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Copper wire vs Aluminium wire

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  • #16
    Aluminium is cheaper than copper. Thats why some countries (ive heard of France) use aluminium covered with copper, since current doesnt flow that much in the middle of the cable.
    Having copper covering aluminium makes it more protected against corrusion, and copper is a better heat conductor.

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    • #17
      probably related to corrosion of aluminium at the ground interface

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      • #18
        Originally posted by Knewron View Post
        For a good grounding system a grounding resistance of 25 ohms or less is recommended.

        Ground rods, conductors and plates are used to connect the grounding system of electrical systems to earth ground. These must be made from the material that is a very good conductors of electricity. Which is why Copper is preferred over Aluminium.
        I have read some where tht Earth resistance should be less than or equal to 1Ohm....Is it true or it could be up to 25 Ohm ?

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        • #19
          Hi dear all,
          I would like to bring some light on the subject ...
          What is a good ground resistance value?
          There is a good deal of confusion as to what constitutes a good ground and what the ground resistance value needs to be.
          Ideally a ground should be of zero ohms resistance.
          There is not one standard ground resistance threshold that is recognized by all agencies.
          However, the NFPA and IEEE have recommended a ground resistance value of 5.0 ohms or less.
          The NEC has stated to “Make sure that system impedance to ground is less than 25 ohms specified in NEC 250.56.
          In facilities with sensitive equipment it should be 5.0 ohms or less.”
          The Telecommunications industry has often used 5.0 ohms or less as their value for grounding and bonding.
          The goal in ground resistance is to achieve the lowest ground resistance value possible that makes sense economically and physically KNOW MORE



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          • #20
            It all depends on the conductivity of the material. A conductor whether it is good or bad depends on the conductivity of the material and how it changes according to temperature.
            Also, when making the above points, we are assuming that it is normal power transmission line at 50/60 Hz freq.
            Otherwise for higher freqs. skin effect is observed where we need special transmission lines.

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            • #21
              Most overlooked answer: Costs.

              We are talking about grounding wires, so theoretically they are supposed to be able to withstand a big current amount.
              Aluminum needs 1,5 to 2 times the size of copper in diameter to sufficiently deal with shorting currents, which makes it more expensive.


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              • #22
                Copper is heavier, and aluminum is lighter. The other main difference between copper and aluminum is the resistance of the material.


                Material property Copper Aluminum
                Density (@20°C) 8.94 2.70
                Electrical resistivity 16.78 28.2
                Thermal expansion 16.5 23.1
                Ultimate tensile strength 380 200

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