From the wire and cable "in aluminum to copper" phenomenon

For the wire and cable industry, the most obvious material substitution is to use aluminum conductors instead of copper conductors. When conducting the relative costs of copper and aluminum conductors, factors such as price, specific gravity, and electrical conductivity need to be considered in order to determine whether the use of aluminum conductors is a true answer to cost savings. Copper is heavier than aluminum. The specific gravity of copper is 8.9g. In cm3, the specific gravity of aluminum is 2.7 g/cm3, that is, in the case of the same conductor size, the weight of the copper conductor is 3.3 times that of the aluminum conductor. However, the conductivity of aluminum is only 61% of that of copper, that is, in the case of the same transmission current, the cross section of the aluminum conductor is 61% larger than that of the copper conductor. Therefore, in terms of the weight of the conductor, to make the two conductors have the same current carrying capacity, the weight of the copper conductor required is approximately twice that of the aluminum conductor. In addition, the price ratio of copper to aluminum is about 3.5, so the cost of the equivalent copper conductor is 7 times that of the aluminum conductor.

Of course, the simple cost comparison described above does not explain all the problems. Since the cable product is a product with a standard conductor size limit, it is impossible to purchase an aluminum core cable whose conductivity is exactly equal to that of the copper core cable. Therefore, if you use aluminum conductors to make cables, you must use larger aluminum conductors. Experience has shown that in the case of equal current carrying capacity, the conductor cross section of the aluminum core cable should be twice that of the copper core conductor. Since the cross section of the aluminum core cable conductor is twice that of the copper core conductor, the subsequent increase in the insulation, sheathing, and armoring of the aluminum core cable weakens the price advantage of using the aluminum conductor. This means that the price advantage of aluminum and copper is not significant because the conductor is only a small part of the cost of the entire cable.

Taking a 70mm2 copper core cable as an example, the cost of the copper conductor accounts for about 65% of the total cable cost, while the 120mm2 aluminum core cable with the same ampacity cost can save 23.5%. If the cost of the copper conductor accounts for 80% of the total cable cost, then the cost savings of the aluminum core cable with equal current carrying capacity can reach 46%. The aluminum core cable loses its cost advantage only if the cost of the copper conductor in the cable falls below 50% of the total cable cost. Now, the cost of most copper core low voltage cables and many medium voltage cable conductors has exceeded 50%. Therefore, compared with copper core power cables, the cost saving advantages of aluminum core power cables are quite obvious.