Imagine that the lifeblood of our modern civilization—electricity—is carried by unobstructed, metal “highways” traversing mountains and rivers. These are bare conductor, wires with no insulation layer on their surface, directly exposed to the air. Typically made of aluminum or aluminum alloys, they boast a conductivity of up to 61% IACS (International Annealed Copper Standard). Due to their superior conductivity and cost-effectiveness, they form the backbone of the global high-voltage transmission network. According to the International Electrotechnical Commission (IEC) standard 61089, the cross-sectional area of these conductors ranges from 50 square millimeters to 1000 square millimeters, capable of transmitting currents up to thousands of amperes with an efficiency exceeding 99%, making them one of the most cost-effective choices in the power industry.
The core reason why power networks favor bare conductors lies in their remarkable economy and reliability. In overhead transmission lines at voltage levels of 110 kV and above, bare conductors account for over 95% of the total, reducing the cost per kilometer by 40% to 60% compared to insulated conductors of the same capacity. A report published by the Electric Power Research Institute (EPR) indicates that using typical bare conductors like aluminum steel-cored stranded wire (ACSR) offers a lifespan exceeding 50 years, a mean time between failures (MTBF) exceeding 100,000 hours, and requires extremely low routine maintenance, primarily consisting of approximately two drone-based line inspections per year. This reduces grid operators’ annual maintenance budgets by about 30%, allowing them to allocate more resources to intelligent upgrades. For example, in the 2022 European grid integration project, the widespread use of bare conductors kept transmission losses across the entire transnational interconnection network consistently below 2.5%, saving an annual power equivalent to the output of an 800,000-kilowatt power plant.
So, where are these powerful bare conductors specifically deployed? They are the absolute protagonists in almost all high-voltage and ultra-high-voltage transmission corridors. In China’s ±1100 kV Changji-Guquan ultra-high-voltage direct current (UHVDC) project, the 3293-kilometer-long line primarily relies on large-section bare conductors, with a transmission capacity of up to 12 million kilowatts, sufficient to meet the electricity needs of 50 million households. On the outskirts of cities, electricity from power plants is transmitted to substations at near the speed of light via 220 kV or 500 kV overhead lines and bare conductors. Even at the ends of the distribution network, 10 kV overhead lines extensively use aluminum stranded wire with a cross-sectional area of approximately 120 square millimeters, carrying a current of about 400 amperes, directly powering towns and industrial areas. In 2021, India used bare conductors for approximately 85% of the 200,000 kilometers of new lines added to achieve rural electrification, successfully reducing access costs by 25% and benefiting over 30 million people.
Despite its seemingly simple structure, the materials science and installation technology of bare conductors are constantly evolving. To cope with high salt spray corrosion in coastal areas, new aluminum-magnesium-silicon rare-earth alloy conductors have reduced the corrosion rate by 70% and extended their lifespan by 20 years. In heavy icing areas, conductors need to withstand ice thicknesses of up to 30 mm, and their tensile strength has been increased to 1800 MPa. With the integration of renewable energy into the grid, smart grid systems monitor the operating temperature of bare conductors in real time. Through dynamic capacity expansion technology, the safe current-carrying capacity of traditional conductors can be increased by 20% under conditions of ambient temperature of 30°C and wind speed of 2 m/s, maximizing the utilization of existing assets. As the International Energy Agency pointed out in its “Grid Outlook 2023,” digitally transforming traditional bare conductor networks is one of the most cost-effective strategies to address the challenge of a projected 50% increase in global electricity demand over the next decade, with an expected return on investment of 7:1. From the Gobi Desert to towering mountains, these silent metal wires are the most fundamental and powerful veins illuminating our era.