Wiring Diagram Aids in Explaining ‘Survivability’
With the “when” clarified, the application needed explanation for the implementation of these circuits. From several conversations and numerous questions, here are the results as they affect both vertical and horizontal zoned facilities. A diagram has been created to show visually what would easily take many pages to explain in detailed text. Remember, this is for a voice evacuation system that is geared toward partial evacuation notification as would be found in high-rises and most hospitals. 

The associated diagram will begin the design requirements from the fire alarm control panel (FACP) and any remote audio/visual source. The wire assumed for this example is power limited fire alarm (PLFA) wire. Similar requirements are needed for nonpower-limited fire alarm (NPLFA) wire as well. It should be assumed that no notification circuit, be it audio or visual, provides notification in more than one zone of alarm. 

The intent is the audio and visual circuits, which originate from the FACP and route in the same zone of notification as the FACP, are not required to have the two-hour survivability rating. Also, with the source from the FACP, the audio and visual circuits that notify any adjacent zones to the FACP zone are not required to have the two-hour survivability rating. This is attributed to the fact that none of these circuits traverse through an intermediate zone to get to the zone of notification. 

Continuing, an audio or visual circuit that originates at the FACP and travels through a zone that it does not provide notification for, is required to have the two-hour survivability requirement until it arrives at the zone of notification. This is to provide survivability of those notification circuits that provide an alert to a potentially unrelated zone of incidence. This survivability allows for the audio and visual notification of those zones to indicate evacuation or further instruction to those occupants if the need should arise. 

As depicted with a notification appliance circuit (NAC) panel in the 5th zone, the visual circuits that lead from that panel to two different adjacent zones, as stated with the

FACP, are not required to have the two-hour survivability rating. However, the audio circuits that originate from the FACP zone with a few zones of separation are required to h
ave the two-hour survivability rating to the zone of notification.

A question that can be confusing to answer: When does the survivability requirement end? Answer: Once the circuit enters the zone in which it is to control the audio and visual devices. The circuit no longer is required to maintain the two-hour rating. It can then revert to a normal fire alarm circuit using the specified PLFA wiring methods and route through the area as needed.

One issue that can quickly be under question, and should be in full compliance, is the portion of a circuit that controls the remote NAC/amplifier panels. They are required to have the survivability between the FACP and the remote panels if they are not in adjacent evacuation zones. For our example diagram, the circuit that controls the NAC panel is required to have the two-hour survivability from the FACP to the NAC.

To date, this has been the best presented reference with a graphic to help describe and understand when and where the requirement for the two-hour survivability affects the activation of the Section 6.9.4 survivability requirement and the use of the two-hour survivability circuits. No doubt that other circumstances will arise that will question this interpretation, but this has been suggested, engineered and used in existing facilities faced with the requirement to update a FACP and voice evacuation system to current 2003 IBC/IFC and 2002 NFPA 72 requirements.

Latest Edition of NFPA 72 Offers 5 Ways to Meet Requirements

For the new 2007 edition of NFPA 72, this section again has been modified and expanded to hopefully provide a clearer use of survivability. This section has been renumbered to Section 6.9.10.4.2 and there are now five possible ways to satisfy the survivability requirements: 1) two-hour fire rated -CI cable; 2) two-hour fire rated cable system; 3) two-hour rated enclosure; 4) performance alternatives approved by the AHJ; 5) buildings fully sprinklered in accordance with NFPA 13 and the wiring enclosed in a metal raceway in accordance with the NEC Article 760.

As you progress through the editions of NFPA 72, one of the original options has been split out and the option with -CI cable now gets its own bullet. But the added option that will have the most impact is adding a fully

sprinklered building with all the pertinent wiring in conduit. Since most buildings are fully sprinklered, as required by the building codes for most high-rises and hospitals, the option of putting all those circuits in conduit would, on the surface, seem as the least expensive option and the easiest for the fire alarm contractors to install.

The fifth option would no doubt be used most since the fire alarm and detection drawings are submitted long after a construction bid has been issued and the design of the building s complete. Since the building cost is paramount to the owner, all these options need careful consideration as to he cost and time required for installation.

They also need to be presented early in the building design to ascertain the best method to use in order to provide the code compliance system as required by Section 6.9.4.

In many states it is the electrical inspector who is charged with the inspection and acceptance of the conduit and wire system. Therefore, any potential two-hour rating will need to have the conduit and wire inspected prior to any covering of this equipment. However, it is usually the fire department inspector who accepts the operation of the system and signs the all-important Certificate of Occupancy card.

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