Best Approach for Cabling Addressable Fire System

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eeee

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I have 50 heat detectors, 10 smoke detectors a tamper switch and a flow switch that I am wiring to an addressable fire alarm panel to include shut down circuits for the 10 air handlers and 4 ventilation fans for the outside ventilation.

Can I wire all 62 of these devices with one big addressable two wire loop containing no isolators? That way, I can do the job with one run of conduit to the devices and back to the addressable fire control panel.
 
Re: Best Approach for Cabling Addressable Fire System

Yes, even the smallest and simplest addressable panels can handle hundreds of devices and can be configured for many applications.

But why would you omit the fault isolation modules? They are an essential part of the system. :confused:
 
Re: Best Approach for Cabling Addressable Fire System

Thanks,

I will include the fault isolation modules. I must define where to put them. The smoke detectors are for the air handlers in the ducts and the one hallway used for egress.
 
Re: Best Approach for Cabling Addressable Fire System

Many systems put them where your loop crosses fire walls/partitions. If you have any of these, it would be a good spot for them. Also, each floor or level of the building should be isolated.

I don't know what code is on the matter, but this is what I've seen in systems I've dealt with. Maybe somebody will chime in with a code ref.

mike
 
Re: Best Approach for Cabling Addressable Fire System

No code requires isolator modules. In addition, no code requires a loop (class A), it could terminate at the last device too (class B).
Most addressable panels can handle 80-100 devices per loop. Some of the newer ones can handle upwards of 200+ per loop.
 
Re: Best Approach for Cabling Addressable Fire System

ron,
are you saying that using a Class A system and/or isolator modules is entirely a design decision?

Trying to learn much more about FA systems!
mike
 
Re: Best Approach for Cabling Addressable Fire System

Mike,
Yes. I'm not saying that you shouldn't do it, but that you don't have to. Probably 99% of addressable fire alarm systems installed in regular commercial buildings are Class B (no return loop and no isolator modules).
 
Re: Best Approach for Cabling Addressable Fire System

Originally posted by ron:
No code requires isolator modules. In addition, no code requires a loop (class A),
Click to expand...
Ron, you know never to say never. :)

mhulbert always check the area your working in.

For instance I believe RI requires any panel used that is capable of class A (which is most of them) to be wired class A. If the panel is only capable of class B the EOL must end up back at the panel.
 
Re: Best Approach for Cabling Addressable Fire System

Originally posted by ron:
Probably 99% of addressable fire alarm systems installed in regular commercial buildings are Class B (no return loop and no isolator modules).
Click to expand...
In regards to class here in MA and RI I would say the opposite is true, we install few if any class B systems.
 
Re: Best Approach for Cabling Addressable Fire System

Ron,

I wonder why anyone would want to install an addressable fire alarm panel with class B. That requirs more cable and conduit, thus more expensive. From a maintenance prospective, it requires more maintenance I have been told, although fault isolation can be more difficult with class A I have been told.
 
Re: Best Approach for Cabling Addressable Fire System

Why would a class B require more pipe? Class A reuquires you to loop back to your FACP at the end of your run, which may be a PITA or no big deal depending on how your wiring is layed out.

As for troubleshooting- if you have the isolation modules in, that helps, and rememeber, you can temporarily turn a Class A into a Class B by disconnecting one side of your loop at the panel and putting an EOL resistor into it. YOur Fire marshall may not go for this if it is a high-risk occupancy though!

mike
 
Re: Best Approach for Cabling Addressable Fire System

Bob,
Your right, I shouldn't say never.
I'll modify my statement, that no national code requires isolator modules. In addition, no national code requires a loop (class A).
Class B signaling line circuit (SLC) is similar to Class A, but no return circuit from the last device back to the control panel. Certain Style Class A SLC loops include the isolator modules.
 
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