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Bonding when rebar is in concrete and structure is bonded to rebar

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    Bonding when rebar is in concrete and structure is bonded to rebar

    We are an ungrounded system. I have for years put in ground rods, bonded them to rebar and cadwelded the 2/0 copper to any steel structure that may become energized for the protection of personnel whenever we pour concrete for equipment. Am I thinking wrong that if the rebar encased in concrete is not tied to ground and the metal in the area that there is a difference of potential if the person walking by touches the metal and is standing on the ground if a fault were to occur in the metal. Some of the electricians on our site says just laying the copper on the rebar is sufficient grounding. I tell them we are not grounding, we are bonding and we need to do this in case of either stray voltages or ground faults on the system. What says the forum? Is this considered a grounding grid, equipotential plane or just bonding? How should a new installation be done today that suffices the NEC?

    #2
    Take a look at what the code requires for a grounding electrode system. 250.50 - 250.70. That is all that is required.

    You cannot reliably trip the OCPD if you use the concrete as part of the ground fault path.

    Stray voltage and equipotential grounding is more about tiny voltages that you cannot even feel that will cause cows to produce less milk and applies to dairy barns mostly, and to swimming pools. Not much eslewhere.

    Bob

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      #3
      Please take a look at 250.4 (A) grounded systems and 250.4(B) ungrounded systems, and note the difference My understanding is an ungrounded system does not have the system bonding jumper installed but other than that all the grounding and bonding is the same, and a ground detector is required.
      Moderator-Washington State
      Ancora Imparo

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        #4
        At what point do we call it an Ufer ground and not a bond?

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          #5
          Originally posted by Hv&Lv View Post
          At what point do we call it an Ufer ground and not a bond?
          A CCE according to the NEC does not have to be all the rebar, only a 20' stick. Ufer was a dude who showed us how effective a CCE can be.
          If Billy Idol is on your playlist go reevaluate your life.

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            #6
            Originally posted by ActionDave View Post

            A CCE according to the NEC does not have to be all the rebar, only a 20' stick. Ufer was a dude who showed us how effective a CCE can be.
            So how do you bond to it? Doesn’t the steel have to be corrosion proof now?
            Leave a piece of rebar sticking out, or cadweld, or just use a ground rod clamp?

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              #7
              Originally posted by Hv&Lv View Post

              So how do you bond to it?
              All of the steel? You don't

              Doesn’t the steel have to be corrosion proof now?
              I don't know what do you mean?


              Leave a piece of rebar sticking out, or cadweld, or just use a ground rod clamp?
              All are effective.

              If Billy Idol is on your playlist go reevaluate your life.

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                #8
                Originally posted by gastoor View Post
                We are an ungrounded system. I have for years put in ground rods, bonded them to rebar and cadwelded the 2/0 copper to any steel structure that may become energized for the protection of personnel whenever we pour concrete for equipment. Am I thinking wrong that if the rebar encased in concrete is not tied to ground and the metal in the area that there is a difference of potential if the person walking by touches the metal and is standing on the ground if a fault were to occur in the metal. Some of the electricians on our site says just laying the copper on the rebar is sufficient grounding. I tell them we are not grounding, we are bonding and we need to do this in case of either stray voltages or ground faults on the system. What says the forum? Is this considered a grounding grid, equipotential plane or just bonding? How should a new installation be done today that suffices the NEC?
                I think the most important thing to do is make sure that all the exposed metal parts are solidly connected and not worry so much about what is going on underground.
                If Billy Idol is on your playlist go reevaluate your life.

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                  #9
                  Originally posted by ActionDave View Post

                  I don't know what do you mean?
                  250.68(C)(3).
                  I looked it up after I posted the question.
                  wasn't sure if I knew what I was asking...
                  corrosion proof. It’s 2017 NEC
                  not sure which cycle your on.

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