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Thread: Ground rod versus Ufer

  1. #1
    Join Date
    Apr 2008
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    4

    Ground rod versus Ufer

    New guy here with a question. I always try to run a #4 cu conductor to rebar in footer. On a house I was wiring the footer was already poured so I put the conductor on the foundation rebar which was wire tied to the foundation rebar. I was also planning to set a ground rod outside of the house after the framing was completed. Home owner arrived and saw no ground rod just the wire attached to the rebar. He contacted the GC and told him that it needed a ground rod. GC called me and I explained to him that I was planning to drive one outside of the house at the same time I set the main panel. A few days later the home owner stopped by, didn't' see a ground rod, called the gc and told the gc to fire me.

    As it turns out he had someone else he wanted to wire the house anyway so it seems that he was just looking for something to get rid of me but was to cowardly to just do it the stand up way. I could care less if he wants someone else to wire his house.

    Any way I called him up to explain what I was doing and to find out what he wanted to do about the temp service that was my property. He went off about how he had talked to a "electrical engineer" who had said that you absolutely do not use rebar to ground to. He also tried to explain how the rebar was just laying in the concrete and hadn't been driven into the ground in the footers and that there was plastic and foam insulation under the floor.:rolleyes: He obviously thought that concrete is a insulator.

    Here's my question. He drove a ground rod at an angle and bent it up into the wall line. He's planning to attach his ground to the rod under the panel. I told him that it had to be accessible so he's planning to frame an opening so he can get to the clamp. What's the regs on setting a ground rod. Does it need to be outside. I'm not sure if the rod is at less than a 45 Degree angle or not but he talked about driving it at an angle because there is rock.

    Also I have always been under the impression that is a grounding source is present that you are required to run a grounding conductor to it. Is that correct? 250.50

    According to 250.50 C is it a good ground if you attach the ground wire to a rebar that is bent up out of the foundation and attached to the rest of the rebar in the foundation. According to this website that explains grounding, the network of rebar is considered to be one. http://www.creia.org/files/public/gr...ode_locked.pdf

    Code:
    Many jurisdictions require this steel to be in addition to the steel that is already present, despite the fact that the code does not intend for it to be anything other than the original steel. Because of this wide spread misunderstanding, the NEC added language to the 1999 edition stating that the ordinary tie wires between pieces of reinforcing steel are considered sufficient for bonding the sections of steel to each other.
    My understanding is that a ufer ground is superior to a ground rod and that in fact a ground rod would not be needed if it were not for inspectors that required it. Right or wrong?

    Please ejumacate me because if I'm grounding improperly then I'm the first to want to change my wiring methods to comply.:cool:

  2. #2
    Join Date
    Dec 2006
    Location
    Chapel Hill, NC
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    26,412
    Your homeowner is making a mistake for the ufer ground is a superior ground if installed correctly. If the rebar is indeed tied together and at least 1/2" then you are suppose to use the CEE and no ground rod is necessary.

    The first lightning strike and I bet it will blow a hole in the slab if installed indoors. I have seen that happen, however, I don't believe that it is a violation. An ugly install, yes indeed.

  3. #3
    Join Date
    Feb 2003
    Location
    Minnesota
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    4,983
    Welcome to the Forum, EIT.

    I agree with Dennis.
    Quote Originally Posted by EIT
    On a house I was wiring the footer was already poured so I put the conductor on the foundation rebar which was wire tied to the foundation rebar.
    If connection to the rebar of the foundation footing (Ufer) is available, after the pour, and the local electrical inspector and footing inspector are on the same page, then 250.50 tells us that the Ufer must be used.

    This homeowner's idea about avoiding connection to the footing is not only wrong, but puts him in the role of writing his own electrical code. Firing you and hiring another electrician will not excuse him from complying with the NEC.

    The requirements for ground rod installation are in 250.53(G). The NEC Handbook adds this explanatory (not enforceable) text after 250.53(G):
    All rod and pipe electrodes must have at least 8 ft of length in contact with the soil, regardless of rock bottom. Where rock bottom is encountered, the electrodes must be either driven at not more than a 45-degree angle or buried in a 21/2-ft-deep trench. It should be noted that driving the rod at an angle is permitted only if it is not possible to drive the rod vertically to obtain at least 8 ft of earth contact. Burying the ground rod is permitted only if it is not possible to drive the rod vertically or at an angle.
    Ground clamps used on buried electrodes must be listed for direct earth burial. Ground clamps installed above ground must be protected where subject to physical damage
    Another Al in Minnesota

  4. #4
    Join Date
    Apr 2008
    Posts
    4
    Something I neglected to mention is that this was going to be a job that was not going to be inspected at any time. Neither the town or county have a code inspector. FWIW I would rather wire for a strict grumpy inspector than in a region that does not have any code enforcement.

  5. #5
    Join Date
    Feb 2003
    Location
    Minnesota
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    4,983
    Quote Originally Posted by EIT
    . . .a job that was not going to be inspected at any time.
    Remind the homeowner that if he is ever to insure this home, that the insurance company won't be able to find a copy of the personal code of the homeowner, only the National Electrical Code.

    Insurance companies are one of the big forces in creating the NEC.
    Another Al in Minnesota

  6. #6
    Join Date
    Jul 2004
    Location
    Ca and Wa
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    Quote Originally Posted by EIT
    http://www.creia.org/files/public/grounding_electrode_locked.pdf[/URL]


    My understanding is that a ufer ground is superior to a ground rod and that in fact a ground rod would not be needed if it were not for inspectors that required it. Right or wrong?
    EIT, The above creia.org sites Figure 1 is not correct. The Ufer GEC must not be spliced as shown bonded to the water pipe, it must be continuous into the main disconnect enclosure bonded ground bar. The clamping splice may wash by some AHJ's in commercial but is a no-no in residential. [250.64(C)]Continuous

    The two main common electrodes (if available) per 2008 NEC are [250.52(A)(1)] direct buried 10' metal water pipe and [250.52(A)(3)] encased electrode #4x20' either CU or rebar. rbj
    rbj, Seattle...Safety is a Professional Courtesy.

  7. #7
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    Jul 2004
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    Ca and Wa
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    Creia

    EIT,

    Forgot to mention that CREIA is the California Real Estate Inspection Association that is a private agendized company that do home inspections.

    I collect HI books and rate these guys as charging too much for the service they attempt to present. rbj
    rbj, Seattle...Safety is a Professional Courtesy.

  8. #8
    Join Date
    Jun 2007
    Posts
    481
    Ground rod needs to go below finished grade. At least where I live! I'm feeling to lazy to read 250.. Are you still letting them use your temp and your permit for it? Screw them. Call the POCO. Tell them to disconnect and go get your temp. I'd also show up and vigorously remove any material I had installed. Oh yeh and next time get a contract so they can't decide to screw you just because the homeowner flaked out.

  9. #9
    Join Date
    Feb 2006
    Location
    new york
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    4,258
    Tell the homeowner to ask his engineer if he understands parallel paths in an electrical circuit. Then ask him to calculate what the resistance to ground is with unlimmited (infinity ) parallel paths for any resistance with the weight of the entire house holding the ground in contact with the earth.
    The tail does NOT wag the dog.

  10. #10
    Join Date
    Jul 2004
    Location
    Ca and Wa
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    electrodes

    What wireman says.

    Tell the HO to stick it and that the bottom line is, if you have installed a #4 Cu wire to the stemwall foundation 20' rebar....GROUND RODS are not needed. rbj
    rbj, Seattle...Safety is a Professional Courtesy.

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