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#172270 - 12/17/07 05:01 AM Fire Alarm Cable Support....
Elec N Spec Offline
Member

Registered: 07/06/06
Posts: 33
Loc: Rochester Hills, MI USA
Article 760.8 requires that fire alarm cables and conductors be supported by the building structure. I would like to hear what others think regarding supporting the fire alarm cables from the suspended ceiling support wires. Tony

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#172278 - 12/17/07 08:11 AM Re: Fire Alarm Cable Support.... [Re: Elec N Spec]
sparkyinak Offline
Member

Registered: 07/08/07
Posts: 1286
Loc: Alaska
Ceiling support wire is not to support nothing but the ceiling
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#172281 - 12/17/07 10:09 AM Re: Fire Alarm Cable Support.... [Re: sparkyinak]
George Little Offline
Member

Registered: 01/18/04
Posts: 1492
Loc: Michigan USA
Guys- take a look at NFPA 70 - '05 Edition and check at 300.11(A)(1) & (2) and note that in some cases wiring methods are permitted to be supported by the same support wires that support the ceiling. Now- depending on your definition of "exposed" you might be able to support the cable via the support wires for the ceiling. It would be handy especially if the structural ceiling was 10 feet above the suspended one. I for one would feel comfortable if the suspended ceiling did not have removable panels. If the suspended ceiling had removable panels, my understanding is that this is considered exposed wiring and subject to physical damage due to "normal building use" 760.8. So Tony, "Write it"


Edited by George Little (12/17/07 10:11 AM)
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#172287 - 12/17/07 01:58 PM Re: Fire Alarm Cable Support.... [Re: George Little]
sparkyinak Offline
Member

Registered: 07/08/07
Posts: 1286
Loc: Alaska
The original posts asked if the support wires for a hanging ceiling can support the FA cable. If the hanger wires are there to support the ceiling the those wires can not be used. A drop ceiling is not considered part of a building structure.
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#172317 - 12/17/07 07:00 PM Re: Fire Alarm Cable Support.... [Re: sparkyinak]
gfretwell Offline

Member

Registered: 07/20/04
Posts: 9012
Loc: Estero,Fl,usa
Fl IAEI had a long discussion about this around 1996? when this first showed up in the code. They decided if there were extra wires, beyond what held the ceiling up, you could use these supplemental wires for support. Then the question became, which wires were holding up the ceiling and which ones were extras for wiring method support. They decided common sense would prevail and you should be able to spot the pattern the ceiling guys used and identify the extras.
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#172319 - 12/17/07 07:04 PM Re: Fire Alarm Cable Support.... [Re: sparkyinak]
leland Offline
Member

Registered: 08/20/07
Posts: 856
Loc: Lowell area, Ma. USA
No, The way I read it.
760.8 refers to surface applications and 300.4.D. Ok.
Now go to 300.11 (A) (1) &(2).
There's the answer.


Edited by leland (12/17/07 07:06 PM)

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#172320 - 12/17/07 07:07 PM Re: Fire Alarm Cable Support.... [Re: leland]
leland Offline
Member

Registered: 08/20/07
Posts: 856
Loc: Lowell area, Ma. USA
Additionaly, you must determine what type of wire/conduit you are useing

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#172334 - 12/17/07 08:43 PM Re: Fire Alarm Cable Support.... [Re: leland]
George Little Offline
Member

Registered: 01/18/04
Posts: 1492
Loc: Michigan USA
The more I read this thread, the more I learn about fire alarm wiring above drop ceilings. I've decided that it can be there and would not have to be fastened directly to the structural ceiling but could be on hangers or similar fittings and when this is the case, one would have to look at 300.11 (A) (1) & (2). I said this previously and was echoed by Leland but there is an additional concern in 760.7 that need to be heeded.
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#172415 - 12/19/07 04:14 AM Re: Fire Alarm Cable Support.... [Re: George Little]
resqcapt19 Offline
Member

Registered: 11/10/00
Posts: 2209
Loc: IL
When working in the Chapter 7 Articles you have to look for this statement:
 Quote:
760.3 Other Articles
Circuits and equipment shall comply with 760.3(A) through 760.3(F). Only those sections of Article 300 referenced in this article shall apply to fire alarm systems.

In this case 300.11 is referenced in 760.25 and 760.52(B)so the 300.11 does apply.
As far as 760.7 it doesn't say what the CMP intended. They were trying to prevent you from just laying the cable on top of the ceiling, but the section wording does not really do that. The wording only says you can't prevent the removal of the ceiling tiles. A few fire alarm or any other type of cables would not prevent the removal of the tile. The section should just say that the cables cannot be supported by the tiles or the grid, but it doesn't so now it is a subjective rule as to how many cables can be placed on the tile before it becomes impossible to remove.
Don
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#172416 - 12/19/07 05:03 AM Re: Fire Alarm Cable Support.... [Re: resqcapt19]
George Little Offline
Member

Registered: 01/18/04
Posts: 1492
Loc: Michigan USA
Thanks Don, I missed that and it's a good solid reference to wiring above drop ceilings.

Lets have a good 2008. Things have been kinda rough here in Michigan and we need to turn it around.
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