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  1. #1
    Join Date
    Mar 2007
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    Cape Cod, Massachusetts
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    583

    Default Bonding of metal piping systems

    Why don't we see bonding of hydronic heat distribution system metal piping? Why is it not required?
    also, why isn't Metal vent pipe or metal chimney pipe required to be bonded. It seems like these systems could likely become energized if not bonded to the service equipment enclosure??

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    Inspection Referral SOC
    Ken Amelin
    Cape Cod's Best Inspection Services
    www.midcapehomeinspection.com

  2. #2
    Join Date
    Mar 2007
    Location
    Santa Rosa, CA
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    2,617

    Default Re: Bonding of metal piping systems

    Quote Originally Posted by Ken Amelin View Post
    Why don't we see bonding of hydronic heat distribution system metal piping? Why is it not required?
    also, why isn't Metal vent pipe or metal chimney pipe required to be bonded. It seems like these systems could likely become energized if not bonded to the service equipment enclosure??
    Ken,

    Article 100 (definitions)
    Grounding Conductor, Equipment (EGC). The conductive path( ) installed to connect normally non*current-carrying metal parts of equipment together and to the system grounded conductor or to the grounding electrode conductor, or both.
    Informational Note No.1: It is recognized that the equipment grounding conductor also performs bonding.

    I think the above is what you are looking for.

    Systems can be bonded by the EGC that is likely to energize the system. So, metal piping in the hydronic system is likely to be energized by the pump, but the pump is bonded with the EGC. Same could be said for metal ducting. Not sure about metal sewer drain piping.

    Chimneys might be energized by a lightning strike, but I believe there is a different NFPA publication that deals with that.

    Department of Redundancy Department
    http://www.FullCircleInspect.com/

  3. #3
    Join Date
    Mar 2007
    Location
    Cape Cod, Massachusetts
    Posts
    583

    Default Re: Bonding of metal piping systems

    Quote Originally Posted by Gunnar Alquist View Post
    Ken,

    Article 100 (definitions)
    Grounding Conductor, Equipment (EGC). The conductive path( ) installed to connect normally non*current-carrying metal parts of equipment together and to the system grounded conductor or to the grounding electrode conductor, or both.
    Informational Note No.1: It is recognized that the equipment grounding conductor also performs bonding.

    I think the above is what you are looking for.

    Systems can be bonded by the EGC that is likely to energize the system. So, metal piping in the hydronic system is likely to be energized by the pump, but the pump is bonded with the EGC. Same could be said for metal ducting. Not sure about metal sewer drain piping.

    Chimneys might be energized by a lightning strike, but I believe there is a different NFPA publication that deals with that.
    Thanks Gunnar, That adds a piece to the puzzle, but pumps are isolated with rubber gaskets.

    Ken Amelin
    Cape Cod's Best Inspection Services
    www.midcapehomeinspection.com

  4. #4
    Join Date
    Mar 2007
    Location
    Plano, Texas
    Posts
    4,194

    Default Re: Bonding of metal piping systems

    Bonding IS required but is not uniformly enforced by the local AHJ. My thought is this is not an intentional act but simply oversight by individuals doing the inspections.

    Jim Luttrall
    www.MrInspector.net
    Plano, Texas

  5. #5
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    26,560

    Default Re: Bonding of metal piping systems

    250.104 Bonding of Piping Systems and Exposed Structural Metal.
    - (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.
    - - (1) General. Metal water piping system(s) installed in or attached to a building or stsructure shall be bonded to any of the following:
    (blah, blah, blah)


    That code section does not state "potable water metal water piping systems", it just says "metal water pipings systems".


    A DWV systen is not necessarily a "water piping system" (although I've argued that cast iron drain pipes 'should' (versus 'shall') be bonded as they can also energize plumbing fixtures, but, alas, DWV metal systems are not considered as "water piping systems" for the purposes of this section.


    - (B) Other Metal Piping. If installed in or attached to a building or structure, a metal piping system(s), including gas piping, that is likely to become energized shall be bonded to any of the following:
    - - (1) Equipment grounding conductor for the circuit that is likely to energize the piping system.


    I.e., such as a metal (other than CSS) gas piping system attached to a furnace, water heater, stove, etc, are required to be bonded, and being as the appliance is the circuit "like to energize the piping system", the equipment grounding conductor to that appliance(s) is considered the bond for that metal gas piping.


    Now, take an "other metal piping system" and put water in it ... wait ... that puts it under "metal water piping system" ... except for DWV piping systems ...

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

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