Copper Electrical Conductivity

The electrical conductivity of copper is
second only to silver. The conductivity of
copper is 97% that of silver. Due to its
much lower cost and greater abundance,
copper has traditionally been the standard
material used for electricity transmission
applications.
However, weight considerations mean that
a large proportion of overhead high voltage
power lines now use aluminium rather than
copper. By weight, the conductivity of
aluminium is around twice that of copper.
The aluminium alloys used do have a low
strength and need to be reinforced with a
galvanised or aluminium coated high tensile
steel wire in each strand.
Although additions of other elements will
improve properties like strength, there will
be some loss in electrical conductivity. As
an example a 1% addition of cadmium can
increase strength by 50%. However, this
will result in a corresponding decrease in
electrical conductivity of 15%.