No More Styles for Fire Alarm Circuits

NFPA 72 2010, the National Fire Alarm and Signaling Code has three new chapters.  One of these new chapters is dedicated to circuits and pathways.

Business owners and installers involved with the fire alarm installation industry will know that since 1993, we have had to deal with both classes and styles of circuits.

Newer fire alarm panels and systems are now utilizing more efficient methods of communication technologies, such as Ethernet, fiber optic and wireless.  These methods do not exactaly fall into the previous version of the codes basis for copper wiring methods in initiating device circuits, signaling line circuits and notification appliance circuits.

The new NFPA 72 NFPA 72: National Fire Alarm and Signaling Code Handbook (2010) has eliminated the circuit styles.  Instead, NFPA now designates circuits and pathways as Class A, Class B, Class C, Class D, Class E or Class X, depending on their performance.

It is understood that it is not the intent of the code's circuit designation to provide a hierarchal ranking, but rather provide guidance on the levels of performance.  If you are still confused, NFPA 72 2010 has the initiating device circuit, signaling line circuit and notification appliance circuit class/style tables from previous editions in the Annex A.

Below is how NFPA 72 2010 now designates the performance of each circuit pathway.

CLASS A:  Pathway includes a redundant path.  The pathway's operational capability continues past a single open fault.  The fire alarm control panel (FACP) annunciates any condition that affect the intended operation of the path.

CLASS B:  Pathway does not include a redundant path.  Its operational capability stops at a single open.  The fire alarm control panel (FACP) annunciates any conditions that affect the intended operation of the path.

CLASS C:  Pathway includes one or more paths where end-to-end communications verifies the operational capability of the total pathway.  The fire alarm control panel (FACP) does not monitor the integrity of individual paths.  The FACP does annunciate a loss of end-to-end communication.  Make sure to note that Class C reference is new and is intended to describe technologies that monitor the integrity of the communication pathway by polling or continuous communication "handshaking."  Examples of Class C pathways could include the following: (1) FACP or supervisory station connections to a wired LAN, WAN or internet.  (2) FACP or supervisory station connections to a wireless LAN, WAN or internet.  (3)  FACP or supervisory station connections to a wireless proprietary communications and (4) FACP digital alarm communicator transmitter (DACT) or supervisory station digital alarm communication receiver connections to the public switched telephone network.

CLASS D:  Pathway provides fail safe operation.  The FACP does not annunciate faults.  The pathway does perform the intended operation in the event of a pathway failure.  Examples of Class D circuits would include circuits that provide power to door holders, where interruption of the power results in the door closing.  They may also include circuits that provide power to locking hardware that release upon an open circuit or contact operation within the FACP.

CLASS E:  Is a pathway where the FACP does not need to monitor the integrity of the pathway, as described in Section 10.17 of NFPA 72 2010.

CLASS X:  Pathway includes a redundant path.  Its operational capability continues past a single open or short circuit.  The FACP annunciates conditions that affect the intended operation of the path.  This new designation intends to apply to SLC pathways as described in the previous versions of the code as "style 7."

NFPA 72 2010 also requires that the installation of a circuits and pathways are installed in accordance with NFPA 70 the National Electrical Code NEC 2011 edition.  National Electrical Code 2011 Handbook (National Fire Protection Association//National Electrical Code Handbook)

Fiber optic cables installed as part of the fire alarm system must meet the requirements of NEC Article 770.  Per NEC Article 760 the fiber optic cables must be installed using a method to protect the cables from physical damage.  Fiber Optic Installer's Field Manual (First-Choice Field Manuals)

Please make sure you know what version of the code your local fire jurisdiction is currently enforcing as these new codes might not in effect.