wrote in message ...

On Thu, 06 Oct 2011 15:31:10 -0600, Canuck57
wrote:

The oxidation was not the main problem. Was what showed up because of
the connections getting loose and then the oxidation formed, causing
fires. The aluminum has very little elastic range. Where it works like a
spring, so the aluminum actually cold flows and gets smaller under the
screw connection. Therefore getting loose. They use some special boxes
that include a spring like connector to keep the connection tight. Big
electrical lines are aluminum as the weight is significantly less and
they can run fewer towers. The 500KV main power grid lines in California
are very large aluminum wire.

And very high voltage with lower currents.

That is not true at all. Overhead transmission lines carry very large
currents, so high that the "sag" from the I2R heating causes problems.
That is one reason why our overloaded grid is so inefficient. There
are some estimates that far more than half of the power generated,
never makes to the meter.


It may have a lower current density than some local wires, but those lines
carry huge amounts of current. The wires look to be 4-6" diameter. When a
crop dusting plane hit one years ago, the plane pretty much vaporized
according to a friend who worked for PG&E near the crash.