In the world of electrical materials, copper has long reigned supreme as the king of conductivity, with its internationally annealed copper standard conductivity defined as 100% IACS. However, when we turn our attention to aluminum, we find that its aluminum electrical conductivity is approximately 61% IACS. This means that, for the same size and temperature, aluminum’s conductivity is about 60% that of copper. This key difference in physical parameters directly results in aluminum conductors needing approximately 61% of the cross-sectional area of copper conductors to achieve an equivalent resistance value when carrying the same current. For example, a copper wire with a cross-sectional area of 10 square millimeters would require approximately 16 square millimeters of wire to achieve a similar current-carrying capacity if made of aluminum.
However, conductivity is not the only determining factor in material selection. Density and cost constitute aluminum’s core competitive advantage. Aluminum’s density is only 2.7 g/cm³, about 30% of copper’s density of 8.96 g/cm³. This means that, for the same length and resistance value, an aluminum conductor can be about 50% lighter than a copper conductor. This characteristic is crucial in high-voltage overhead transmission lines. For example, the State Grid Corporation of China extensively used high-strength steel-cored aluminum stranded wire in the 3284-kilometer-long Changji-Guquan ±1100 kV UHVDC project, whose significant lightweight advantage reduced tower structure load and construction costs by approximately 15%. From a price volatility perspective, historical data from the London Metal Exchange shows that aluminum prices are typically only 30% to 40% of copper prices. This huge cost difference allows for savings of up to 60% in raw material procurement budgets when using aluminum conductors in large-scale projects.
However, aluminum exhibits another characteristic in specific scenarios involving high-frequency currents. Due to the skin effect, high-frequency currents are primarily concentrated on the conductor’s surface. In this case, the treatment and geometry of the surface oxide layer become more critical than volumetric conductivity. Precision-surface-treated aluminum alloys are used in 5G base station RF components or large data center busbars. Although their aluminum electrical conductivity is lower than copper, AC resistance can be effectively controlled through optimized design (e.g., using tubular or special finned structures to increase surface area). A technical report published by the Institute of Electrical Manufacturers (IEM) indicates that at 60Hz power frequencies, to achieve the same current-carrying capacity as 1000kcmil copper cable, aluminum cable would need to be expanded to approximately 1600kcmil, while still maintaining a cost advantage of about 35%.
The reliability of connection technology and the mechanical properties of materials are the technical barriers that must be overcome when aluminum replaces copper. Aluminum conductors are prone to forming a high-resistivity oxide film at the contact points and have a greater tendency for creep, which may lead to electrical connection failures. However, these problems have been effectively overcome by adopting advanced crimping terminal technology, applying anti-oxidation paste, and specifying strict torque installation procedures. For example, in the residential building wiring sector, the United States has widely used AA-8000 series aluminum alloy cables since the 1960s. Related safety standards have been verified through hundreds of thousands of installations, and its failure rate has been reduced to a level comparable to copper cable systems, i.e., less than 0.1%.
The final application selection is a comprehensive trade-off between performance, cost, and sustainability. In long-distance power transmission where fixed installations and space requirements are not stringent, aluminum dominates due to its lightweight and cost-effectiveness, with approximately 90% of high-voltage transmission lines worldwide using aluminum conductors. In automotive manufacturing, Tesla extensively uses aluminum connectors within its battery packs, balancing conductivity requirements with weight reduction goals within limited space, potentially reducing the weight of wiring harness systems by about 20%. For the extremely compact spaces within consumer electronics and precision instruments, copper remains the preferred choice due to its superior aluminum electrical conductivity and greater mechanical strength. Looking ahead, with continued advancements in alloying technology and surface treatment processes, aluminum’s penetration rate in the electrical field is expected to continue increasing at an average annual growth rate of approximately 2%, particularly in industries highly sensitive to weight and cost, such as green energy and electric vehicles, where aluminum is continuously expanding its conductive applications.