Why is copper wires considered over aluminum wires

It's all about the reliability of the contact: when a copper wire is properly and securely terminated (and torqued to spec if called for) it is much less likely to fail than aluminum; aluminum wire can and does fail to contact due in part to it's thermal expansion and contraction, and to aluminum's propensity to form a nonconductive skin over time. Aluminum wire connections must be periodically tightened to ensure connectivity and will perform better if installed using the proper conductive lubricant and also if the connection uses AL/CU rated terminals; if not it will eventually loosen due to expansion and contraction and can cause fires due to overheating. Aluminum is less expensive than copper and may be used if the aforementioned cautions are adhered to.

Aluminum wire when heated tends to expand far more than copper. In an electrical connection this expansion / contraction cycling makes connections loosen over time, which is never a good thing where electricity is involved.

It’s vastly easier to make reliable connections with copper wire than when aluminum is employed owing to the inherent natures of the two elements themselves.

The exchange of free electrons, is what current flow is all about. Copper is considered a good conductor of heat and electrons. Better conductors, such as, Silver Gold and Platinum..Cost way to much to be used in most electronics.

Aluminum, although a conductor, doesn’t have as much as copper does in the way of free electrons. Aluminum requires a higher current flow to achieve the same results copper would at a lower current rate.

As a side note, ..Aluminum Wire was once used in houses, for house wiring..Its since been, somewhat illegal to use Aluminum wire, for houses. I think for fire hazard issues.

copper has lower resistance and therefore gives less losses than aluminium. Although aluminium is lighter than copper, to reduce losses in aluminium wires to the same as copper, it would need thicker aluminium wires, so that cancels aluminium’s weight advantage.

Copper bends and stretches more readily than aluminium, so it doesn’t break so easily when its wires get moved around a lot.

Another disadvantage of aluminium is that when exposed to air, it forms an insulating oxide coating which unless scraped off, makes connections unreliable. For very thin aluminium wire, for example when used as a cheap braiding in a coaxial cable, this oxidation can turn the braiding into nothing but a white insulating dust.

Having said all that, there are cases where using much cheaper and more readily available aluminium makes economic sense compared to copper.

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