Ground wire from panel mounts

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  • Sunking
    replied
    Originally posted by mapmaker
    btw, in all of these homes (including my former home) the 8 ft ground rods stick above ground a few inches, and the connection to the GEC is above ground. Once again, that doesn't make it right, but that is what I have observed. At least in Vermont the moisture level in the soil is not very far down.
    Most likely means before the requirement was made. With that said a single or two grounds rods do not really do anything other than a reference point to earth. Its main function is in the event your service transformer faults primary to secondary, primary distribution falls on secondary distribution or your over head service lateral, or a lightning strike on the utility or your service lateral.

    EDIT NOTE:

    With almost all new construction, no one uses ground rods any more. With the new changes over the last 25 years almost all Ground Electrodes are Concrete Encased Electrodes built into the foundation in one of the Footers. Far superior to any rod, pipe, or plate electrode.

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  • mapmaker
    replied
    Originally posted by Sunking
    To use a # 6 AWG copper, the SE cable must be 1/0 or smaller. Here is the catch. A 1/0 SE cable tells me a 100 Amp Service at most. So are you saying you live in a trailer park, apartment, or small house with a 100 amp or smaller service? Your standard 150 and 200 amp service uses a 2/0 or 3/0 SE cable and uses a #4 AWG copper GEC. See what I am saying?
    Quite clearly, thank you very much!

    The GECs that I have observed closely are indeed in older homes with 100 amp service... propane cooking and no air conditioners. I moved to my present off-grid home from a house I built in 1980 with 100 amp service.

    btw, in all of these homes (including my former home) the 8 ft ground rods stick above ground a few inches, and the connection to the GEC is above ground. Once again, that doesn't make it right, but that is what I have observed. At least in Vermont the moisture level in the soil is not very far down.

    --mapmaker

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  • Sunking
    replied
    Originally posted by mapmaker
    Regarding the use of solid wire for a grounding electrode conductor, your logic makes perfect sense to me. But is it a requirement of NEC?

    I've tried (but failed) to find language in the code that requires a solid GEC. But, I'm very new at trying to read the code, so it's not too surprising that I haven't found it if the language is there.
    No you can use, bare, stranded, insulated or bare. It is in 250.62

    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 protected against corrosion. The conductor
    shall be solid or stranded, insulated, covered, or bare.

    OK with that said you have some termination issues to solve, especially below ground level. Most Electrical Contractors (EC's)being what they are looking for fastest and least expensive method use solid because you can fine and use listed for Direct Burial Mechanical Clamps connectors for solid wire. Where as not so much for stranded wire for Direct Burial which usually requires either irreversible compression or exothermic thermal weld. DIY is kind of in the same boat as they do not have access to the proper tooling for compression and no way do they have access to the molds or training for exothermic welding.

    In Telecom and data we do use stranded in certain situations. Quite a bit in fact with just about all bonding or equipment, raised floors is done with stranded because it is easier to work with and bend and run on equipment racks. But we use 2-hole compression terminals, and H-Taps which require training and special tooling.

    As for using 6 AWG for the Ground Electrode Conductor (GEC) from the service to ground rod brings issues that have to be dealt with.


    250.64 Grounding Electrode Conductor Installation


    Grounding electrode conductors at the service, at each building
    or structure where supplied by a feeder(s) or branch
    circuit(s), or at a separately derived system shall be installed
    as specified in 250.64(A) through (F).

    (B) Securing and Protection Against Physical Damage.
    Where exposed, a grounding electrode conductor or its enclosure
    shall be securely fastened to the surface on which it
    is carried. Grounding electrode conductors shall be permitted
    to be installed on or through framing members. A 4
    AWG or larger copper or aluminum grounding electrode
    conductor shall be protected if exposed to physical damage.
    A 6 AWG grounding electrode conductor that is free from
    exposure to physical damage shall be permitted to be run
    along the surface of the building construction without metal
    covering or protection if it is securely fastened to the construction;
    otherwise, it shall be protected in rigid metal conduit
    (RMC), intermediate metal conduit (IMC), rigid
    polyvinyl chloride conduit (PVC), reinforced thermosetting
    resin conduit (RTRC), electrical metallic tubing (EMT), or
    cable armor. Grounding electrode conductors smaller than 6
    AWG shall be protected in RMC, IMC, PVC, RTRC, EMT,
    or cable armor.

    Then what catches my attention big time if the houses in your neighborhood are really using 6 AWG raises a Red Flag IMO that has to be looked at. In order to use a #6 AWG copper for the Ground Electrode Conductor (GEC) has to meet the requirements of 250.64 (2)

    (2) Individual Grounding Electrode Conductors.

    A grounding electrode conductor shall be connected between
    the grounded conductor in each service equipment disconnecting
    means enclosure and the grounding electrode system.
    Each grounding electrode conductor shall be sized in
    accordance with 250.66 based on the service-entrance
    conductor(s) supplying the individual service disconnecting
    means.

    250.66 is a Table which I cannot cut and paste but what it is telling you is the minimum size GEC is based on the Service Entrance (SE) Feeder Cable size. To use a # 6 AWG copper, the SE cable must be 1/0 or smaller. Here is the catch. A 1/0 SE cable tells me a 100 Amp Service at most. So are you saying you live in a trailer park, apartment, or small house with a 100 amp or smaller service? Your standard 150 and 200 amp service uses a 2/0 or 3/0 SE cable and uses a #4 AWG copper GEC. See what I am saying?

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  • mapmaker
    replied
    Originally posted by Sunking
    That leaves us thermal capacity and longevity. This is where solid far outperforms stranded wire especially in the dirt.
    Regarding the use of solid wire for a grounding electrode conductor, your logic makes perfect sense to me. But is it a requirement of NEC?

    I've tried (but failed) to find language in the code that requires a solid GEC. But, I'm very new at trying to read the code, so it's not too surprising that I haven't found it if the language is there.

    btw, in my area many (most?) homes use #6 stranded to connect to the ground rod. Of course, that doesn't make it right, but that is what I observe.

    --mapmaker

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  • russ
    replied
    Originally posted by merc4
    sorry guys, I didn't mean to start an argument.
    No problem - The solar shadow is gone.

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  • merc4
    replied
    sorry guys, I didn't mean to start an argument.

    Leave a comment:


  • Sunking
    replied
    Originally posted by SolarShadow
    Thanks for not addressing it with a valid answer. I proved my point.
    Give it up, you lost the debate.

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  • SolarShadow
    replied
    Originally posted by Sunking
    This tells me you are not in the profession.
    Thanks for not addressing it with a valid answer. I proved my point.

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  • Sunking
    replied
    Originally posted by SolarShadow
    Breaking my promise to say nothing..............
    So tell me then why is a ground wire allowed to be above the ground then? It is more prone to damage than a few inches of rod sticking up. My example mentioned the 10 foot rod as I recognize you'd have said at least 8 feet needed to be below ground level. If you are helping to make NEC rules and say such things here then it explains some things coming out of the NEC. Is there not a test of knowledge to be on the NEC making rules? Also, who came up with the term moisture level to be put into the rules? What an asinine vague term.
    This tells me you are not in the profession.

    Leave a comment:


  • Sunking
    replied
    Originally posted by mapmaker
    Thanks for the Mike Holt link. It seems to be not quite as black and white as you indicate in this forum. Consider this quote by 'infinity' the chief moderator:
    Look at the post dates. He is quoting 2011 code cycle. 2014 was amended from "Where Practical" to "Shall Be". The tern Shall Be in code is not a conditional statement, it means it will be done with no exceptions.

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  • Sunking
    replied
    Originally posted by Mike90250
    So, how do they do that in Palm Springs, unless the house is next to a golf course, there is no moisture level?

    Or My house pad, which is about 25' of packed gravel (extending 10' beyond the foundation perimeter). No moisture in it unless it's raining. I guess the Code is still not totally de-bugged.
    Mike you are stuck inside a box of thinking you have to use a Ground Rod. Fact is you do not have to have a single ground rod to have an acceptable functional Ground Electrode System (GES).

    III. Grounding Electrode System and
    Grounding Electrode Conductor
    250.50 Grounding Electrode System


    All grounding electrodes as described in 250.52(A)(1)
    through (A)(7) that are present at each building or structure
    served shall be bonded together to form the grounding
    electrode system. Where none of these grounding electrodes
    exist, one or more of the grounding electrodes specified
    in 250.52(A)(4) through (A)(8) shall be installed and
    used.

    Rather than copy and paste of all of A1 through A8 the electrodes on site are:

    1. Metal Under Ground Water Pipe
    2. Metal Frame of Building or Structure
    3. Concrete Encased Electrode Used in dessert conditions
    4. Ground Ring or Radials
    5. Rod or Pipe
    6. Listed systems like a Chemical Ground Rod or Radial. Used in dessert conditions
    7. Plate Electrodes most often used for large utility generators with a few thousand tons of concrete sitting on top of it.
    8. Other Local Metal Under Ground Systems or Structures.

    If none of the electrodes exist pick one from 4 through 8. Nothing says you have to use RODS. If you do use rods or pipes there are requirements to be met.

    Today most all new construction use a Concrete Encased Electrode and the Under Ground Metal Water Pipe. No ground rod or number of ground rods can beat a properly built Concrete Encased Electrode (CCE). It is a take off of the Herbert Ufer ground who worked for Dupont during WW-II and was tasked to come up with a ground system to be used in military Ammunition Bunkers located in AZ dessert where static electricity control is a must. Ufer Ground is real simple where you bond the steel reinforcement bar used inside the concrete and either stub up a section of rebar so a ground wire can be welded or compressed, or just a section of wire bonded to the rebar sticking up through the finished concrete floor. Concrete has a massive surface area and concrete never dries out. Even a small foundation can achieve extremely low impedance of less than 10 ohms. You could pound a hundred rods and never reach that low of an impedance. NEC CCE is a modified version of a Ufer Ground that only requires either 20 foot of conductor in the the bottom of a Footer, or attached (bonded) to the rebar of at least a 20 foot section.

    However I agree NEC leaves something to be desired sometimes. YOu woul dbe surprised how many EC's think a GES has to be 25 ohms or less. There is no such requirement.

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  • mapmaker
    replied
    Originally posted by Sunking
    It is exactly what it means. I use to sit on Code Panel 9 which writes Article 250. I did make one error and said Frost Line when I should have said Below Moisture Level. Any licensed electrician will tell you the rod must be below the Moisture Level. All of it not part of it. Leaving a rod above ground exposes it to physical damage. In addition the minimum requirement is a rod must be in contact a minimum of 8 feet below the moisture level and if you leave part of the rod above ground you cannot meet that requirement unless you use 10 foot or longer rods.

    Here is a very good discussion on the subject on Mike Holt Code forum that I moderate. The Forum is for professionals only, but you can read the topics. Take note it is an Inspector posting the question.
    Thanks for the Mike Holt link. It seems to be not quite as black and white as you indicate in this forum. Consider this quote by 'infinity' the chief moderator:
    Originally posted by infinity
    No one seems to know what "If practicable, rod, pipe, and plate electrodes shall be embedded below permanent moisture level" actually means. IMO the rod needs to go into the ground 8' and nothing more.
    --mapmaker

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  • russ
    replied
    Originally posted by SolarShadow
    Breaking my promise to say nothing..............
    Last chance - be polite and not a wise ass if you wish to participate.

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  • SolarShadow
    replied
    Originally posted by Sunking
    It is exactly what it means. I use to sit on Code Panel 9 which writes Article 250. I did make one error and said Frost Line when I should have said Below Moisture Level. Any licensed electrician will tell you the rod must be below the Moisture Level. All of it not part of it. Leaving a rod above ground exposes it to physical damage. In addition the minimum requirement is a rod must be in contact a minimum of 8 feet below the moisture level and if you leave part of the rod above ground you cannot meet that requirement unless you use 10 foot or longer rods.

    Here is a very good discussion on the subject on Mike Holt Code forum that I moderate. The Forum is for professionals only, but you can read the topics. Take note it is an Inspector posting the question.
    Breaking my promise to say nothing..............
    So tell me then why is a ground wire allowed to be above the ground then? It is more prone to damage than a few inches of rod sticking up. My example mentioned the 10 foot rod as I recognize you'd have said at least 8 feet needed to be below ground level. If you are helping to make NEC rules and say such things here then it explains some things coming out of the NEC. Is there not a test of knowledge to be on the NEC making rules? Also, who came up with the term moisture level to be put into the rules? What an asinine vague term.

    Leave a comment:


  • Mike90250
    replied
    Originally posted by Sunking
    .... In addition the minimum requirement is a rod must be in contact a minimum of 8 feet below the moisture level .....
    So, how do they do that in Palm Springs, unless the house is next to a golf course, there is no moisture level?

    Or My house pad, which is about 25' of packed gravel (extending 10' beyond the foundation perimeter). No moisture in it unless it's raining. I guess the Code is still not totally de-bugged.

    Leave a comment:

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