Using existing/abandoned 120vac wire for Fire Alarm?

[Security101]

I know I saw it some where (not sure if here or in 70 or 72) and I searched and cant find it.

I saw where you can use old existing 120vac wiring for power limited Fire Alarm installation. I just cant remember if it was just a smoke detector designed for this purpose, or a new system designed for it, or what.

I have a guy asking on another forum if I've dealt with it before. I've searched NFPA/NEC and either I'm not using the correct search terms - or the info i'm looking for is incorrect.

I would think if it is true one would have to verify all the splices, inspect, test and mark in red everything, yes? I guess it's designed to limit having to wire older buildings where retro work may be impossible. Maybe it's just reusing the old 120vac smoke circuits, I don't know...

What do you know? Please reference code where available (I cant look up 2008 yet :wink

Jim

 

[gadfly56]

You may wire fire alarm circuits as either power limited or non-power limited. Power limited utilizes FLP, FLR, or FPLP rated wire and is wired per NEC 760, 770, and 800 as applicable. If you choose non-power limited, then all the requirements of article 300 apply and you have to mark all your circuits as non-power limited from the FACP out to the devices, including at all junction boxes. This is where you might re-use existing EMT/RMC and the conductors to wire in your low voltage devices where the current multi-station fire/heat alarms are installed.

You should be aware that this is feasible only if you're putting in a conventional low voltage fire alarm. Addressable systems, as a rule, require twisted or twisted shielded wire.

 

[Security101]

I wonder about notification appliances and the like, I mean could the whole system be based on the old wiring, as long as it's a conventional low voltage system?

I actually will have to check now that you brought up addressable too, as I think I read in some of my catalogs where there is a system made for this application - without the twist!

Hummm
Jim

 

[MichaelGP3]

I just knew that k&t would be making a comeback someday!

On a related note, are homing pigeons acceptable as a secondary means of alarm transmission?

 

[mdshunk]

I've done it for replacing primative systems with 120V pull stations and 120V gongs with similarly primative low voltage systems. Just a bigger wire size than necessary, so I thought, "no big deal". I'm curious now about these remarking requirements.

 

[Stallzer]

Using THHN or similar wire is fine, I'm assuming it's in EMT Conduit ? Some of the newer addressable FACP's such as Silent Knight's 5820XL will even run the SLC on THHN as twisted/shielded pair wiring is slowly being phased out.
For Notification circuits I'd actually prefer to use THHN wire as opposed to a FPLP jacketed cable due to the stronger insulation of the THHN making it more difficult to cause ground faults.

 

[mdshunk]

....For Notification circuits I'd actually prefer to use THHN wire as opposed to a FPLP jacketed cable due to the stronger insulation of the THHN making it more difficult to cause ground faults.

Very interesting. How do you suppose the fire alarm cable is getting damaged? People working above ceilings being abusive to it? I know that when I'm above ceilings, I have no idea what half the low voltage cable actually goes to most of the time. I just get it out of my way to do what I gotta do.

 

[Stallzer]

Very interesting. How do you suppose the fire alarm cable is getting damaged? People working above ceilings being abusive to it? I know that when I'm above ceilings, I have no idea what half the low voltage cable actually goes to most of the time. I just get it out of my way to do what I gotta do.

It's not above the ceiling that I'm worried about, it's the pushing / coiling of the cable in the back box. Usual mounting is a 4" square / 1900 box with a 1 gang ring and being as the back box is metal it makes it very easy to nick or damage the cable as it is being pushed into the BB at the time of the appliance installation.

 

[peter d]

NM cable would not be allowed for fire alarms systems where I live. Our local codes very clearly call for FPLP cable or FPLP MC cable, or THHN in raceways.

 

[ypick]

I've retrofitted many fire alarm systems to addressable using existing THHN with no problems. I would recomend meggering the wiring.

 

[Security101]

Thanks for all your replies guys, I feel more informed. I still cant find the "new panel" I saw in one of my mags that is designed for this...

Jim

 

[Weaver Road]

I recently (2 years ago, wow time flies) witnessed a retrofit of an old library with all the 120v circuits in emt cast in the structure (1970s). A full Simplex 4100U system was used and 800 of the initiating devices (smoke, heat, pull) were on the old wires. There have been no problems to this point.

Notification devices and the other 300 initiating devices were run on an entire new set of circuits (risers, NAC panels, wiremold, and custom painted emt) as the old setup was not compatible, nor was it located in half the places that we needed notification, such as visual notification in the lavs, etc.

 

[brennan]

Most systems you can do this. You just have to be care full because you do not know what is t-tapped or what not.

 

[ElectronDance]

I can't think of a problem with it. It would really be no different from pulling THHN for a new system, which is done all the time. as mentioned by others, THHN is superior in some ways, specifically durability. It is also quite a lot cheaper than FPLP.

there are a few things to consider before you jump in however. If you are installing an addressable system, check the manufacturer specs. Some will work fine with THHN, some won't. Also, if you are usuing speaker units, instead of temporal horns, you would be advised to use sheilded twisted pair for the voice circuit, as EMF can play heck with the transmission quality.