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Thread: Bonding isolated section of Metal water Pipe - 250.104

  1. #1
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    Bonding isolated section of Metal water Pipe - 250.104

    This is an old house plumbed with copper water lines. Inspector came in to inspect upgrade and remodel in one part of the house. He found pre-existing work he has cited. Inspector wants me to bond sections of copper water pipe around a section that was previously repaired with PEX. This section is Upstream from the bonding jumper between the panel and the connection to the cold water pipe. Hot and Cold lines are bonded together thru several substantial brass mixing valves used in the existing plumbing system. Pex was used to repair a leaking section on the cold water line in the basement where it goes up an interior wall to the second floor bath. Upstream of this Pex repair is only this bath. The bath circuit is protected by a GFCI. Mike makes a note in his book "Understanding the NEC" under this section as follows: "Bonding is not required for isolated sections of metal water pipe connected to a non-metallic water piping system". I have researched this code section and can't find much additional info on the exception Mike references. I realize it may be easiest to just install a bonding jumper, properly sized. I am curious about the exception Mike mentioned vs the inspector's interpretation as I am apt to encounter this again in the course of my property management business. Appreciate your insights. Thanks

  2. #2
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    Quote Originally Posted by mcgroh View Post
    This is an old house plumbed with copper water lines. Inspector came in to inspect upgrade and remodel in one part of the house. He found pre-existing work he has cited. Inspector wants me to bond sections of copper water pipe around a section that was previously repaired with PEX. This section is Upstream from the bonding jumper between the panel and the connection to the cold water pipe. Hot and Cold lines are bonded together thru several substantial brass mixing valves used in the existing plumbing system. Pex was used to repair a leaking section on the cold water line in the basement where it goes up an interior wall to the second floor bath. Upstream of this Pex repair is only this bath. The bath circuit is protected by a GFCI. Mike makes a note in his book "Understanding the NEC" under this section as follows: "Bonding is not required for isolated sections of metal water pipe connected to a non-metallic water piping system". I have researched this code section and can't find much additional info on the exception Mike references. I realize it may be easiest to just install a bonding jumper, properly sized. I am curious about the exception Mike mentioned vs the inspector's interpretation as I am apt to encounter this again in the course of my property management business. Appreciate your insights. Thanks

    It sounds like you have a metallic water piping system that has been interrupted by the installation of a piece of Pex. If you read Mike's quote it stating that isolated metallic sections used with a non-metallic piping system do not require bonding. IMO that's not what you have you have a metallic water piping system.
    Rob

    Moderator

    All responses based on the 2014 NEC unless otherwise noted

  3. #3
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    I don't think a group of inspectors would give you the same answer on this one. If it's a metal water system, it is required to be bonded. If it's a metal water faucet on a plastic system it is not required to be bonded. How long is your metal pipe that is not bonded? Is it likely to become energized?
    250.104 (A)

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    Quote Originally Posted by mcgroh View Post
    This is an old house plumbed with copper water lines. Inspector came in to inspect upgrade and remodel in one part of the house. He found pre-existing work he has cited. Inspector wants me to bond sections of copper water pipe around a section that was previously repaired with PEX. This section is Upstream from the bonding jumper between the panel and the connection to the cold water pipe. Hot and Cold lines are bonded together thru several substantial brass mixing valves used in the existing plumbing system. Pex was used to repair a leaking section on the cold water line in the basement where it goes up an interior wall to the second floor bath. Upstream of this Pex repair is only this bath. The bath circuit is protected by a GFCI. Mike makes a note in his book "Understanding the NEC" under this section as follows: "Bonding is not required for isolated sections of metal water pipe connected to a non-metallic water piping system". I have researched this code section and can't find much additional info on the exception Mike references. I realize it may be easiest to just install a bonding jumper, properly sized. I am curious about the exception Mike mentioned vs the inspector's interpretation as I am apt to encounter this again in the course of my property management business. Appreciate your insights. Thanks
    Please explain what you mean by the part in red.

    Are you saying the pex is between where the water pipe enters the building and where the connection to the grounding electrode system is made? if that is what you are saying I think the inspector is correct. Actually I think you would need to move the wire to upstream of the pex and then bond the two sections of pipe.
    Bob

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    I realize you want a code correct answer, however in the time it would have taken me to type what you typed out I could have run a bonding jumper please the inspector gotten the green light and then on to the next job. Run the bonding jumper don't let it hold up your work.
    Electricians do it until it Hertz!

  6. #6
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    I’m inclined to agree that you have a metal piping system, bond and move on.
    Tom
    TBLO

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    Quote Originally Posted by mcgroh View Post
    I am curious about the exception Mike mentioned vs the inspector's interpretation as I am to encounter this again in the course of my property management business. Appreciate your insights. Thanks
    Sounds like you are in a perfect position to facilitate a detail that commonly falls through a hole created by plumbing repairs not being considered as having anything electrical in their description.

    Inserting nonconductive plumbing in an otherwise conductive metallic water piping system needs the electrical bonding repair included with the plumbing repair of an older occupancy. It's really that simple. But I'm not aware of there being a Code citation to mandate it.

    Prior to the 1993 NEC changes, a conductive cold water pipe could be bonded to anywhere in the metallic water piping system to establish a new Equipment Grounding Electrode for electrical repairs, alterations or additions. These bonds were allowed without documentation, and their existence is soon forgotten.
    Another Al in Minnesota

  8. #8
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    Suppose you have a house with an all-copper water supply, but the water main is plastic? Does it matter where the pipe termination is? Is it still required to be sized per the service rating? If a service upgrade is performed, say from 200a to 400a, must a second #4 cu be run, or can the new disco's #4 be spliced onto the existing one the same way the rods' #6 can?
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  9. #9
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    Quote Originally Posted by ptonsparky View Post
    I’m inclined to agree that you have a metal piping system, bond and move on.
    Thanks you all for responding. As I stated in my original question, bond and move on is probably the most efficient response. But to clarify and answer some of the other questions you asked:

    -it is a copper pipe water supply system. This pex repair was made in an isolated section on the cold water side in the basement on the branch that supplies the Second floor bath. The bonding connection to the panel and the cold side of the copper water supply is made further up stream, closer to the water supply entrance. So what this repair did was to isolate a section of the cold water line beyond this repair. The pex, being not conductive, broke the current path so that the cold water line from that point is no longer bonded as originally intended HOWEVER because this only affected the COLD water line and the hot water side is bonded thru the many brass mixing valves in the home. Therefore the cold water side beyond the repair is still bonded thru the "back" connection thru the valves in the second floor bath to the hot side. (I really hope I haven't confused this!).

    -there is little likelihood that this section could become energized and, as I stated, the bath circuit is protected by a GFCI.

    - Your point about this NOT being a non-metallic water piping system is key. I hadn't considered this as I obviously, being human, was looking for an answer which confirmed my beliefs! ;>)

    -My secondary question was to find the code section or exception that describes the exception Mike mentions in his book, the exception which excludes bonding of isolated sections of metallic pipe in a non-metalic piping system. I could find no mention of that in this code section (250.104) or elsewhere. If someone could find that and reference I'd appreciate it for my own edification.

    So I am going to install a jumper, thank the inspector for his vigilance and move on, thankful that I may still win the war even having just lost a minor skirmish!

    Thanks!

  10. #10
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    Quote Originally Posted by al hildenbrand View Post
    Sounds like you are in a perfect position to facilitate a detail that commonly falls through a hole created by plumbing repairs not being considered as having anything electrical in their description.

    Inserting nonconductive plumbing in an otherwise conductive metallic water piping system needs the electrical bonding repair included with the plumbing repair of an older occupancy. It's really that simple. But I'm not aware of there being a Code citation to mandate it.

    Prior to the 1993 NEC changes, a conductive cold water pipe could be bonded to anywhere in the metallic water piping system to establish a new Equipment Grounding Electrode for electrical repairs, alterations or additions. These bonds were allowed without documentation, and their existence is soon forgotten.
    This is exactly what the inspector said! He placed the blame on the plumber!

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