Commercial Fire Telephone Lines

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rdbutler

rdbutler

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I have always known that a commercial fire alarm system that is monitored off site requires two phone lines (primary and backup). But today when I was asked to cite the code that this comes from, I was unable to find it.

Can someone tell me what code talks about the requirement for two phone lines for commercial fire alarms?

Thanks in advance.

-Russ
 
jtester said:
This is the first time I heard of it. Is it a local thing?

Jim T
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Jim I don't know the code but any fire panel I have worked on in this area that uses phone lines for communication has a primary and a back up phone line.
 
Bob,
Are you talking about panels that dial out or ones that are hard wired to a central station? The hardwired ones around here only use a single leased pair.
Don
 
iwire said:
Jim I don't know the code but any fire panel I have worked on in this area that uses phone lines for communication has a primary and a back up phone line.
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Don't know about the code either, a brief flip through my copy of NFPA Pocket Guide to Fire Alarm System Installation didn't reveal much except saying that the DACT must have two lines of communication, one of which must be a telephone line. I found that in a note, not an actual code.

Thats pretty much the norm here in Los Angeles so I'm guessing its a nationwide thing.
 
don_resqcapt19 said:
Bob,
Are you talking about panels that dial out or ones that are hard wired to a central station? The hardwired ones around here only use a single leased pair.
Don
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Dial out.

I don't think I have ever run into a leased line connection.

Much more often we install radio master boxes.

The redundancy of two phone lines was always a joke to me as they are often run all the way from the panel right back to the tel office in the same cable.

Seems highly likely if you lose one you will lose both.
 
Nfpa 72

Nfpa 72

NFPA 72 - The National Fire Alarm Code will give you all the info you need concerning the requirements for phone lines.
See 8.5.3.2.1.4 for systems using a DACT and the requirements for backup.
IWire - Down here, they don't know what a Master Box is. When I showed a couple that I had brought from Mass, it was like showing fire to a caveman. Wonder and Awe.
 
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New NFPA 72

New NFPA 72

Thanks DEZ!

Except that I already gave away my 2002 version of NFPA 72 so I had to borrow it back. However, the code you quoted is now in section 8.6.3.2.1.4 of the 2007 version (Which is being adopted in Oklahoma as of September 1st).

And IWIRE, I agree that the two telephone lines are likely to be in the same trunk and if one gets cut they both will.

Thanks to all for your comments. Please consider this thread dead.
 
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Ul / Ulc

Ul / Ulc

The two-line dialer requirement was insurance-driven and generated by UL / ULC. The specification actually requires two different trunks for the two lines. Some AHJ's require them to be supplied by two different carriers as well, but this is local. Generally speaking the other posters' comments on the uselessness of two-line dialers is accurate, although we have had many actual instances in which the second line at a premise was used to notify us that the first line had dropped out.

This is all going to be supplanted soon by newer technology, namely supervised monitoring [typically over the internet]. The communication between the premise and the monitoring station will be polled at very short intervals [seconds] and any loss of communication will generate an immediate trouble at the central station. This is much better than any sort of unpolled connection [like a two-line dialer or cell phone transmitter] because the latter generally go 24 hours between dial-up check-ins.
 
iwire said:
The redundancy of two phone lines was always a joke to me as they are often run all the way from the panel right back to the tel office in the same cable.

Seems highly likely if you lose one you will lose both.
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Don't do any fire work myself, but I know our church has a truly redundant system... one land line, the other cellular based.

We know for a fact that the redundancy is necessary since the cellular trips an obnoxious fault warning indicator on a regular basis when the signal fades. :roll:
 
redundant comms

redundant comms

This illustrates the problem with cellular as a backup medium for Fire Alarms, especially since the supervision of cellular connections is generally set for 24-hour check-in. When you need it most it might not be there.

Cellular is handy on the security side, however. There have been many instances in which burglars have cut the hardwire comms [phone, internet] before a break-in. The central station gets a comm fail and dispatches guards to the site. The guards or police drive around the site, see nothing, and leave. The burglars, who are inside the premise, wait until the responders leave and then make their escape. Unlike a cut hardwire connection, cellular or other wireless media keep transmitting alarm events until the bad guys rip the transceiver off the wall.

I wouldn't rely on cellular for a life-safety application like Fire unless the supervision period was set short enough to be useful. This is a good example of a situation where you could be code-compliant or even meet UL/ULC and still not have adequate protection.
 
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