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  1. #1
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    Default Elec grounding question

    Hello all,
    First post, I really learn alot from this forum, thanks.
    I ran into this senario and was scratching my head.
    SE has a #4 awg apparently tied into the footing, (wire goes down thru the slab anyway). But I saw this at the water main. Main is Poly-E with copper supply throughout.
    Ground wire (green wir in picture) runs back to the panel.
    How is this functional?
    Thanks for the help.
    Mike P.
    Baltimore

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  2. #2
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    Default Re: Elec grounding question

    Regardless of the plastic main, the copper plumbing needs to be bonded, so maybe that's what the green conductor is intended for.


  3. #3
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    Default Re: Elec grounding question

    Thanks John, but how does this wire accomplish anything it goes straight to the ground buss at the panel?


  4. #4
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    Default Re: Elec grounding question

    Quote Originally Posted by Mike Picarello View Post
    Thanks John, but how does this wire accomplish anything it goes straight to the ground buss at the panel?
    So, now that the conductor is clamped to the copper pipe, if a hot wire were to come loose somewhere and touch a metal pipe (assuming all the metal pipes are connected/bonded), instead of just sitting there waiting for you to come along and touch it and get shocked, the current can flow back to the source (usually the transfomer) and thereby trip the overcurrent device (breaker, fuse).


  5. #5
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    Default Re: Elec grounding question

    All metal piping systems (water, gas, air, etc.) should be bonded back to the building grounding electrode system. This does not provide grounding for the electrical system, it prevents the piping systems from being energized and hurting people. You want the overcurrent device to trip, and bonding makes this possible.

    Jim Luttrall
    www.MrInspector.net
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  6. #6
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    Default Re: Elec grounding question

    See if this helps. I also suggest checking out some of the previous threads here as well as Mike Holt or Doug Hansen for an explanation of grounding and bonding.
    Mike Holt

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    Jim Luttrall
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  7. #7
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    Default Re: Elec grounding question

    Quote Originally Posted by Jim Luttrall View Post
    All metal piping systems (water, gas, air, etc.) should be bonded back to the building grounding electrode system. This does not provide grounding for the electrical system, it prevents the piping systems from being energized and hurting people. You want the overcurrent device to trip, and bonding makes this possible.
    As far as the overcurrent device goes, it's the low impedance path back to the source that allows for sufficient current to flow to trip the breaker or blow the fuse.
    The grounding electrode path is relatively high impedance and is mainly for high voltage events, like lightning, and to stabilize voltage.


  8. #8
    Richard Pultar's Avatar
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    Default Re: Elec grounding question

    If the main was metal it would be required.
    I know some guys do stuff like this because they rather not have to explain how the code is clear that it is not required to the inspectors.


  9. #9
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    Default Re: Elec grounding question

    Quote Originally Posted by Richard Pultar View Post
    If the main was metal it would be required.
    Richard,

    It is required anyway.

    I know some guys do stuff like this because they rather not have to explain how the code is clear that it is not required to the inspectors.
    Please explain to me why you think it is not required.

    Aren't you the same Richard who thinks home owners should be allowed to build whatever they want, regardless of what code requires, and regardless that they may some day sell to some other family? Please tell me I am wrong and have you confused with another Richard.

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  10. #10
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    Default Re: Elec grounding question

    Quote Originally Posted by Jim Luttrall View Post
    See if this helps. I also suggest checking out some of the previous threads here as well as Mike Holt or Doug Hansen for an explanation of grounding and bonding.
    Mike Holt
    Jim,

    The one problem that I have with the diagram that you posted is that the hot water is not clearly bonded. Both hot & cold are required to be bonded. At least, around here they are.

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    Default Re: Elec grounding question

    Quote Originally Posted by Gunnar Alquist View Post
    The one problem that I have with the diagram that you posted is that the hot water is not clearly bonded.
    Depends.

    If not dielectric unions are installed, then the hot and cold are bonded through the water heater. This can be done with brass fittings when using copper piping. When using galvanized piping in older homes, that also did the trick.

    Both hot & cold are required to be bonded. At least, around here they are.
    When dielectric unions are installed, yes, that would be needed. Many dielectric fittings maintain mechanical and electrical contract while lining the interior of the fitting with plastic to isolate the fitting from the water, those also maintain bonding contact.

    It is quite probable that, to ensure that future repairs do not 'break the bond', that the hot piping needs to be bonded to the cold piping. Makes sense and is a 'good thing to do', but "required"? Not knocking it, anything which improves it is good with me, just pointing out the other side of why many areas do not "require" it.

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  12. #12
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    Default Re: Elec grounding question

    Regarding the graphic supplied by Jim, with the exception of a bond across the hot and cold lines at the water heater this is typically what I run into. The water heater lines are bonded at this house. So am I correct in saying that the green wire in this picture is protection for the metal piping/people within the house in the event that a line becomes energized?


  13. #13
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    Default Re: Elec grounding question

    Quote Originally Posted by Jerry Peck View Post
    It is quite probable that, to ensure that future repairs do not 'break the bond', that the hot piping needs to be bonded to the cold piping. Makes sense and is a 'good thing to do', but "required"? Not knocking it, anything which improves it is good with me, just pointing out the other side of why many areas do not "require" it.
    JP,

    My understanding is that it is required... At least around here it is. And, just for the reason that you noted; when the WH is changed out. This from a local electrical contractor. Bonding jumper from the cold to the hot and down to the gas supply on the water heater (when it is a gas water heater). I have been seeing it on most new construction.

    However, I have not noticed whether or not dielectric fittings are always present on the water heater connections.

    Last edited by Gunnar Alquist; 11-20-2008 at 08:46 PM.
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    Default Re: Elec grounding question

    Quote Originally Posted by Mike Picarello View Post
    Regarding the graphic supplied by Jim, with the exception of a bond across the hot and cold lines at the water heater this is typically what I run into. The water heater lines are bonded at this house. So am I correct in saying that the green wire in this picture is protection for the metal piping/people within the house in the event that a line becomes energized?
    Mike,

    I think that is a reasonable assumption. That is the way bonding is done. However, I am not there and a single pic is difficult to determine absolutely. In addition, around here, #6 solid is required for bonding. That looks like stranded. If I remember correctly, stranded is not allowed for the GEC. Not sure if it is allowed for the bonding conductor. Is it aluminum? Kind of looks like it from the pic.

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  15. #15
    Richard Pultar's Avatar
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    Default Re: Elec grounding question

    The only reason why the bonding jumper is at the water heater is because its easy to determine that the bond is intact. This bond from hot to cold metal pipe can be anywhere in the system. In a finished basement the water pipes are usually hidden from view. The water heater is always visible.
    A ground connection must be made within 5 ft of point of entrance of metal underground water pipe.
    This picture is typical of a person not caring that the underground water pipe is plastic.
    I have seen bonding jumpers on plastic pipe at water heaters.
    Bonding requirements are not the same as grounding requirements.


  16. #16
    Christopher Gorton's Avatar
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    Default Re: Elec grounding question

    Wires running through metal box with no grommet or clamps.
    What's under the duct tape beside the burn mark? Sawcut?


  17. #17
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    Default Re: Elec grounding question

    Quote Originally Posted by Gunnar Alquist View Post
    ...That looks like stranded. If I remember correctly, stranded is not allowed for the GEC...
    See Stranded wire - InspectionNews.com .

    Unless it's changed,

    From the 2002 NEC.

    "250.62 Grounding Electrode Conductor Material.
    The grounding electrode conductor shall be of copper, aluminum, or copper-clad aluminum. The material selected shall be resistant to any corrosive condition existing at the installation or shall be suitably protected against corrosion. The conductor shall be solid or stranded, insulated, covered, or bare."


  18. #18
    Richard Pultar's Avatar
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    Default Re: Elec grounding question

    it did not change


  19. #19
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    Default Re: Elec grounding question

    Quote Originally Posted by Richard Pultar View Post
    This picture is typical of a person not caring that the underground water pipe is plastic.
    No, that is a photo of a person who actually understands that it does not matter that the underground water pipe is plastic.

    They understand that they are bonding the interior metal water piping system to ground.

    They understand that they are not grounding the panel to the metal water piping.

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  20. #20
    Brian Thomas's Avatar
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    Default Re: Elec grounding question

    Quote Originally Posted by Jerry Peck View Post
    No, that is a photo of a person who actually understands that it does not matter that the underground water pipe is plastic.

    They understand that they are bonding the interior metal water piping system to ground.

    They understand that they are not grounding the panel to the metal water piping.

    How can you be sure of this person's intention? And whether they did indeed know what they were doing? Im just asking because its just one photo of a green wire clamped to copper piping. How can you be sure what the installer understood based off this one photo?

    Not trying to stir the pot, just trying to understand the line of thinking here. You may be 100% correct i just wanna learn more about bonding and grounding because its something that i dont fully understand yet


  21. #21
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    Default Re: Elec grounding question

    Quote Originally Posted by Richard Pultar View Post
    This picture is typical of a person not caring that the underground water pipe is plastic.
    Quote Originally Posted by Jerry Peck View Post
    No, that is a photo of a person who actually understands that it does not matter that the underground water pipe is plastic.
    Quote Originally Posted by Brian Thomas View Post
    How can you be sure of this person's intention?
    We (neither Richard nor myself) can, however, I am sure that my presumption of what was being done has a much higher probability of being correct than the assumption Richard made.

    I base this on two things: 1) because that is being supplied some type of non-metallic pipe (which, by the way, does not look to be an approved pipe for inside a structure, nor does the clamping look like an approved connection); 2) the fact that Richards posts seem to have one thing in common - screw the code, do it anyway you want, and if something is done, it just has to be done by a stupid person (not that that would matter based on the attitude of screw the code, seems that would indicated that no bonding or grounding was necessary, and the person doing that was just wasting wire).


    i just wanna learn more about bonding and grounding because its something that i dont fully understand yet
    This is the difference between grounding and bonding.

    With grounding, you are intentionally taking something to earth, i.e., "ground"ing it to earth ground.

    With bonding, you have no concern where "earth" or "ground" is, you simply want to tie it all together at the same equipotential plane. That means that, in the case of bonding metal piping to ground, touching the metal piping anywhere along the metal piping will essentially be similar to touching earth.

    Bonding gets confusing because you have "bonding to ground" (such as interior metal piping systems) and "bonding to create an equipotential plane" (such as at swimming pools and spas).

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