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    Bonding jumper/GEC

    Bonding jumper/GEC

    New postby Marc M on Mon Oct 14, 2013 11:19 am

    Jerry, is it possible to utilize the GEC as a cold water bonding jumper also or is a separate conductor always required?
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    Re: Bonding jumper/GEC

    New postby Jerry Peck - Codeman on Mon Oct 14, 2013 1:55 pm

    I can't think of when the GEC could be installed to serve as a bonding conductor for the interior metal water piping system.

    The closest I can think of would be when a GEC might be connected to an underground water pipe in a basement before the water meter and someone tried to use it as the bonding conductor to the interior metal water piping; however, doing so would be a conflict between the two different uses.

    Doing so would also be a conflict between the definitions of the two and would make its use incompatible with either, or both, definitions.

    I will need to look in the code to verify, but I would say that it is not allowed to be used for both - thus a separate conductor would be needed for each.
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    Re: Bonding jumper/GEC

    New postby Jerry Peck - Codeman on Mon Oct 14, 2013 6:37 pm

    Marc,

    I didn't have my codes with me earlier, here are the definitions:
    - Grounding Electrode Conductor. A conductor used to connect the system grounded conductor or the equipment to a grounding electrode or to a point on the grounding electrode system.
    - Bonding Jumper. A reliable conductor to ensure the required electrical conductivity between metal parts required to be electrically connected.

    The two definitions are almost mutually exclusive:
    - a) GEC connects the service equipment with the grounding electrode system (which could be an underground metal water pipe)
    - b) Bonding Jumper connects the interior metal water piping to the service equipment
    - c) Bonding Jumper connects the interior metal water piping to the grounding electrode conductor
    - d) Bonding Jumper connects the interior metal water piping to the grounding electrode system

    If the interior metal water piping system is connected by method c) or d), then it could appear that the bonding conductor is serving as the GEC, even though the bonding conductor serves a different purpose.

    An easy way to think of these may be as follows:
    - The GEC connects the service equipment/grounded conductor to ...
    - The Bonding Jumper connects the interior metal water piping to ...

    Back to my previous scenario:
    "The closest I can think of would be when a GEC might be connected to an underground water pipe in a basement before the water meter and someone tried to use it as the bonding conductor to the interior metal water piping; however, doing so would be a conflict between the two different uses."

    Let's presume that 5 feet or so of the underground metal water piping is sticking into the basement, that the underground metal water piping is being used as the grounding electrode (now requires a supplemental electrode such as a ground rod) and the GEC is from the service equipment in the basement to the exposed section of the underground metal water pipe. That is a permitted connection to a permitted grounding electrode.

    Now we have a water meter in the line after the connection point of the GEC to the water pipe, the metal water pipe from the water meter and into the house is the 'interior metal water piping system' and needs to be bonded to ... let's use d) above ... the grounding electrode system - the grounding electrode system is on the other side of the water meter, so the Bonding Jumper for the interior metal water piping system is the jumper which is installed to jump around the meter, that Bonding Jumper around the water meter must be sized according to Table 250.66:
    - From Table 250.66
    - largest service entrance conductor = bonding jumper size
    - - 2 or smaller copper -or- 1/0 or smaller aluminum = 8 copper -or- 6 aluminum bonding jumper size
    - - 1 or 1/0 copper -or- 2/0 or 3/0 aluminum = 6 copper -or- 4 aluminum bonding jumper size
    - - 1/0 or 3/o copper -or- 4/0 or 250 kcmil = 4 copper -or- 2 aluminum bonding jumper size

    Did I cover what you saw?
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    Re: Bonding jumper/GEC

    New postby Marc M on Tue Oct 15, 2013 1:00 am

    EGC, GEC...these are confusing especially if you see someone using them incorrectly..
    Okay, I found this....
    250.121 Use of Equipment Grounding Conductors. An
    equipment grounding conductor shall not be used as a
    grounding electrode conductor.

    I think this is where I was going.
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    Re: Bonding jumper/GEC

    New postby Jerry Peck - Codeman on Tue Oct 15, 2013 7:05 am

    The bonding jumper from the metal water piping is not an equipment grounding conductor - of course, that may be what I read into the question that you were asking about, but which may not have been stated. My error.
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    Re: Bonding jumper/GEC

    New postby Marc M on Tue Oct 15, 2013 4:22 pm

    Dumb question...what if for example there is an install like the one in the image. Is it a EGC / bond or a GEC that is not jumped past the meter?
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    Re: Bonding jumper/GEC

    New postby Jerry Peck - Codeman on Tue Oct 15, 2013 7:06 pm

    Marc,

    I zoomed in on that photo and the size of the conductor (whatever its purpose is) looks to be quite small, like a #10 or even a #12 - what size did it look to be in real life up close and personal?

    It would need to be at least a #8 to be a bonding jumper for the interior metal water piping ... er ... to be a 'properly sized' bonding jumper.

    Also way too small to be a GEC.

    The outer metal covering (flexible metal conduit) is improperly terminated and clamped to the water pipe - back then (how old is the house? looks old, like maybe 1960s or older?) ... back then, when I see EMT or flexible metal conduit over the GEC, they are always terminated in a proper fitting made just for that purpose. During the 1970s and 1980s, though, there seemed to be more of a 'Git R Done' attitude, whereas today people are again beginning to realize that things like that need to be done closer to the right way than just 'Git R Done'.

    Do you know where the other end of that conductor goes to - that should help determine what its purpose was/is.
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    Re: Bonding jumper/GEC

    New postby Marc M on Wed Oct 16, 2013 10:11 am

    Hey Jerry, this is an old 30's house with a new service upgrade. I traced this conductor to the main service panel to the G bus. here it is blown up..
    So another house yesterday has a similar issue. Conductor to the main, but the main was actually plastic so I can only guess that since the water main and panel are both original, this is an EGC? (bond) and not a GEC ..
    My problem is that in the field, and when we cant trace the conductors, its hard to tell them apart in this situation.
    I should add that I normally see the EGC at the water heater.
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    Re: Bonding jumper/GEC

    New postby Jerry Peck - Codeman on Wed Oct 16, 2013 1:13 pm

    Marc,

    The larger photo of the connection shows things a lot better, thanks ... what I thought I saw as the conductor in the smaller photo was actually just the one upward turned strand in the larger photo.

    From the size of the conductor in the flexible metal conduit I am guessing that was 'intended' to be the GEC and that they were/are using the metal water piping going into the ground as the grounding electrode.

    Marc M wrote:Hey Jerry, this is an old 30's house with a new service upgrade. I traced this conductor to the main service panel to the G bus.


    Being as they had the service replaced, they should have installed proper grounding electrodes, GEC, and Bonding Jumpers. Whenever I inspect service upgrades for code inspections (which is often and quite a number of them) the contractor is required to 'prove' that the metal water piping they are using as a grounding electrode actually has at least 10 feet in the ground because so many water service pipes (copper and galvanized) have been replaced with PVC (which negates the water pipe from being used as a grounding electrode).

    If the water pipe is at least 10 feet into the ground, then they are required to provide a supplemental grounding electrode (drive a ground rod at least 6 feet from the water pipe); however, if they cannot, of chose not to, show that at least 10 feet of water pipe is in the ground, then they drive two ground rods at least 6 feet apart. The GEC from the new service equipment is required to be unbroken/unspliced between the service equipment and the first grounding electrode (the code offers options to the 'unspliced' part by allowing irreversible crimp connections or exothermic welding to make a splice *permanent* and be treated as not being spliced).

    With metal for the interior water piping system, they are also required to install a proper bonding jumper to the metal water piping is they cannot show that one already exists.

    In the case as you have described it, the new service upgrade would have required a bonding jumper inside to the metal water piping, a GEC to the water pipe outside (if they could show there was at least 10 feet of metal pipe in the ground) AND a driven ground rod at least 6 feet from the water pipe; can't show the metal water piping is at least 10 feet in the ground and they drive TWO ground rods at least 6 feet apart.

    A good way to insure that they meet the 6 feet minimum is to lay the second ground rod with its head next to the first ground rod, then pick the head of the second ground rod up, keeping the point on the ground where it was, when the second ground rod is straight up, it is 8 feet from the first as the ground rood will be 8 feet long. That solves the problem of measuring out 6 feet, picking up a ground rod, then driving it at 5 feet 11 inches ... which is not good when 6 feet is the minimum required distance between the two grounding electrodes.

    So another house yesterday has a similar issue. Conductor to the main, but the main was actually plastic so I can only guess that since the water main and panel are both original, this is an EGC? (bond) and not a GEC .


    I can only surmise that whomever did an installation like that did not understand or grasp the concept that plastic water pipe (CPVC) does not conduct electricity so there is no need to bond it to ground, nor can it be used as a grounding electrode. Yes, I have heard of code inspectors requiring plastic piping to be bonded, but once the concept is discussed with them they understand that there is no reason to bond plastic water piping - I this practice stopped back in the mid-to-late 1990, or at least I would hope that this practice was stopped by the mid-2000s.

    My problem is that in the field, and when we cant trace the conductors, its hard to tell them apart in this situation.


    I completely agree that can be a problem, and if you cannot verify where the conductors comes from/goes to, then I would not address the conductor as being either the GEC or the bonding jumper, or anything else for that matter ... just state that one of one conductor was found at (panel, water pipe, etc) but the other end was not found, thus its intended purpose is not known.

    I should add that I normally see the EGC at the water heater.

    You would see the EGC at the plate where the water heater wiring is connected into the water heater junction box. If you see a conductor connected to one of the water lines connected to the water heater then that conductor would be (*most likely* 'would be') the bonding jumper from the service equipment to the interior metal water piping.

    There will be times when you cannot find any conductor for either the GEC or the bonding jumper, I recommend adding that to the electrical items something like this: Have electrical contractor verify, and document, that the electrical system is properly grounded to a grounding electrode system and that the service equipment is properly bonded to any/every interior metal water piping system. That way, when the electrical contractor goes out to make other repairs they can verify and document those items. What kind of documentation is acceptable? Photos would be nice, but what would be better, and photos attached to it would be even better, would be a letter, on electrical company letterhead, stating that the electrical system grounding was checked and that it is properly grounded, and that the metal interior water piping is properly bonded. How do you know? You don't, all you have are those letters saying that 'Yep, I done did it, no problem now.', which is only as good as the electrical contractor, but it is really the only thing you can do other than verifying and documenting it yourself - which I would stay away from.

    That you you can say: "Your Honor ... " ... " ... here is a letter from a licensed electrical contractor stating that they checked the grounding of the electrical system and said it was good and done properly. They also said they checked the metal water piping bonding and said it was good and done properly." Then follow that with: "Here is the name, phone number, and address of the electrical contractor should you desire to ask them how they checked the grounding and bonding and to what standard it was done properly to."
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