Re: [Phys-L] aluminum resistivity

[brian whatcott <betwys1@sbcglobal.net>]

In 1913, a standard for commercially pure annealed copper was 
established by International Electrotechinical  Commission (IEC). This 
is 1.7241E-8 ohm-meter.
Since then, other commercial conductors are rated in terms of a percent 
conductivity of the IEC standard for annealed copper.
<https://www.nde-ed.org/GeneralResources/IACS/IACS.htm>

This ranges from as high as 103% IACS   (for modern methods of purifying 
copper)
to  61% to 62.6% IACS for 1350 aluminum (Aluminum which contains less 
than 1% of impurities) and  18% IACS for iron.
Overhead aluminum cables carry support core wires of steel which are 
said to contribute little to heating effect at AC frequencies where the 
(60Hz) skin depth may be limited to 9 mm in a 25 mm cable.
I notice that the range 61% to 62.6% of IACS conductivity represents an 
aluminum resistivity of  28.26 nano ohm-meter   to 27.54 nano ohm-meter.
The lower resistivity value (26.5 nanohm.m) that Anthony gives for 
aluminum  is likely to have derived from high-purity annealed samples of 
aluminum, which are not used in high voltage overhead power lines.

Brian Whatcott    Altus OK    Indian Territory.


On 7/21/2014 10:05 AM, Anthony Lapinski wrote:
> I was doing a quick calculation for the resistance of a high-voltage power
> line. I looked online for the resistivity of aluminum, but was getting
> conflicting results. In units of nanoohm-meters, some had 28.2 while
> others had 26.5. I realize the effect is very small, but I was surprised
> by these discrepancies. Does anyone know what the "actual" value should be?
>
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