Gas water heater bonding

Discussion in 'Electrical Forum discussion & Blog' started by ankhseeker, Jan 8, 2014.

  1. ankhseeker

    ankhseeker Member

    Messages:
    80
    Location:
    California
    I recently had a Pv solar system installed for electricity only. The county inspector (in calif) told the installer that the inlet and outlet water pipes of the natural gas water heater had to be tied together. I know that the cold already was grounded. I know that there is potential for electrolysis, but can't figure out why this is code? Any ideas?

    Thanks!
    Last edited: Jan 8, 2014
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,038
    Location:
    Cave Creek, Arizona
    I do it anytime a customer has a problem with frequent water heater failures. It is NOT for electrolysis, it is to give a path for "stray electrical currents" to travel to ground without using the heater tank as a "high retistance" barrier causing corrosion and failure of the tank.
  3. houptee

    houptee Member

    Messages:
    186
    Location:
    Monmouth County, NJ
    If the water heater, or the cold pipe, was ever removed for service or replacement, and a hot pipe was accidentally energized, it would still have a path to ground and hopefully trip the breaker before someone was electrocuted.
    If your piping is copper then all the pipes in the house must be bonded to the grounding electrode.
    Since the cold is already bonded to ground you just have to put grounding clamps on the pipes and a piece of properly sized wire to each clamp to maintain the grounding path.
    Same with a swimming pool, all the metal parts in the pool must be bonded to ground, ladders, lights, diving boards.
  4. ActionDave

    ActionDave Electrician

    Messages:
    361
    Location:
    Colorado
    There is no need to tie the hot and cold water pipes together code or safety wise. It is already done by nature of the construction of the plumbing system.

    The reason swimming pools have all their metal parts bonded together has nothing to do with clearing a fault. The bonding done at a pool does not even have to tie back to the panel the way an equipment ground does. It is to keep people from being shocked by stray currents that move through the earth due to the nature of our electrical power grid.
  5. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,559
    Location:
    North Carolina
    The inspector needs some continuing education. There is no requirement to bond at the water heater
  6. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,443
    Location:
    Houston, TX
    Nothing would surprise me in California.

    The new electrical system should not be using the Pipes for bonding. Not a good Idea just to save wire.

    The bond should be at the breaker panel, and not depend on the water tank or its piping.

    The pipes should be grounded, but should not be used by anything else to obtain one.


    Does that mess make any sense ?
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,038
    Location:
    Cave Creek, Arizona
    THe issue I am referring to has NOTHING to do with "bonding" or "energized hot water lines". The currents I am referring to cannot even be detected by common instruments. I do not know where they come from or if they are even AC currents, but I have had customers who had heaters fail "early", (in a couple of cases withing a year), but after connecting the hot and cold together before the heater, have never had the problem again. Other plumbers who I have told to do this have also found it cures the problem. It used to be a big problem when the telephone company put a ground clamp on a water line and it was the hot water pipe.
  8. ankhseeker

    ankhseeker Member

    Messages:
    80
    Location:
    California
    ok Hj, That makes more sense, but I will take the fall on that one for using the term "bonding" As I remember it, bonding is used to tie a neutral to the ground at the service panel. The inspector stated that there should be a wire between the hot and cold hot water heater pipes (Inlet and outlet ports). Thanks for the tip. I hadn't heard of that before.
  9. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,443
    Location:
    Houston, TX

    The Dish Installers do the same thing.

    But it is against code to use the pipe for grounding.

    Your water pipes are the last place that you want a lightning strike dissipated.

    Sounds like Solar System Installers may be doing the same thing.


    Recharging batteries near a gas water heater can ruin your day.
  10. houptee

    houptee Member

    Messages:
    186
    Location:
    Monmouth County, NJ
    The electrician who did my 4 socket meter pan, and 4 panel upgrades, in 2001 put jumpers across the hot and cold pipes at the 3 water heaters (its a multi family house). And he drove 2 new ground rods and tied ground from meter pan to them, and also left the original ground wire to the cold water pipe coming up from the dirt in the crawlspace, and jumped across the water meter in the meter box out by the curb. He said he had to or it would never pass inspection.

    After Hurricane Sandy my mothers house panel was half submerged so we replaced it, and the chief inspector came to check it out and said you have to add a jumper in the water meter box and across the water heater pipes. I showed him I had driven two new rods 8 ft apart and he said I want you to also bond to the cold pipe where it comes up under the house.
  11. houptee

    houptee Member

    Messages:
    186
    Location:
    Monmouth County, NJ
  12. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,559
    Location:
    North Carolina
    Ask both the inspector and the electrician to give you a code reference that requires the bonding of the hot and cold and post it here please.

    I can tell you that there isn't one to be found.
  13. houptee

    houptee Member

    Messages:
    186
    Location:
    Monmouth County, NJ
    Maybe they are referencing this?

    Section 250.104(A) requires all water-piping systems to be bonded back to the service, and hot or cold water lines are not specifically mentioned, both hot and cold water lines must be bonded and connected back to the building service. The bonding jumper from the cold to the hot water piping system must be sized in accordance with Section and Table 250.66.

    http://www.ecmag.com/section/residential/bonding-hot-water-piping-system
  14. Homeownerinburb

    Homeownerinburb New Member

    Messages:
    525
    Location:
    Los Angeles, CA USA
    Good call on that one. While I was lurking on this thread, I was thinking that the hot and cold were coupled by the various mixing valves in the residence, but now I see that I cannot assume that.

    Seriously, a pair of clamps and a short scrap of the correct cable costs less than the time it takes to install it, and the time is brief as well.

    Now, is it necessary to bond the gas line somewhere? At the water heater would certainly be the place to get this done.
  15. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,559
    Location:
    North Carolina
    Here is the code section in question in its fullest contenet.

    250.104 Bonding of Piping Systems and Exposed Structural Steel.
    (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), (B), and (E). The points of attachment of the bonding jumper(s) shall be accessible.
    (1) General. Metal water piping system(s) installed in or attached to a building or structure shall be bonded to the service equipment enclosure, the grounded conductor at the service, the grounding electrode conductor where of sufficient size, or to the one or more grounding electrodes used. The bonding jumper(s) shall be sized in accordance with Table 250.66 except as permitted in 250.104(A)(2) and (A)(3

    Some will try to call the hot one system and the cold another system so what does the plumbing code say about the water system? First just what is the water called that is used from a water heater?
    501.2 Water heater as space heater. Where a combination potable water heating and space heating system requires water for space heating at temperatures higher than 140°F (60°C), a master thermostatic mixing valve complying with ASSE 1017 shall be provided to limit the water supplied to the potable hot water distribution system to a temperature of 140°F (60°C) or less. The potability of the water shall be maintained throughout the system.

    Was that potable hot water? Well pray tell me just what kind of water must I take a bath with? Now let’s remember that I use hot and cold when showering. What about my kitchen sink?
    602.2 Potable water required. Only potable water shall be supplied to plumbing fixtures that provide water for drinking, bathing or culinary purposes, or for the processing of food, medical or pharmaceutical products. Unless otherwise provided in this code, potable water shall be supplied to all plumbing fixtures.

    I declare I think that the water systems in our homes that we use to flush our toilets is potable water even if we use hot water to get the job done.

    Now where does it say in 250.104(A)(1) that a bonding jumper has to be installed between the hot and cold pipes? That is right it doesn’t, but what it does say is that if one decides to bond the cold and then bond the hot there is only four places that the code allows for this bonding jumper to land, 1) shall be bonded to the service equipment enclosure, 2) the grounded conductor at the service, 3) the grounding electrode conductor where of sufficient size, 4) or to the one or more grounding electrodes used.

    Come to my jurisdiction trying that non code compliant such as is being discussed in this thread and I promise you will be making some changes based on the code sections I have posted.
  16. bluebinky

    bluebinky Member

    Messages:
    408
    Location:
    Santa Clara, CA
    I don't have the exact references handy, so from memory...

    - All metal piping (that might become accidentally energized) must be bonded. So, if you can out argue the AHJ, then it is not required :cool:
    - Fixtures do not count as electrically bonding hot and cold supplies together (at least partially because they can be disconnected during service).
    - A water heater could count, but does not because it can be disconnected for service.
    - Bonding hot and cold at the water heater is a "tradition", at least in many locales.
    - I believe I've seen somewhere that a gas furnace connection to a gas line might meet the bonding requirement, as long as the branch circuit grounding conductor was large enough...
    - Metal piping going into the ground on the inlet side of a gas meter must not be bonded.

    I agree with HJ, that safety is not the only reason for bonding hot & cold...
    Last edited: Jan 10, 2014
  17. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,559
    Location:
    North Carolina
    As a code enforcement official I MUST have the exact code section to enforce anything. There is no code reference to enforce the bonding of the hot to cold and as I pointed out in my last post to do so violates 250.104(A)(1)

    I am the code enforcement official in the city that I work and will turn you down using 250.104(A)(1) every time I see the hot bonded to the cold
    So the bond you install is welded in place so it can’t be removed?
    So replacing a water heater means that the bonding jumper would not be removed in the process?
    Tradition is not enforceable but the code is what is enforced. If tradition is a violation of the adopted electrical code then tradition will be turned down on any job that I inspect.
    I am not allowed to turn down or pass a job based on what I believe I have saw somewhere I must use code references. The equipment grounding conductor can be used to bond gas, Potable, waste, gray, or even air lines when the metal piping system is not a complete metal system as outlined in 250.104(B)
    Yes it can, just can’t use the gas line as an electrode.

    Safety of persons and equipment is the only reason to bond or comply with any code section. The NEC is a minimum safety standard and to do anything less than what it requires is a safety issue. 250.104(A)(1) is very clear where a metal water pipe bonding jumper is to land and hot to cold is not found there therefore to do so is a safety issue.

    Give it a little thought, the plumber uses copper to stub down from the plumbing fixtures but then installs non-metallic pipes between these stubs. Are those stubs required to be bonded together? No. then how does a water heater somehow mandate this bond? It doesn’t. As you pointed out it is just tradition from years gone by. Back before the introduction of non-metallic plumbing pipes there was a requirement in the NEC (1971 and early cycles) to make and keep metal piping systems electrically continuous but with the introduction of non-metallic piping systems this was removed from the NEC as the NEC does not mandate the installation of piping systems. This tradition is a holdover from those days simply because electricians are too lazy to study the book that mandates the installation of systems. They prefer to look at pictures published in some magazine and make their installations look like the picture. As the inspector on the job I must use the NEC for enforcement and am not allowed to use pictures I find including those found in the NEC Handbook.
  18. Reach4

    Reach4 Well-Known Member

    Messages:
    2,648
    Location:
    IL
    I am not familiar with plumbing code. However the use of the word The would seem to me to imply they are referring to the required bonding. To interpret that no other conductors, not being used for the bonding requirement, can pass between two pipes seems surprising, and I would think if that was the intention of the code, they would have said so explicitly.

    I am confident that you would not have a problem with a conductive copper pipe bypass valve across the water heater, yet that would also connect the lines electrically. The water heater itself will normally connect these electrically. So can you think of any reason why the code writers would have intended your interpretation?

    To say that no wires can be added, in addition to those required by code, to solve a galvanic corrosion or a radio frequency interference problem seems oppressive.
  19. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,559
    Location:
    North Carolina
    Galvanic corrosion is the result of two dissimilar metals coming into contact with each other with a DC current applied. Where is this taking place with the water heater? If you say in the connections to the water heater then I will say that the brass union that would be used would make for continuity.
    If you say that flex is being used to connect to the water heater I am going to say that the flex will do either one of two things. One it will maintain continuity or two it will not. If the flex maintains continuity then why do anything more? If the flexible connection is not metallic then where are the different metals coming from?

    You are correct that the word THE means the metal water piping and the word the is singular meaning the water pipe not those water pipes. Is it possible to have more than one metal water piping systems in a house? Yes, there is the potable water system, waste water system, gray water system, and let’s not leave out irrigation which could be part of the potable or gray water systems. I have even saw metal water piping systems installed for heat. Each of these metal water piping systems will require that THE bonding conductor is installed.

    Instead of reading articles in magazines and looking at the picture they have there I go straight to the horse’s mouth when I am doing research on these debatable subjects. Here is a proposal that has the panel statement on it, yes the code making panel charged with voting on the proposals or one could say the words of those charged with writing the code. What is something that any electrician can do to see if a metal piping system of any type is made completely from metal? Would a continuity test do the job?

    5-236 Log #2432 NEC-P05 Final Action: Reject
    (250.104(A)(1))
    ____________________________________________________________
    Submitter: Robert P. McGann, City of Cambridge
    Recommendation: Revise text to read as follows:
    Metal water piping system(s) that is likely to be energized, installed in or attached to a building or structure shall be bonded.
    Substantiation: With much expanded use of plastic water piping system(s) isolating section of metal piping systems. This type of installation leaves contractors and inspectors what is required to be bonded.
    Panel Meeting Action: Reject
    Panel Statement: The requirements of 250.104(A) apply to complete metallic water piping systems. Where there is no complete metallic water piping system, then the requirements of 250.104(B) would apply for those portions of isolated metal water piping system likely to become energized.
    Number Eligible to Vote: 15
    Ballot Results: Affirmative: 15

    See page 220 on this link.
    http://www.nfpa.org/assets/files/AboutTheCodes/70/NEC2008ROP.pdf

    Now you can see that it is not only my opinion but the opinion of those who write the codes that the bonding of hot to cold is not required by the NEC but any bonding jumper installed is required to land at one or the other places outlined in 250.104(A)(1) even if the claim of galvanic corrosion is the purpose of the bond.
  20. bluebinky

    bluebinky Member

    Messages:
    408
    Location:
    Santa Clara, CA
    I just re-read NEC 250.10x in its entirety. All metallic piping/conduits/raceways must be bonded, unless "unlikely" to become energized. In my limited experience "likely" always wins over "unlikely". I do not yet see bonding being "forbidden" anywhere in the code nor JW's quotes.

    As for bonding jumpers ... hmm. 250.98 and 250.98 mention "electrically continuous" and 250.96.98 and 250.64E mention jumpers. 250.64E mentions "at both ends" of a raceway. So far, I see nothing about bonding jumpers with respect to water piping (like I said, I believe it is tradition, except in Maine). JW, are you saying jumpers are OK for say maintaining a continuous EGC when using EMT around a plastic box, but not OK for making supply plumbing electrically continuous for bonding (safety)? If so, I could not out argue that using the NEC...

    On my latest remodel, I ran a #6 from the panel ground to the gas water heater cold inlet continuing on to the hot side without splice. This is in addition to the required grounding electrodes. JW, would you veto that?

    250.104B covers the case of bonding the gas piping to the EGC of the gas furnace circuit.

    A gas water heater and/or plumbing fixture can be replaced without an electrical permit. Removing a hot to cold bonding jumper would be outside the scope of work, and thus illegal...

    Remember the houses that burned in Seattle a while back due to a utility ground fault? Why would anyone want a low impedance connection from an underground gas pipe to the utility neutral...?
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