Replacing the phone lines on a fire alarm panel

How fire alarm panels use phone lines

A panel with a digital alarm communicator transmitter (DACT) dials the monitoring center over a phone line and sends a short coded message: alarm, trouble or supervisory. Older installations use two copper lines so that one failed line doesn't silence the panel.

When the copper goes away, the panel either gets a new communicator (cellular or IP) or keeps its dialer and plugs into a device that gives it a dial tone over cellular, such as Ooma AirDial.

What NFPA 72 allows

NFPA 72 is the national fire alarm code. Your state or city adopts a particular edition, sometimes with local changes, so the rules that apply to you depend on where you are. In editions since 2010:

• Signals can be sent over technologies other than two phone lines, including cellular and IP.
• A single communication path is permitted unless your enforcing authority prohibits it. That path must be supervised at least every 60 minutes, with a failure reported to the monitoring center within 60 minutes.
• With two paths, each path is supervised at least every 6 hours, and one technology (for example two cellular carriers) can provide both paths.
• Since the 2013 edition, a DACT is used with one phone line plus a second path such as cellular or radio. A second phone line is only an exception where nothing else is available and the authority approves it.

Sources: Bellevue, WA DACT interpretation quoting NFPA 72.pdf), Minnesota State Fire Marshal, NFPA TIA 25-1.

Battery backup

A communicator that is part of the fire alarm system follows the panel's secondary power rule, which is commonly 24 hours of standby plus alarm time. Shared communications equipment outside the panel needs 24 hours of backup, or 8 hours where the authority accepts a risk analysis. Check the exact requirement in the edition your jurisdiction uses, and compare it to the published runtime of the device you are considering.

Source: North Carolina Department of Administration POTS replacement requirements.

UL 864 and other listings

UL 864 is the listing standard for fire alarm control units and their accessories, including communicators. Authorities generally expect the transmission equipment to be UL 864 listed. A listing is about the device; whether an installation meets NFPA 72 is decided by your authority for that building.

Ooma says AirDial is UL 864 and UL 62368-1 certified and approved as a cellular communicator by the California State Fire Marshal (Ooma compliance datasheet). Minnesota's fire marshal recommends against ordinary VoIP for fire alarm signals.

Steps to replace the lines

• Find which phone numbers the panel uses. Your monitoring company can tell you.
• Ask your fire marshal (the authority having jurisdiction) which NFPA 72 edition applies and whether a single cellular path is accepted.
• Check the cellular signal where the panel is. Panels are often in basements and electrical rooms.
• Choose the replacement: a new communicator from your alarm company, or a dial-tone device such as AirDial so the panel keeps its dialer.
• Install, then test every signal type with the monitoring center: alarm, trouble, supervisory and the periodic test signal.
• Only then cancel the copper lines. Keep the test results with your inspection records.