Fire Alarm Circuits Between Buildings

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gadfly56

gadfly56

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New Jersey
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Professional Engineer, Fire & Life Safety
Does anyone have any experience running an SLC between buildings? The manufacturer (Siemens) allows this. Tech support said I could only go underground, and pointed me to article 225 (2005 NEC), but that seems to be for power circuits, not power-limited communication circuits. In addition, they require that this portion of the SLC be shielded (it normally doesn't have to be), and the tech didn't seem to understand when I asked if RMC would be adequate for shielding.

I took a look at 760.11 which points me to 800 parts II, II, and IV or 300 part I. I'm having trouble visualizing the implementation of the various article requirements. Can anyone give me a list of materials, installation method/sequence, and a primer on how they meet the article requirements? From what I can tell, I probably will use article 800 but I just don't know. Thanks in advance for any help.
 
It is done often in the areas I work, I have even helped interlink Siemens panels with fiberoptic cables between buildings.

But much more common is having a main building with fire alarm circuits reaching out from that building on copper wire to outbuildings.
 
iwire said:
It is done often in the areas I work, I have even helped interlink Siemens panels with fiberoptic cables between buildings.

But much more common is having a main building with fire alarm circuits reaching out from that building on copper wire to outbuildings.
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Any tips to share? I'm just not sure of the nuts-and-bolts "how to". And its copper in this case, although I've got a bunch of D2300CPS's in the network. Offhand I'd say run a wet location rated cable in 3/4" or 1" RMC and bury it 24" down and then ground at both locations. But I can't determine if I can use Fuseless Primary Protection or not and what parts I need let alone how they go together.
 
gadfly56 said:
Any tips to share? I'm just not sure of the nuts-and-bolts "how to". And its copper in this case, although I've got a bunch of D2300CPS's in the network. Offhand I'd say run a wet location rated cable in 3/4" or 1" RMC and bury it 24" down and then ground at both locations. But I can't determine if I can use Fuseless Primary Protection or not and what parts I need let alone how they go together.
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Surge protection where it exits and enters the building is a must for copper ( NEC 760.32). Such as a product from http://www.ditekcorp.com/products-app-guides-details.asp?pkCategoryID=73&fkAppGuideCatID=73

I'd also run it in PVC, but that's a personal choice. Less chance of ground loops between the buildings and less chance of lightning being a problem. I would go 1" or larger, after all the bigger the easier the pull. There is direct burial rated cable fire alarm rated cable (honeywell/genesis cable) http://www.genesiscable.com/producttemplate.asp?Page=760.8.

I prefer IMSA cable http://www.belden.com/pdfs/Catalogs/IMSA%20Cat.pdf, I have pulled in miles of it for UG fire alarm, and not once has it ever failed. It is more $ than Genesis Cable. Its kinda like SO cable, but the jacket is more rugged and has an internal plastic jacket. Highly recommended, even if its not rated as FPL. Options include twisted and shielded, and solid conductors.
 
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dbuckley said:
Tips - don't ground both ends of the shield, as then you put the shield in parallel with the MGN, and it'll carry current, electricity using all paths 'n all.
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I understand about not grounding the cable shield at both ends, but I thought you had to ground a metallic raceway at both ends.
 
I put plastic weather proof junction boxes where the wire enters and leaves the buildings, 1" pvc between the boxes, surge protector on each end, and a ground rod on each end for the surge protectors. I use a shielded outdoor rated wire. Also connect the shield wire to the surge protectors.
 
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