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  1. #1

    Default gas line bonding

    I know the gas line to a gas furnace or gas stove that is properly grounded is considered bonded.
    What about the same gas line that supplies the standard gas water heater, is it also bonded due to the furnace, stove, gas dryer etc being on a grounded circuit? I know this is nit picky but if you have to bond the water line to the water heater why not the gas line also?

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    Default Re: gas line bonding

    Quote Originally Posted by Don Hawley View Post
    I know the gas line to a gas furnace or gas stove that is properly grounded is considered bonded.
    What about the same gas line that supplies the standard gas water heater, is it also bonded due to the furnace, stove, gas dryer etc being on a grounded circuit? I know this is nit picky but if you have to bond the water line to the water heater why not the gas line also?
    Don,

    From the 2011 NEC (I had that handy, but it's pretty much the same in later editions)

    250.104
    (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 the service equipment enclosure; the grounded conductor at the service; the grounding electrode conductor, if of sufficient size; or to one or more grounding electrodes used. The bonding conductor(s) or jumper(s) shall be sized in accordance with 250.122, using the rating of the circuit that is likely to energize the piping system(s). The equipment grounding conductor for the circuit that is likely to energize the piping shall be permitted to serve as the bonding means. The points of attachment of the bonding jumper(s) shall be accessible.


    The clue is the second to last sentence. Since gas-fired forced air furnaces (blowers) are generally powered by 120 volts, theirs is the "circuit that is likely to energize the piping". Most gas-fired water heaters do not have 120 or 240 volts, so they are not "likely to energize the piping".

    However, now that you bring this up, some of the newer high-efficiency water heaters do use 120 volts to power the forced-draft blower.

    Does this help?

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  3. #3

    Default Re: gas line bonding

    Quote Originally Posted by Gunnar Alquist View Post
    Don,

    From the 2011 NEC (I had that handy, but it's pretty much the same in later editions)

    250.104
    (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 the service equipment enclosure; the grounded conductor at the service; the grounding electrode conductor, if of sufficient size; or to one or more grounding electrodes used. The bonding conductor(s) or jumper(s) shall be sized in accordance with 250.122, using the rating of the circuit that is likely to energize the piping system(s). The equipment grounding conductor for the circuit that is likely to energize the piping shall be permitted to serve as the bonding means. The points of attachment of the bonding jumper(s) shall be accessible.


    The clue is the second to last sentence. Since gas-fired forced air furnaces (blowers) are generally powered by 120 volts, theirs is the "circuit that is likely to energize the piping". Most gas-fired water heaters do not have 120 or 240 volts, so they are not "likely to energize the piping".

    However, now that you bring this up, some of the newer high-efficiency water heaters do use 120 volts to power the forced-draft blower.

    Does this help?
    Thanks Gunner, but you just restated what I said I understood. Had a spirited discussion with a seller's electrician over whether the standard water heater gas line needed to be bonded since the furnace was connected by 12-2 w/g. His point was the gas lines were all connected. Copper water lines were bonded and this could have been fixed with two clamps and 12 inches of wire. Was i wrong to call for bonding of the water heater gas line.


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    Default Re: gas line bonding

    Quote Originally Posted by Don Hawley View Post
    Thanks Gunner, but you just restated what I said I understood. Had a spirited discussion with a seller's electrician over whether the standard water heater gas line needed to be bonded since the furnace was connected by 12-2 w/g. His point was the gas lines were all connected. Copper water lines were bonded and this could have been fixed with two clamps and 12 inches of wire. Was i wrong to call for bonding of the water heater gas line.
    Hi Don,

    Sorry, I apparently misunderstood your question.

    I have a difficult time with bonding myself. There are a few things that I don't entirely understand about it. For example around here, the gas line is now (maybe for the past 6 or 7 years) always bonded at the meter with a bonding clamp similar to the type found on the water supply line. However, as discussed, the code says that it can be bonded with the heater grounding conductor. So why are my local building departments requiring the independent bonding? I haven't asked yet.

    As far as bonding the gas piping goes, one place should be fine, whether at the heater, water heater or meter. As you said, the piping is interconnected. Black pipe will have greater resistance than copper, so there is a possibility of a difference in potential voltage at various points along the piping, but in a residence it should not be significant.

    My understanding about bonding the hot and cold at the water heater is to ensure both the hot and cold pipes are always bonded. If a water heater is removed, the piping should remain bonded, to prevent any difference in voltage between the two pipes (might shock the plumber replacing the tank). In my area, the water heater is not going to provide the bond between hot and cold because dielectric fittings are typically used at the water supply connections. Therefore, the jumper above the water heater is required. I would expect that brass plumbing fixtures (shower & tub) would provide a positive connection between hot and cold water pipes, but, again, in my area, the AHJ requires the bonding jumper above the water heater. It might just be redundant, it might be to ensure bonding without relying on a mixing valve or it might be that some plumbing fixtures are coming out with nonconductive materials. Not sure there.

    Back to gas piping... Currently, CSST must be bonded with a #6 conductor. I am guessing here, but my local AHJs might be figuring that CSST is going to be installed at some time in the future and they want to make sure that it is bonded, even if an adventurous homeowner does it. As we all know, homeowners rarely let a lack of knowledge stop them from making modifications to their homes. As a result, I feel that bonding with a #6 is the better choice.

    Hopefully, Jerry Peck will chime in soon to tell me why I am wrong and what I missed.

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    Default Re: gas line bonding

    Let's start with bonding piping systems.

    from the 2017 NEC:

    - 250.104 Bonding of Piping Systems and Exposed Structural Metal.
    - - (A) Metal Water Piping. (a different discussion)
    - - (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
    - - - (2) Service equipment enclosure
    - - - (3) Grounded conductor at the service
    - - - (4) Grounding electrode conductor, if of sufficient size
    - - - (5) One or more grounding electrodes used
    - - - The bonding conductor(s) or jumper(s) shall be sized in accordance with 250.122, using the rating of the circuit that is likely to energize the piping system(s). The points of attachment of the bonding jumper(s) shall be accessible.

    And

    - 110.3 Examination, Identification, Installation, and Use of Equipment
    - - (B) Installation and Use. Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling.

    110.3(B) says "shall be installed and used in accordance with" the manufacturer's installation instructions (because those are part of the listing or labeling). And CSST manufacturers require addition bonding.

    Back to the original question:

    Quote Originally Posted by Don Hawley View Post
    Had a spirited discussion with a seller's electrician over whether the standard water heater gas line needed to be bonded since the furnace was connected by 12-2 w/g. His point was the gas lines were all connected. Copper water lines were bonded and this could have been fixed with two clamps and 12 inches of wire. Was i wrong to call for bonding of the water heater gas line.
    His point was that it "was not required", and your point was "but it is cheap and easy enough to do" ... both of which are valid and correct.

    Is there any reason not to bond the gas piping to the already bonded interior metal water piping at the gas fired water heater with no electric equipment on it?

    Yes, there is one reason.

    "It is not required."

    Is there any harm in bonding the gas piping to the already bonded interior metal water piping at the gas fired water heater with no electric equipment on it?

    Nope.

    Jerry Peck, Construction / Litigation Consultant
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    Default Re: gas line bonding

    Quote Originally Posted by Gunnar Alquist View Post
    Don,

    From the 2011 NEC (I had that handy, but it's pretty much the same in later editions)

    250.104
    (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 the service equipment enclosure; the grounded conductor at the service; the grounding electrode conductor, if of sufficient size; or to one or more grounding electrodes used. The bonding conductor(s) or jumper(s) shall be sized in accordance with 250.122, using the rating of the circuit that is likely to energize the piping system(s). The equipment grounding conductor for the circuit that is likely to energize the piping shall be permitted to serve as the bonding means. The points of attachment of the bonding jumper(s) shall be accessible.


    The clue is the second to last sentence. Since gas-fired forced air furnaces (blowers) are generally powered by 120 volts, theirs is the "circuit that is likely to energize the piping". Most gas-fired water heaters do not have 120 or 240 volts, so they are not "likely to energize the piping".

    However, now that you bring this up, some of the newer high-efficiency water heaters do use 120 volts to power the forced-draft blower.

    Does this help?
    We have to jump the hot / cold and gas of a water heater with a #8 in my city

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    Default Re: gas line bonding

    Quote Originally Posted by Marc M View Post
    We have to jump the hot / cold and gas of a water heater with a #8 in my city
    Marc,

    #8, not #6? Interesting. I believe I have only seen #6 around here. What city? I wouldn't have to ask if you had it in your profile like I do.

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    Default Re: gas line bonding

    I believe the Mechanical code wants the incoming gas line bonded . (I will be researching this)
    I see it being done on houses all the time .
    They run a #4 bare copper from the electrical panel ground bar to the incoming gas line. They are connecting it ahead of the meter.
    I have had spirited conversations with some people about this. As it is creating a violation of the NEC, as the NEC says one can not use the incoming metallic gas piping as an grounding electrode.


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    Default Re: gas line bonding

    Quote Originally Posted by jack davenport View Post
    I have had spirited conversations with some people about this. As it is creating a violation of the NEC, as the NEC says one can not use the incoming metallic gas piping as an grounding electrode.
    And they aren't using the gas line as a grounding electrode, they are simply bonding the gas line to the grounding system.

    Think of it this way: Interior metal water piping and underground metal water piping

    Interior metal water piping is bonded to the grounding system while the underground metal water piping is being used as a grounding electrode, and the location of the grounding electrode conductor to the underground metal water piping must be within 5 feet of the entrance of the underground metal water piping into the structure (not the exact wording, but that's basically what it says), however, if there is interior metal water piping only, the location of the bonding conductor no longer has to be at that within 5 feet point, and, if the exterior underground metal water piping is replaced with PVC ... and replaced all the way into the building for (let's just say) 10 feet, what was the grounding electrode conductor now becomes a bonding jumper, and (naturally) cannot be, nor needs to be, within that 5 feet of the entrance. (Whew! That was a long run-on sentence!)

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    Default Re: gas line bonding

    Quote Originally Posted by Gunnar Alquist View Post
    Marc,

    #8, not #6? Interesting. I believe I have only seen #6 around here. What city? I wouldn't have to ask if you had it in your profile like I do.
    Im in Santa Clarita. just installed a water heater and it was what was required

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    Default Re: gas line bonding

    Bonding and connection to the Grounding electrode are similar in look and function, really only different in intent.
    The intent of the code is to provide a Grounding electrode to communicate/dissipate to the ground. The gas line cannot be used for the purpose of a Grounding Electrode, you must provide some other GE such as water line, UFER, plate, ring, or rod. Once the Grounding electrode system is in place then EVERYTHING must be bonded to that system which is why the gas pipe system IS connected to the Grounding electrode as part of the required bonding.

    Jim Luttrall
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    Default Re: gas line bonding

    Quote Originally Posted by jack davenport View Post
    I believe the Mechanical code wants the incoming gas line bonded . (I will be researching this)
    I see it being done on houses all the time .
    They run a #4 bare copper from the electrical panel ground bar to the incoming gas line. They are connecting it ahead of the meter.
    I have had spirited conversations with some people about this. As it is creating a violation of the NEC, as the NEC says one can not use the incoming metallic gas piping as an grounding electrode.
    Quote Originally Posted by Jerry Peck View Post
    And they aren't using the gas line as a grounding electrode, they are simply bonding the gas line to the grounding system.

    Think of it this way: Interior metal water piping and underground metal water piping

    Interior metal water piping is bonded to the grounding system while the underground metal water piping is being used as a grounding electrode, and the location of the grounding electrode conductor to the underground metal water piping must be within 5 feet of the entrance of the underground metal water piping into the structure (not the exact wording, but that's basically what it says), however, if there is interior metal water piping only, the location of the bonding conductor no longer has to be at that within 5 feet point, and, if the exterior underground metal water piping is replaced with PVC ... and replaced all the way into the building for (let's just say) 10 feet, what was the grounding electrode conductor now becomes a bonding jumper, and (naturally) cannot be, nor needs to be, within that 5 feet of the entrance. (Whew! That was a long run-on sentence!)
    They ARE NOT attaching the #4 Bare Copper to the interior gas piping. The Gas meters are on the exterior of the dwellings. They are attaching to the INCOMING GAS LINE AHEAD OF THE METER where the piping exits the ground. Thus they are creating a Grounding Electrode out of the underground gas line. ( metallic pipe underground for 10 feet or more)

    Trust me I know about and understand all about grounding and bonding of a service.


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    Default Re: gas line bonding

    Quote Originally Posted by Jim Luttrall View Post
    Bonding and connection to the Grounding electrode are similar in look and function, really only different in intent.
    The intent of the code is to provide a Grounding electrode to communicate/dissipate to the ground. The gas line cannot be used for the purpose of a Grounding Electrode, you must provide some other GE such as water line, UFER, plate, ring, or rod. Once the Grounding electrode system is in place then EVERYTHING must be bonded to that system which is why the gas pipe system IS connected to the Grounding electrode as part of the required bonding.

    In reality the Grounding electrode is basically for surges and lightning strikes. In a ground fault of the circuit, the current is looking to go back to the source not earth. Thats why the grounded
    ( neutral) and the grounded ( Neutral) / grounding ( ground) connection is so important. Without out it the overcurrent device would not open in a fault condition.


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    Default Re: gas line bonding

    Quote Originally Posted by jack davenport View Post
    They ARE NOT attaching the #4 Bare Copper to the interior gas piping. The Gas meters are on the exterior of the dwellings. They are attaching to the INCOMING GAS LINE AHEAD OF THE METER where the piping exits the ground. Thus they are creating a Grounding Electrode out of the underground gas line. ( metallic pipe underground for 10 feet or more)
    That does not make it a grounding electrode.

    Trust me I know about and understand all about grounding and bonding of a service.
    I do know that you know a lot about grounding and bonding of a service, but that does not mean that what you described is "Thus they are creating a Grounding Electrode out of the underground gas line."

    (all caps are mine, asterisks are mine too)
    250.104(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.
    (2) Service equipment enclosure*
    (3) Grounded conductor at the service**
    (4) Grounding electrode conductor, is of sufficient size***
    (5) One ore more grounding electrodes used****

    - "in, or attached to" ... means that it can be outside
    - * The service equipment enclosure is bonded to the grounding electrode system through the grounded service conductor.
    - ** The grounded conductor at the service is grounded to the grounding electrode system.
    - *** Grounding electrode conductor ... the gas piping can be bonded directly to a grounding electrode conductor without making the gas piping a grounding electrode.
    - **** One or more grounding electrodes ... the gas piping can be bonded directly to any of the grounding electrodes without making the gas piping another grounding electrode.

    Now if ... that Big IF ... IF the gas piping you describe is the only grounding electrode, then, yes, that use would be as a/the grounding electrode and not allowed ... but you did not say that there were no grounding electrodes present, only that the gas piping system was bonded to 'something', with the implication being that the 'something' was the grounding electrode conductor, or possibly to a grounding electrode, or possibly to the service equipment and something in it.

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    Default Re: gas line bonding

    I can see the debate about the gas line being used as an electrode. It would act the same as a metallic water line effectively becoming an electrode. The only difference is that the connection is at the meter and not remote from the meter and being used as a conductor to get back to the panel.

    Jack, call me if you get a chance.

    All answers based on unamended National Electrical codes.

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    Default Re: gas line bonding

    In Theory there is NO difference in the way they are bonding the gas line then one would utilize the metallic incoming water line ..
    They both originate at the service entrance panel , terminated on the grounded conductor terminal bar ...............?

    I am not arguing the wording and your post but In reality the words do not change whats installed .....
    A pig in a dress is still a pig ............?

    Just saying ??..

    Jim I will reach out tomorrow


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    Default Re: gas line bonding

    I don't know about other parts of the country but where I worked the gas utility would have a fit if they found a connection between the incoming supply (pre-meter) gas line and the electrical panel.

    Gas meters are specifically made (isolation connection fittings) to prevent current being induced on a supply gas line. A gas line bonded supply would have just that if there were neutral supply issues as the current would use the gas line as a conductor to find a return path to the transformer. It would do this to a much smaller extent anyway as electricity seeks all paths. And, this process causes electrolysis that deteriorates the gas line, which will eventually leak and can and does cause explosions. Been there, seen that. Ain't pretty.

    Anyway, in most cases the grounding conductor used on gas appliances is sufficient to handle the required bonding of a gas line. Tying the hot and cold together at the water heater isn't a bad idea but the connection is often times made by a tub/shower valve. The requirement is the "system" be bonded, and if there is a physical connection between the hot and cold pipes then the requirement is met.

    Hopefully as plastic pipe starts replacing metallic pipe even in older residences all the "I've got a better way" crap local jurisdictions come up with regarding this stuff will start to go away.

    Last time I checked the bonding of CSST was a manufacturer's requirement and not an NEC code issue. And, so called black CSST isn't required to be bonded like the yellow variety is. Local requirements vary. See 2018 International Fuel Gas Code. Scroll down about 4 pages

    https://iccsafe.org/wp-content/uploads/PMG_CodeNotes_CSST.pdf






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    Default Re: gas line bonding

    Quote Originally Posted by jack davenport View Post
    They ARE NOT attaching the #4 Bare Copper to the interior gas piping. The Gas meters are on the exterior of the dwellings. They are attaching to the INCOMING GAS LINE AHEAD OF THE METER where the piping exits the ground. Thus they are creating a Grounding Electrode out of the underground gas line. ( metallic pipe underground for 10 feet or more)
    This confuses me.

    Around here, any buried gas pipe must be factory-wrapped (I believe the yellow stuff is PVC) to prevent corrosion. All of the more current buried pipe that is installed by the utility company is plastic. I would have thought that the PVC wrap would also essentially isolate the pipe electrically from the soil. I suppose a really high voltage could breach the PVC wrap, but it would prevent the gas pipe from being an effective grounding electrode.

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