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Bonding of an NFPA 13 System

Question asked by cox on Aug 4, 2020
Latest reply on Aug 6, 2020 by gytenbeek
  1. The building inspector is requiring an NFPA 13 sprinkler system to be bonded based on the 2017 NEC Section 250.104  Has anyone else run across this?  Here is what both sections state.
    Thank you,

    8.18 Electrical Bonding and Grounding.

    8.18.1 

    In no case shall sprinkler system piping be used for the grounding of electrical systems.

    8.18.2 * 

    The requirement of 8.18.1 shall not preclude the bonding of the sprinkler system piping to the lightning protection grounding system as required by NFPA 780 in those cases where lightning protection is provided for the structure.

    A.8.18.2 

    While the use of the sprinkler system piping as the grounding electrode for the building is prohibited, NFPA 70 requires that all metallic piping systems be bonded to disperse stray electrical currents. Therefore, the sprinkler system piping might be bonded to other metallic systems.

    250.104(A)(1) General.

    Metal water piping system(s) installed in or attached to a building or structure shall be bonded to any of the following:

    1. Service equipment enclosure
    2. Grounded conductor at the service
    3. Grounding electrode conductor if of sufficient size
    4. One or more grounding electrodes used, if the grounding electrode conductor or bonding jumper to the grounding electrode is of sufficient size
      A building inspector is requiring that the NFPA 13 sprinkler system be bonded in accordance with Section NEC 70 Section 250.104 -
      250.104 Bonding of Piping Systems and Exposed Structural Metal.
      250.104(A) Metal Water Piping.

      The metal water piping system shall be bonded as required in (A)(1), (A)(2), or (A)(3) of this section.

    The bonding jumper(s) shall be installed in accordance with 250.64(A), 250.64(B), and 250.64(E). The points of attachment of the bonding jumper(s) shall be accessible. The bonding jumper(s) shall be sized in accordance with Table 250.102(C)(1) except as permitted in 250.104(A)(2) and 250.104(A)(3).

    250.104(A)(2) Buildings of Multiple Occupancy.

    In buildings of multiple occupancy where the metal water piping system(s) installed in or attached to a building or structure for the individual occupancies is metallically isolated from all other occupancies by use of nonmetallic water piping, the metal water piping system(s) for each occupancy shall be permitted to be bonded to the equipment grounding terminal of the switchgear, switchboard, or panelboard enclosure (other than service equipment) supplying that occupancy. The bonding jumper shall be sized in accordance with 250.102(D).

    250.104(A)(3) Multiple Buildings or Structures Supplied by a Feeder(s) or Branch Circuit(s).

    The metal water piping system(s) installed in or attached to a building or structure shall be bonded to any of the following:

    1. Building or structure disconnecting means enclosure where located at the building or structure
    2. Equipment grounding conductor run with the supply conductors
    3. One or more grounding electrodes used

    The bonding jumper(s) shall be sized in accordance with Table 250.102(C)(1), based on the size of the feeder or branch-circuit conductors that supply the building or structure. The bonding jumper shall not be required to be larger than the largest ungrounded feeder or branch-circuit conductor supplying the building or structure.

     

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