I am an early adoptor of technological advancements. There have been downsides to this propensity because of ill conceived "improvements" (think CFL lighting). As an electrician in the 70's, I installed many aluminum branch circuits with 10 and 12awg aluminum conductors. As an electrician in the 90's, 00's, 10's...and continuing to today, I deal with the flawed technology that was adopted when copper became too expensive and aluminum was foisted on the industry without adequate testing.
That said, the white paper is compelling. It was proposed that the main objections to CCA were skin effect (please, I've spent too much time in high frequency to lend credibility to that theory(i.e. waveguide). Current acts more like DC at 60hz than it does at gigahertz). The other is a metallurgical question which I am profoundly inadequate to challenge.
In my experience neither of the aforementioned issues are of primary consequence. My greatest objection to AL conductors, clad or unclad, as it were, is mechanical strength. The white paper addresses the oxidation issue which caused a resistive connection at the termination point, with its inherent heat, but didn't address the less malleable properties of AL vs CU. AL will suffer reconnection less reliability than copper and, over time, the relatively brittle nature of aluminum(when compared to copper) is the crux of the issue.
In my experience failure of small wire gauge AL has been largely mechanical, not electrical.
Broken wires at termination points have been the overwhelming cause of failure.
Has this propensity been evaluated? Ken Johnson August 30 2023, 8:25 pm EDT
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Some in the electrical industry hold two beliefs about copper-clad aluminum (CCA) conductors when used in power circuit applications. One of these beliefs is that conductors of CCA are just like single metal aluminum conductors and should therefore be treated in the same manner. The other belief is that at 60 Hz the current in CCA conductors runs mainly in the copper layer, like a “skin effect,” rather than being distributed throughout the entire cross-section of the conductor. This white paper provides evidence that these beliefs are unfounded.