I was looking at the data sheet for a copper cable and noticed the conductor resistance to be specified at around 5 mOhm/m. This is magnitudes higher than pure copper, which has a resistance in the order of 10 nOhm*m. Why is the resistivity so much higher?

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Lucille Lucas · Accepted Answer

The resistivity of a metal gives the resistance it will have based on the cross-sectional area and the length of the conductor.  ρ  =            A      R        L  This means that resitivity is in SI units of   Ω   m . Neither of your quoted figures are in such units. Copper has a resistivity around   1.68  ×      10          −      8        Ω   mUnlike the bulk metal, a wire or conductor is manufactured with a constant cross section. If you pull the cross section away, you can characterize it with resistance per length, or       Ω    m  .In fact, assuming the wire above is copper, we can calculate the size based on linear resistance figure given.  ρ  =            A      R        L    A  =      ρ          R      L        A  =            1.68      ×              10                  −          8                    Ω       m              5      ×              10                  −          3                    Ω               m                  −          1                      A  =  3.36  ×      10          −      6            m    2    =  3.36      mm    2  That cross section happens to be quite close to that of 12 gauge (AWG) wire.

I was looking at the data sheet for a copper

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