George Bernard Shaw said, “The problem with communication ... is the illusion that it has been accomplished.” Shaw’s feelings aside, those in the fire alarm system installation business now find themselves knee-deep in new communications systems installations.
The National Fire Protection Association (NFPA) membership adopted the 2010 edition of NFPA 72, the National Fire Alarm and Signaling Code, in June 2009 with an effective date of Aug. 26, 2009. NFPA 72 2010 supersedes all previous editions. Now, a new chapter covering emergency communications systems (ECS) is available.
Recently, the NFPA and the Automatic Fire Alarm Association have reported numerous jurisdictions have already begun the process of adopting the new code. Normally, jurisdictions wait up to two code-revision cycles after the publication of a particular edition of a code or standard before adopting it for use within those jurisdictions. It would seem, from the buzz surrounding the new code adoption frenzy, that a tremendous interest has developed in the new chapter covering ECS requirements.
Officials in jurisdictions that have already adopted this edition of the code, such as Alabama, California and Massachusetts, have stated the ECS chapter is the main reason for their early adoption. Particularly, the reason is the ECS chapter allows the use of fire alarm system emergency voice alarm communications systems (EVACS) for general paging and background music; and this new chapter also contains the requirements for mass notification systems (MNS).
MNS have already become the norm in all U.S. Defense Department facilities. At those facilities, all fire alarm systems now must have the capability to transmit the sound of a human voice and may serve as a combination fire alarm system and MNS. Many large commercial facilities and college campuses have also begun to upgrade their fire alarm system infrastructure to include MNS in every building. As a result, contractors who have successfully installed fire alarm systems for some time now must learn the requirements and guidelines for sound and communications systems.
Typically, fire alarm and electrical contractors have limited or no background in professional sound and communications. Previous editions of the code stressed the audibility of the audible notification appliances. The code required measurements based on prescriptive values measured against the ambient noise levels of a space. The new code requires the speaker system to meet a performance standard for intelligibility. Specifically, “Within the acoustically distinguishable spaces (ADS) where voice intelligibility is required, voice communications systems shall reproduce prerecorded, synthesized, or live (e.g., microphone, telephone handset, and radio) messages with voice intelligibility.”
This section introduces a new term: “acoustically distinguishable spaces,” defined 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.”
As a contractor, some of the more immediate issues you must learn include how to ensure intelligibility of the messages these new systems produce. The first surprise you will encounter is that you will now install more speakers in your ECS or MNS. Designers and installers should understand the importance of having a healthy distribution of speakers, rather than trying to use a higher power output of a few speakers. For example, for a standard building configuration with normal ceiling height and construction, standard wall configurations and finishes, and carpeted floors, ceiling-mounted speakers should be installed in all normally occupiable spaces and in corridors spaced at a maximum of twice the ceiling height or as determined by a commercially available computer acoustical/-speaker modeling program.
Most contractors know that the tap setting on the connected speaker affects audibility and intelligibility. The speaker system must meet the audibility requirements of the code, while still having the message intelligible. Some believe that they may increase the tap setting to make the signal loud enough, although doing so could distort the intelligibility.
Contractors must give special attention to acoustically challenging ADS. Such areas might incorporate hard surfaces or high ceilings, which will require more stringent designs to ensure intelligibility.
To learn more about the correct way to install ECS, consult the NFPA 72 2010 “National Fire Alarm and Signaling Code Handbook.” You will find another source for design guidance in the NEMA Standards Publication: SB 50-2008, Emergency Communications Audio Intelligibility Applications Guide.
As a contractor, you can prepare for the new requirements by developing an understanding of basic communications systems principles. Only then will your installations truly meet the needs of your customers and satisfy the new code requirements.
MOORE, a licensed fire protection engineer, frequent speaker and an expert in the life safety field, is a past chair of the NFPA 72 Technical Correlating Committee. Moore is a principal with Hughes Associates Inc. at the Warwick, R.I., office. He can be reached at email@example.com.