NFPA 72 is evolving rapidly. Are you keeping up?
NFPA Journal®, March/April 2011
Because many states and jurisdictions have already adopted the 2010 edition of NFPA 72®, National Fire Alarm and Signaling Code, it becomes imperative for those of us who work regularly with fire alarm systems to understand the changes, since they affect how new fire alarm systems are designed, installed, and inspected. Keeping up to date is important, since the technical committees have already met to address hundreds of proposals for changes to the 2013 edition of the code. While I can’t cover all of the code changes in this column, I can highlight a few important ones. NFPA offers educational programs, as do the Automatic Fire Alarm Association and other organizations, that review major code changes.
One important change to the code occurs in the new Chapter 12, Circuits and Pathways, where the "Style" designations for fire alarm circuits have disappeared. All designations of circuits are now by Class only and include Class A, Class B, Class C, Class D, Class E, or Class X, depending on the circuit’s performance.
The Annex A material provides some of the background from the technical committee that explains the circuit operating characteristics and performance, as well as the technical committee’s intent.
"In the 2007 edition of NFPA 72, initiating device circuit, signaling line circuit, and notification appliance circuit performance class/style tables were rooted in ‘copper’ wiring methods," the Annex reads. "Fire alarm control units use new communication technologies, such as Ethernet, fiber optics, and wireless, which do not fit in the ‘copper’ wiring methods."
The intent of the circuit designations, according to the Annex, is not to create a hierarchal ranking, but rather to provide guidance on the levels of performance.
"Singular ground-fault conditions that do not affect operation of the pathway are not specifically covered in Chapter 12, but are covered by the requirements of other chapters," the Annex states. "Users of the Chapter 12 designations should review whether there are other abnormal conditions not specified in Chapter 12 that the pathways need to annunciate and operate through for their application."
Class C is a completely new designation, and its performance is described as including "one or more pathways where operational capability is verified via end-to-end communication, but the integrity of individual paths is not monitored."
The importance of Class C is that it is intended to describe technologies "that supervise the communication pathway by polling or continuous communication ‘handshaking’." These technologies include fire control unit or supervisory station connections to a wired or wireless LAN, WAN, or Internet; fire control unit or supervisory station connections to a wireless proprietary communications system; and fire control unit digital alarm communication transmitter or supervisory station digital alarm communication receiver connections to the public switched telephone network.
This is just one example of the way the code has made wholesale changes to the way we used to do things. Anyone who uses NFPA 72 today needs to make a concerted effort to obtain a copy of the new code, or, better yet, attend a seminar to review the changes.
Wayne D. Moore, P.E., FSFPE, is a principal with Hughes Associates.