Author(s): Wayne Moore. Published on May 2, 2014.

EACH REVISION OF NFPA 72®, National Fire Alarm and Signaling Code, introduces changes to the code for clarification, acknowledgement of new technology, or to correct possible mistakes. Some users may not be aware of those changes, however, because their jurisdiction enforces an earlier version of the code.

This kind of reasoning can put the people who design, approve, install, test, and maintain fire alarm systems at a disadvantage. In many cases, learning about these new changes and applying them to their fire alarm systems would save stakeholders both time and money.

 For example, the code requires voice intelligibility when installing in-building fire emergency voice/alarm communications systems (EVACS) or mass notification systems (MNS). The emphasis on voice intelligibility in the 2010 edition of NFPA 72 could lead a user to assume that during testing one must take appropriate measurements with a suitable test instrument. Indeed, many authorities having jurisdiction (AHJs) and installers believe that they must measure intelligibility in order to gain acceptance of any emergency communication system.

But the technical committee never intended to require these measurements. Rather, it only intended to assure the systems would meet the performance requirement so that the occupants would understand the voice messages. The 2013 edition of NFPA 72 addresses this specific issue in paragraph 18.4.10.4: “Intelligibility shall not be required to be determined through quantitative measurements” (emphasis added). Chapter 18 goes on to clarify that the quantitative measurements outlined in Annex D.2.4 “shall be permitted but are not required.”

A misunderstanding of this issue could jeopardize the timely acceptance of an emergency communication system and hold back the issuance of an occupancy permit for the building, as well as increase the costs for the project.

Another example of a code change that primarily affects designers and AHJs stems from the new concept, introduced in the 2010 edition of NFPA 72, regarding an “acoustically distinguishable space,” or ADS. The code defines this as an “emergency communications system notification zone, or subdivision thereof, that might be an enclosed or otherwise physically defined space, or that might be distinguished from other spaces because of different acoustical, environmental, or use characteristics, such as reverberation time and ambient sound pressure level.”

The code requires the system designer to determine the ADSs during the planning and design of all emergency communications systems, and in some cases the AHJ must review and approve the details regarding the assignment of ADSs. Even though the code requires the identification of each ADS that would not have voice intelligibility, it leaves open for discussion which spaces a designer should include in that category.

In contrast, the 2013 edition of NFPA 72 specifically states that, unless other governing laws, codes, standards, or other parts of the code require intelligibility, all ADSs do not necessarily require intelligibility. As stated in Annex D, “in some spaces it might be impractical to achieve intelligibility, and in such a case alternatives to voice evacuation might be required within such areas.”

Annex A provides a list of locations that may not require intelligibility, such as private bathrooms, saunas, and similar rooms/areas; mechanical and electrical rooms, storage rooms, and similar rooms/areas; and individual offices, kitchens, and rooms/areas where intelligibility cannot be reasonably predicted.

In short, the 2013 edition of NFPA 72 provides additional guidance and clarity on the ADS issue compared to the 2010 edition, and offers a good illustration of the importance of keeping up with changes to the code. Even if you think you know the code requirements in your jurisdiction, you must always check the most recent edition to ensure you understand every requirement that might affect a particular system installation.

Wayne D. Moore, P.E., FSFPE, is vice president at Hughes Associates.