection to the OPII panel.

 

[szoostrom]

Thanks for the input and suggestions.    I understand what's been provided.    
 
One further question  - The OPII uses switched power to the LV smokes and resets them when security is armed.    What's the benefit of this vs smokes that are powered separately by 120V AC (with 9V battery backup.)   Is it just the ability to quickly silence the alarms ?
 
No one has mentioned the use of 14/3 on 4 wire smokes, but if anyone has experience with it, please advise.

 

[Del91574]

Romex can be reused for LV and is code compliant, assuming you remove the feed from the HV power source/panel and no branch circuits run through the JB's.
 
 The only item that comes into question is if the AHJ would have an issue with you replacing that portion that was used for a C of O when the house was built as a LV system.yyou
 
While not ideal, you can use all 4 conductors of the 14/3, including ground, but I'd verify there's continuity to EG on the ground conductor. I'd use the bare conductor, install heat shrink or insulate, and use as the negative conductor of the power circuit.
 
In Pete's case, I'd be willing to wager that the HV units are ion and your LV units are photo...the ions always tend to false from cooking smoke while PE's don't, unless there's a lot of smoke.
 
As far as manufacturers of hardware go, be wary of DSC....their hardware requires a switched positive, contrary of other manufacturers, and don't play nice if you mix/match with other manufacturers hardware.

 

[newalarm]

I did what Pete_C did as well. In our case, new rehab, and we did not thing about smokes. Local code also requires one smoke in each sleeping room, and occupiable room i think. So the HV is code compliant.
 
For the LV system, we only placed smokes and thermals in select areas. This is tied to alarm system and monitored. This system is really to alert fire department if no one is home, or if we did not hear siren for some reason.
 
If you ceiling is white, you don't really notice the smokes after a while. they blend right in.

 

[apostolakisl]

I did what Pete_C did as well. In our case, new rehab, and we did not thing about smokes. Local code also requires one smoke in each sleeping room, and occupiable room i think. So the HV is code compliant.
 
For the LV system, we only placed smokes and thermals in select areas. This is tied to alarm system and monitored. This system is really to alert fire department if no one is home, or if we did not hear siren for some reason.
 
If you ceiling is white, you don't really notice the smokes after a while. they blend right in.

 
 
I think you meant "occupiable floor", not room.  I don't think any state has a code requiring a detector in every room.  The code is different for every state.  Most require one inside each bedroom and one on each floor.  Some only require one outside of each bedroom where one detector can count for multiple bedrooms.  Some require both inside each bedroom and outside of each bedroom.  You just have to check.

 

[pete_c]

Way different between FL and IL ~ 13 years ago.  The FL contractor put a smoke in every room plus the hallways of the elevated ranch except for the bathrooms.  I replaced them all at the 10 year mark.   Most difficult ones to replace were the carpeted rooms with high ceilings. 
 
In IL contractor put one on every floor.  I went with a more granular zoned setup connecting it to my panel.  (keeping both sets up)
 
Today (2013) building codes for smoke detectors may be different.  Electrical went from Romex to conduit here in the last 10 years.  It was an extra building cost to utilize conduit here some 13 years ago. 

 

[tmbrown97]

Here they're in every room and outside every room - so I have something like 13 detectors...  
 
and as DEL said, detectors designed to be connected to a monitored system take longer to alert - they're better at detecting smoldering fires - the ones that are just to wake you up are set to respond faster but may false more.

 

[Del91574]

The hard and fast rule across the board for the US is this (hasn't changed since the mandate from 1/floor years ago):
 
1 smoke on each floor/living space, including basements, and 1 in each bedroom/sleeping area (typically defined by having a closet) with one immediately outside and adjacent to the bedroom area. There are other variables, such as if there is a long corridor and if the location of the smoke adjacent to the bedroom (in the case of a 2 story house with master on the 1st floor) dictates more detectors to be installed.
 
They are not required in areas that are not habitable, IE: crawl spaces or unfinished attics...the attics, even if walk up, creates a design issue as any detector installed there would not be within the operating specs of 99% of the manufacturers out there, which would negate it's installation even if an overzealous AHJ dictated one to be installed there.
 
Whether or not the LV units comply for building code has been argued by some AHJ's since these installs that need a host panel forces the HO to "maintain" the system in operable condition and if the panel fails or is powered down (nuisance alarms, etc.) it negates the spirit of the code, while HV units, in their minds, are harder for a HO to "turn off" or bypass (though many have a plug in pigtail now).

 

[szoostrom]

Thanks again for all the input.
 
I spoke with my AHJ; our township code enforcement officer.  He said LV smokes must be monitored.    HV do not need to be but need to be linked.   I live in southeast PA and he indicated that's the rule in most if not all of PA.   My system is not monitored so I didn't ask for reasoning to see if there's a work around for me to put in LV.   I figure it's the same as DEL described in last paragraph of July 9 post.   I'll go ahead with HV smokes and put a relay into my controller.   And use lithium batteries as suggested by AZ1324.
 
AHJ also suggested combo smoke/CO.   I'm thinking I'd be better off putting a separate LV circuit powered and monitored by the controller for CO.    I have six locations that are wired now and need new smokes.  1. Unfinished basement utility, (1st for furnace),   2. Eating area next to kitchen,   3. Garage,  4. Hallway outside bedrooms,  5. Finished Attic area,  6. Unfinished attic utility (2nd floor furnace).    I have easy access to furnace areas in attic and basement.  I'm thinking those are the only places that really need CO.
 
Any thoughts on where CO should be placed ?  and if it's better to get a combo detector or put in separate loops ?  - are welcomed.

 

[apostolakisl]

Thanks again for all the input.
 
I spoke with my AHJ; our township code enforcement officer.  He said LV smokes must be monitored.    HV do not need to be but need to be linked.   I live in southeast PA and he indicated that's the rule in most if not all of PA.   My system is not monitored so I didn't ask for reasoning to see if there's a work around for me to put in LV.   I figure it's the same as DEL described in last paragraph of July 9 post.   I'll go ahead with HV smokes and put a relay into my controller.   And use lithium batteries as suggested by AZ1324.
 
AHJ also suggested combo smoke/CO.   I'm thinking I'd be better off putting a separate LV circuit powered and monitored by the controller for CO.    I have six locations that are wired now and need new smokes.  1. Unfinished basement utility, (1st for furnace),   2. Eating area next to kitchen,   3. Garage,  4. Hallway outside bedrooms,  5. Finished Attic area,  6. Unfinished attic utility (2nd floor furnace).    I have easy access to furnace areas in attic and basement.  I'm thinking those are the only places that really need CO.
 
Any thoughts on where CO should be placed ?  and if it's better to get a combo detector or put in separate loops ?  - are welcomed.

 
 
Why aren't you monitoring?  It is not expensive, around $9/mo.  That is a small price to pay to protect your property from fire/burglary when not home and protect your life when you are.