Monday, February 19, 2018

NFPA 72 2016 Chapter 12 Changes

NFPA 72 2016 Chapter 12 - Circuits and Pathways


The following covers the changes, updates and additions to Pathway Class Designations.  Remember to consult the Annex A when you see an *.

All information highlighted in this light blue color is NEW to the 2016 edition of NFPA 72.

  • 12.2.3.4* Where operational capability is required to be maintained or continued during the application of a fault, the operational capability required in 10.11.1 shall be restored within 200 seconds from the time the fault is introduced.
  • 12.3* Pathway Class Designations. pathways shall be designated as Class A, Class B, Class C, Class E, Class N, or Class X, depending on their performance.
  • 12.3.3* Class C.  A pathway shall be designated as Class C when it performs as follows:
    • (2) A loss of end-to-end communication is annunciated as a trouble signal.
  • 12.3.6 Class N. A pathway shall be designated as class N when it performs as follows:
    • (1)* It includes two or more pathways where operational capability of the primary pathway and a redundant pathway to each device shall be verified through end-to-end communication.  Exception: When only one device is served, only one pathway shall be required.
    • (2) A loss of intended communications between endpoints shall be annunciated as a trouble signal.
    • (3) A single open, ground, short or combination of faults on one pathway shall not affect any other pathway.
    • (4)* Conditions that affect the operation of the primary pathway(s) and redundant pathway(s) shall be annunciated as a trouble signal when the system's minimal operational requirements cannot be met.
    • (5)* Primary and redundant pathway shall not be permitted to share traffic over the same physical segment.
  • 12.3.8* Class A and Class X Pathway Separation.
    • 12.3.8.1 The outgoing and return (redundant) circuit conductors shall be permitted in the same cable assembly (i.e., multi-conductor cable), enclosure, or raceway only under the following conditions:
      • (1) For a distance not to exceed 10 ft. where the outgoing and return conductors enter or exit the initiating device, notification appliances, or control unit enclosures.
      • (2) Single drops installed in the raceway to individual devices or appliances.
      • (3)* In a single room not exceeding 1000 sq' in area, a drop installed in the raceway to multiple devices or appliances that does not include any emergency control function devices.  

The following is a California State amendment.  This only applies if you are conducting work in the state of California:

  • 12.3.8.1 The outgoing and return (redundant) circuit conductors shall be permitted in the same cable assembly (i.e., multi-conductor cable), enclosure, or raceway only under the following conditions:
    • (4) Where the vertically run conductors are contained in a 2-hour rated cable assembly, or enclosed (installed) in a 2-hour rated enclosure or a listed circuit integrity (C.I.) cable, which meets or exceeds a 2-hour fire resistive rating.


NFPA 72 2016 Chapter 14 - Inspection, Testing and Maintenance


NFPA 72 2016 Chapter 10 - Fundamentals