Class A fire alarm system

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Alwayslearningelec

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NJ
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The spec says 1. Network data communication wiring shall be run via a data signaling line circuit which shall be run as NFPA standard 72 style 7,two conduit system( return wire shall be run via a separate path).

Questions.

1. What does that exactly mean? A separate conduit for the return loop.
2. Are there any special wiring requirements for Class A
 
iwire

iwire

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Location
Massachusetts
horsegoer said:
The spec says 1. Network data communication wiring shall be run via a data signaling line circuit which shall be run as NFPA standard 72 style 7,two conduit system( return wire shall be run via a separate path).

Questions.

1. What does that exactly mean? A separate conduit for the return loop.
2. Are there any special wiring requirements for Class A
Click to expand...

1) It means you leave the FACP with a conduit, run that conduit to all initiating devices one after the other and eventually you come all the way back to the FACP.

2) Plenty.
 
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A

Alwayslearningelec

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Location
NJ
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Estimator
iwire said:
1) It means you leave the FACP with a conduit, run that conduit to all initiating devices one after the other and eventually you come all the way back to the FACP.

You come back n a separate conduit, correct?


2) Plenty.
Click to expand...
can you name one or two biggies? Thanks
 
N

nhfire77

Senior Member
Location
NH
horsegoer said:
The spec says 1. Network data communication wiring shall be run via a data signaling line circuit which shall be run as NFPA standard 72 style 7,two conduit system( return wire shall be run via a separate path).

Questions.

1. What does that exactly mean? A separate conduit for the return loop.
2. Are there any special wiring requirements for Class A
Click to expand...

Your overlooking the important part: style 7. This is the key here, yes it's a class A loop, goes out comes back, but: Style 7 oh the humanity!

Style 7 means an isolator module on either side of every device and one between the panel and
the first/last device, this triples the number of devices and more than triples other materials and man hours.

Actually it's more complicated it means the slc must still function during the abnormal condition of wire to wire short. Usually isolators solve this.

You really need a FA guy to look that over before you bid it, that's not a Straight forward fire alarm.

You may need to add isolators between floors rooms etc, the spec would have a lot of details.

Class A also has spacing requirements.
 
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gadfly56

gadfly56

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Location
New Jersey
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Professional Engineer, Fire & Life Safety
horsegoer said:
can you name one or two biggies? Thanks
Click to expand...

If you look in NFPA 72-2007, at A.6.4.2.2.2 you'll see a recommendation that if the out and back of the loop are installed one above the other that the minimum separation be 12 inches, and if horizontally, 48 inches.

You can run the out and back in the same conduit for not more than 10 feet when leaving the panel.

Where all wiring is required to be class A (alarm, network, notification) use separate conduit systems for each. When (not "if") the customer makes changes, you don't face the prospect of pulling multiple systems out of the conduit to add a single smoke detector.

For conventional fire alarm panels the alarm circuit is an "indicating device circuit" (IDC) and for an addressable panel it is a "signal line circuit" (SLC). The choices for an IDC are much more limited than an SLC. Style 7 is the most expensive and applies only to SLC loops. For Siemens products, VERY expensive. In their XLS line, the maximum number of isolator modules is 15 per SLC circuit. Silent Knight, on the other hand, doesn't care.
 
gadfly56

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Style 7

Style 7

Digging around a bit, I see that with Siemens, the network interface card (NIC-C) operates as Style 7 when installed with Class A wiring, one pair out and one back, but you have to hit the card coming and going.

The voice network card (DAC-NET), on the other hand, requires two pair out and two pair back for Style 7, but only requires a simple return back to the panel for each pair. The bear of it is that you can't use a 4-conductor cable to make your life easy; must be separate pairs.
 
A

Alwayslearningelec

Senior Member
Location
NJ
Occupation
Estimator
nhfire77 said:
Your overlooking the important part: style 7. This is the key here, yes it's a class A loop, goes out comes back, but: Style 7 oh the humanity!

Style 7 means an isolator module on either side of every device and one between the panel and
the first/last device, this triples the number of devices and more than triples other materials and man hours.

I just read something that NFPA 2010 did away with styles. Is that true? So your saying there is module(device) next to EVERY device?? Which devices, initiating/notification?

Actually it's more complicated it means the slc must still function during the abnormal condition of wire to wire short. Usually isolators solve this.

You really need a FA guy to look that over before you bid it, that's not a Straight forward fire alarm.

You may need to add isolators between floors rooms etc, the spec would have a lot of details.

Class A also has spacing requirements.
Click to expand...
Spacing as far as what? The loops I think, right? minimum 10'
 
A

Alwayslearningelec

Senior Member
Location
NJ
Occupation
Estimator
gadfly56 said:
If you look in NFPA 72-2007, at A.6.4.2.2.2 you'll see a recommendation that if the out and back of the loop are installed one above the other that the minimum separation be 12 inches, and if horizontally, 48 inches.

You can run the out and back in the same conduit for not more than 10 feet when leaving the panel.

But the rest of the out and back are in separate conduits??

Where all wiring is required to be class A (alarm, network, notification) use separate conduit systems for each. When (not "if") the customer makes changes, you don't face the prospect of pulling multiple systems out of the conduit to add a single smoke detector.

For conventional fire alarm panels the alarm circuit is an "indicating device circuit" (IDC) and for an addressable panel it is a "signal line circuit" (SLC). The choices for an IDC are much more limited than an SLC. Style 7 is the most expensive and applies only to SLC loops. For Siemens products, VERY expensive. In their XLS line, the maximum number of isolator modules is 15 per SLC circuit. Silent Knight, on the other hand, doesn't care.
Click to expand...

I still don't get the whole style 7 and isolater modules? Is one really needed for every device.

By the way my FA guy said they want 50% spare capacity so this will REALLY limit the amount of devices per loop. I think he might have said 5 although that sounds impossible.
 
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nhfire77

Senior Member
Location
NH
horsegoer said:
I still don't get the whole style 7 and isolater modules? Is one really needed for every device.
Click to expand...

No, two are except the first and last:

FACP----iso----smoke------iso------smoke----iso------smoke-----iso-----pull----iso----module------iso---back to FACP

horsegoer said:
By the way my FA guy said they want 50% spare capacity so this will REALLY limit the amount of devices per loop. I think he might have said 5 although that sounds impossible.
Click to expand...

"They"? contract document? engineer? Some panels only allow a certain number of isolator modules per loop, but, they normally don't count as a device on the loop, or take an address, but some panels do.

I would allow for as much spare capacity as possible, make it a bigger panel that takes more than 2 SLC cards. If I were to design it, the loops would be short, isolating a area/floor, haxard zone etc. If style 7 is the spec, there is a survivability issue in the design. Unless its a typo or boiler plate and someone forgot to remove that part. You can't Value engineer a style 7 too ,uuch you could suggest its unnecessary and VE it with out the isolators, but I doubt that's an option.

What is the occupancy type of the building?
 
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A

Alwayslearningelec

Senior Member
Location
NJ
Occupation
Estimator
nhfire77 said:
No, two are except the first and last:

FACP----iso----smoke------iso------smoke----iso------smoke-----iso-----pull----iso----module------iso---back to FACP

Wow... So one iso before and after very device like someone before said??


"They"? contract document? engineer? Some panels only allow a certain number of isolator modules per loop, but, they normally don't count as a device on the loop, or take an address, but some panels do.

Contract docs!!

I would allow for as much spare capacity as possible, make it a bigger panel that takes more than 2 SLC cards. If I were to design it, the loops would be short, isolating a area/floor, haxard zone etc. If style 7 is the spec, there is a survivability issue in the design. Unless its a typo or boiler plate and someone forgot to remove that part. You can't Value engineer a style 7 too ,uuch you could suggest its unnecessary and VE it with out the isolators, but I doubt that's an option.

What is the occupancy type of the building?
Click to expand...

It's a college science building.


I must say I have not done much fire alarm but I find it very interesting
 
N

nhfire77

Senior Member
Location
NH
It depends, some panels do not have class A annunciator loops. If, you are asking about horns/speakers then yes.
 
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nhfire77

Senior Member
Location
NH
horsegoer said:
MY FA guy said that no way do you put an ISO module before and after EVERY fire alarm device for the system?
Click to expand...

Look up style 7 class A on google.

Are you sure it's style 7?

Is your FA guy new? They discontinued styles in nfpa 72 2010, but until then there have been styles.
 
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Alwayslearningelec

Senior Member
Location
NJ
Occupation
Estimator
nhfire77 said:
Look up style 7 class A on google.

Are you sure it's style 7?

Is your FA guy new? They discontinued styles in nfpa 72 2010, but until then there have been styles.
Click to expand...

Yes they did discontinue style in 2010 but the spec still calls for Style 7, thats what it says. I would assume it can't be built according to style 7 then, right? No he is not, has been around a long time. What about the iso modules?? One every device? Thanks.
 
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