My house, from the 1970s, has 100% aluminum wiring. I bought special connectors to connect copper wires to aluminum wires for extra safety when I put new outlets and switches in, as there is a fire concern when the connections are not done properly.
The cause is that over time, aluminium joints become higher and higher resistance, and get hotter and hotter till one day they fail.
There is some special gunge stuff you can get to put in each joint which supposedly stops this happening. But personally I don't trust the gunge to keep working for the 100+ years the wiring might remain in use.
Particularly if there is a water leak and the gunge is washed away - and then your 10 year timer starts ticking till a deadly fire.
They're cheaper than pure copper, and the plating means they don't have the fire problem - since it is always the copper surface that makes contact in any joint.
I don't know why we don't use them - they would make electrical jobs cheaper, and mean we can afford to upgrade in other ways - like for example having every circuit powerful enough for a dryer rather than needing a special dryer circuit.
Basically, both copper and aluminum are "rust-proof" because they develop a thin, hard layer of oxide immediately upon exposure to air. However, this also means that when a new crack forms (by vibration of the wiring or thermal expansion for example) that crack will be immediately coated by an oxide layer. At the same time, moisture in the air will create a galvanic cell with the copper as cathode and aluminum as anode (because aluminum is more active, more willing to give up electrons, which is because its bond with its electrons is weaker than copper's.) As the electrons leave the aluminum it develops a positive charge, which attracts negatively charged oxygen.
It is this last effect, galvanic corrosion, which I believe to be the chief issue with CCA wiring. Copper and stainless steel, for example, are much closer in the galvanic series than copper and aluminum, so copper and aluminum corrodes significantly faster.
Unfortunately, galvanic corrosion is a tough one, because lots of modern American houses are built with poor ventilation - as you can see by the large number of homes with mold issues. That moisture is exactly what enables galvanic corrosion. I think if we used CCA wiring across America we'd see a number of house fires caused by moisture -> corrosion -> higher resistance -> heat -> fire.
It seems like if we want to achieve the goal you mention, we could switch over to 240v like much of the rest of the world.
US residential has 240v at the home fuse box from the upstream 3-phase.
But I imagine it'd require a big adjustment at the utility level if everyone started drawing from +120v & -120v, instead of the current balance around the neutral.
NEC 2020 edition, Article 334 Non-Metallic Sheathed Cable
334.104 Conductors.
The 600-volt insulated power conductors shall be sizes 14 AWG through 2 AWG copper conductors or sizes 12 AWG through 2 AWG aluminum or copper-clad aluminum conductors.
More dual amp/dual volt wiring devices: https://www.plugsocketmuseum.nl/NorthAm1combi.html
Wouldn't that eventually cause mechanical adherence issues with dissimilar metal plating?
but they can be caught early using a cheap $45 IR camera from E-Bay/Amazon. I caught one early and a retightened of a wirenut is all that is needed.
But to go up to 2020 NEC code, you must replace all wirenuts with the purple Alumniconn lug strip.
Purple wirenut is now not to code for permanent jobs; only temporary. For that, all future wiring jobs must be redone with Alumniconn lug strip and tightened to 15 lb/ft
One is $48
https://m.aliexpress.us/item/3256805363165906.html?spm=a2g0n...
https://www.amazon.com/4%C2%B0F-752%C2%B0F-Accuracy-Infrared...