Class B Fire Alarm Wiring

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Old 03-10-14, 03:37 PM
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Class B Fire Alarm Wiring

I'm working on the fire alarm system on the site I'm on, and was wondering how you determine which resistor to use for your EOL on your initiating and signalling circuits?

Also, my jman ran two pipes out of the panel. One for the pull stations and smokes, and a separate one to the nearby sprinkler tree. He figures we can run two feeds off the same terminals in the panel (+/- to tree, +/- to initiating loop). Is this do-able or should I run the sprinkler tree wire to the panel and back up to the nearest 4x4 to t-tap it into the loop?
 
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Old 03-10-14, 10:45 PM
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The EOL resistor is easy, you have use the value specified by the alarm panel manufacturer. Generally the EOL resistors are included with the panel or any add-on expander modules. I don't know about other manufacturers but the Honeywell-Ademco panels use different EOL resistors on the zone expander modules than on the main panel.

I don't know what a "sprinkler tree" is so I can't help in that area.
 
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Old 03-10-14, 11:22 PM
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The EOL resistor is used at the end of the line. Normally pull stations and smokes are not on the same circuit unless you are using a data loop.

Running two conduits from the fire panel is correct as horn/strobe wiring should not be mixed with initiating wiring.

Is this a monitored fire alarm system ? Here in the states, no one messes with a monitored fire alarm as that constitutes a breach of contract and opens a major liability issue. I service/install many commercial systems. No one can legally service/modify my alarm system. Just as I can't work on another companies system.
 
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Old 03-11-14, 04:00 PM
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I looked high an low on the panel and in the manual, couldn't find any info on the EOL. I might just wait for verification day on Monday and ask, then quickly go slap them in. Everything else is installed I'm just not sure which value resistor to put in. We do a lot of Edwards systems. I'm unsure if Troy Edwards operates in the US.
The sprinkler tree: I'm not a sprinkler guy so forgive my terminology if it is incorrect, but its the main "feed" for the fire sprinklers. The FA system monitors the flow and tamper switches on the tree.
Pj, we usually run everything in one pipe and have the wires pass through where not needed to tie in a device. We do the complete install and the fire dudes just come and verify everything is working. I've never done service on an FA system but I think whenever something craps out, an electrician is called and the manufacturer has to re-verify afterwards.
The issue isn't two separate pipes for the systems. There is a pipe exiting the panel to feed the building (both init and sig in that pipe), and a separate one exiting the panel for the sprinkler tree instead of the first pipe running through the pump room. I guess to simplify what I am asking, is there a difference between t-tapping the tree and running two +/- off of the same terminals in the panel?

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Old 03-11-14, 04:27 PM
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We'd call it the sprinkler riser.

You are an electrician following a set of wiring plans for the fire alarm system. Here we call it "parts and smarts". The alarm company supplies the smarts..... diagrams and specs....and the electrician runs the wiring based on this. After the wiring is completed the alarm company will come in and install devices and program the system. (sometimes just program and test)

Edwards systems are usually a data loop system where you would run one pair of wires to each device..... daisy chain. Each device is programmed for or has its own unique address. A data loop system does not use an EOL resistor as each device is supervised.

If this indeed a data circuit then your first picture is correct and you would not see an EOL listed for initiation since none would be needed.

With a data loop system.... T tapping is permitted but when I supply the "smarts" to an electrician I specify no T tapping. The reason for that is that in the case of troubleshooting.... it makes it much easier to follow the circuit.
 
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Old 03-11-14, 05:44 PM
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So the second drawing, as my jman wants to do it, would not be acceptable?

I'm only 2nd year and fire alarm doesn't pop up in school until 3rd, but this is how I understand it PJ...

I understand addressable devices in both A and B systems. Thats all I have seen so far.
In a class A, you run +/- out of the panel in to a device, and a +/- out, then in, out etc. and finally back to the panel. Should a device crap out or a wire be severed, the panel splits into two class B circuits with the last working device acting as an EOL, therefore allowing the panel to tell you exactly what crapped out. My very first FA job I was given a small office building the past fall to do myself, and this is how I did it and it all worked without deficiency.
This is only my 2nd FA job and I'm sharing it with my jman this time. It is a class B and as I understand, you run your +/- out of the panel and either in to the device and +/- out, or t-tap (only on initiating). The end of line is required because it will have a higher resistance than the devices on the loop which the panel will read as normal. Should a device conk out, the panel has lost its link to the resistor and reads the smaller resistance of the last working device, which tells it there is a problem.
Am I way off here?
And again, I refer to my first sentence, which I am most curious about.
 
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Old 03-11-14, 06:16 PM
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As far as I know..... a data loop system is class B wiring. You don't return the +/- back to the panel.

Data loop wiring doesn't need to be supervised. Each device on the data loop has its own unique address and communicates with the panel. The panel know instantly when a point goes missing. So if the wiring opened in the middle of the loop..... anything after the break would be missing.

If you wired the points in a daisy chain..... you'd know where to look for the problem.
 
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Old 03-11-14, 06:57 PM
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The devices we are using are addressable. So this means the eol is not needed? That could explain why I can't find any info on the eol or the resistor supplied as furd was talking about.
However, Edwards sent us a half dozen eol plates but each comes with about 10 different resistors. If they were not needed, why would they be sent?
 
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Old 03-11-14, 07:59 PM
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EOL resistors are needed with standard zone inputs and also with horn/strobe circuits.

I'm not quite sure what an EOL plate is.
 
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Old 03-12-14, 12:36 AM
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From what I remember there are two wire (addressable loop) and four wire (conventional zone+power) initiating circuits, and then the two wire NAC is separate. I learned two wire devices still need to be run serially (with ins and outs) for loop integrity supervision and T-tapping was not allowed.

And also from what I remember two wire initiating circuits still have an EOL RESISTOR across the last device, but since as you already mentioned the panel would detect the loss of a station immediately, it is mainly to shunt signal reflections in the wiring that could cause unwanted behavior.

Only 4-wire initiators need the EOL RELAY (which would be these 'plates' - I'm picturing an EOL relay mounted to a 2-gang plate or something similar), in order to supervise the power lines. The principle is that if the power is interrupted at any point in the line, the EOL relay cuts out, which removes the EOL Resistor from the circuit and turning on the Trouble light at the FACP/annunciator.

But things probably have changed since I went to school..
 
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Old 03-12-14, 03:42 PM
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PJ,

http://www.mircom.com/components/com...ecc0b28062.jpg

That is the plate I am talking about. There are 4 terminal screws on the back for the incoming +/- and the resistor itself.
I appreciate the help guys but I still don't have clear answers on how to figure out which resistor to use, and if the sprinkler tree wiring is acceptable. I'll wait and talk to the Edwards guy on monday and post back here.
 
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Old 03-17-14, 03:46 PM
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So verification day was today and the only deficiency was the flow switch my jman wired incorrectly. Got my answers though...

The EOL resistors, as Furd said, came in the panel already. They were installed to keep the system clear for the horn strobe circuits until the horn strobes were tied in. We just had to match the ones in the panel. And apparently if they were to go missing for whatever reason, somewhere in the depths of the manual there is a note on what the panel expects to read for resistance.
As far as the tree wiring, the method my jman used is acceptable but not preferred as this means fitting two wires under each terminal. So I ran the tree circuit back up to the nearest 4x4 and t-tapped it in, which is also acceptable but ideally even in a class B they would prefer to see in/out.
Thought I'd post my results for any future readers!
 
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