I was recently asked a question regarding when life safety codes mandate two hour protection of the fire panel. In a general alarm, general evacuation facility, there is no code requirement. In that situation, people get out of the building immediately so there’s no need to communicate with occupants within the building after the fire department arrives. It’s only required in a facility that partially evacuates or relocates its occupants (hospitals, high rises, assisted living facilities, etc.). In this situation there is a need for continuous communication with people that are in areas of refuge within the building for some time. This communication is usually accomplished by voice messages over an Emergency Voice/Alarm Communication System (EVACS), but it may simply be horns and strobes. In order to ensure continuous operations, the control equipment has to be able to survive an attack by fire for at least two hours. The code references are, of course, not found in one place or spelled out in black and white. The first reference for voice based systems is found in NFPA 72 Chapter 24.3.6.4.1 which states:
24.3.6.4.1 For systems employing relocation or partial evacuation, a Level 2 or Level 3 pathway survivability shall be required.
It’s important to remember that pathway (or circuit) survivability includes the source of the pathway’s function (speaker, strobe, chime, etc.). It doesn’t do much good to protect the field circuit if the source of notification is inoperative, so the survivability requirement applies to the amplifiers, power supplies and circuit boards that are connected to the pathways. That requirement isn’t just a reasonable inference. That’s a code requirement found in our second reference, NFPA 72 Chapter 24.4.2.8.5.3 & 4:
24.4.2.8.5.3* All circuits necessary for the operation of the notification appliances shall be protected until they enter the evacuation signaling zone that they serve by the protection provided by the pathway survivability level required in 24.3.6.4.1 or by performance alternatives approved by the authority having jurisdiction.
24.4.2.8.5.4 Where the separation of in-building fire emergency voice/alarm control equipment locations results in the portions of the system controlled by one location being dependent upon the control equipment in other locations, the circuits between the dependent controls shall be protected against attack by fire by the protection provided by the pathway survivability level required in 24.3.6.4.1 or by performance alternatives approved by the authority having jurisdiction.
Our third reference answers the question of what is required to achieve Level 2 or 3 survivability. Level 2 or 3 pathway survivability is defined in NFPA 72 Chapter 12.4.3 & 4, which calls for two hour fire-resistive installation methods. Level 3 has the same requirements as Level 2, with the addition of sprinkler protection.
The above requirements apply to a voice based evacuation system. What if a tone based notification system is utilized? Our fourth reference addresses that in NFPA 72 Chapter 23.10.2 (the asterisk indicates an appendix note shown below):
23.10.2* Fire alarm systems used for partial evacuation and relocation shall be designed and installed such that attack by fire within an evacuation signaling zone shall not impair control and operation of the notification appliances outside the evacuation signaling zone. Performance features provided to ensure survivability shall be described and technical justification provided in the documentation submitted to the authority having jurisdiction with the evaluation required in 23.4.3.1.
A.23.10.2 One or more of the following means might be considered acceptable to provide a level of survivability consistent with the intent of this requirement:
(1) Installing a fire alarm system in a fully sprinklered building in accordance with NFPA 13, Standard for the Installation of Sprinkler Systems
(2) Routing notification appliance circuits separately
(3) Using short-circuit fault-tolerant signaling line circuits for controlling evacuation signals
Handbook note: The requirement for notification appliances to operate in those evacuation signaling zones that are not attacked by fire will also require that circuits and equipment that are common to more than one evacuation signaling zone be designed and installed such that the fire will not disable them. For instance, a signaling line circuit used to control notification appliances in multiple evacuation signaling zones should be properly designed and installed so that one fire would not impair the signaling line circuit, rendering the notification appliances serving more than one evacuation signaling zone inoperative. Power supply requirements of Chapter 10 apply to these systems. The secondary power supply requirements of that chapter meet the intent of these survivability requirements.
This is basically what Chapter 24.4.2.8.5.3 above says. The code itself is prescriptive, but you can see from the appendix note that a sprinklered building is a suggested performance method to achieve survivability in lieu of prescriptive methods, so long as the AHJ signs off on it. In my experience, AHJs don’t vary from prescriptive methods without a good reason because it puts a certain amount of design liability on them. However, it may be accepted in problematic retrofit applications if proactively presented to the AHJ along with enhancing conditions (e.g. method of installation, different paths of egress available, 24 hour staff or security presence and/or the response time of the fire department).
As you can see, meeting this requirement can be expensive, but with an understanding of the applicable code requirements, existing conditions and good communications with the approving authority, costs and structural invasiveness can be controlled to a reletively reasonable amount. As always, remember that the use of Gamewell-FCI life safety products will ensure efficient, reliable, code compliant installations along with experienced advice. Contact us if you have any questions or would like additional information.
Gene Rowe, SET
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