Switzerland’s power grid comprises over 250,000 kilometers of lines. Composed of a transmission and a distribution network, the voltage is gradually reduced from 380,000 to 230 volts enroute to the consumer. The aboveground transmission network, some sections of which are more than 40 years old, measures 6,700 kilometers. As it is designed for considerably smaller amounts of electricity from predominantly central power stations, it only partially satisfies today’s needs. Nowadays, considerably larger quantities of electricity are transported, and an increasing number of decentralized (small-scale) power stations feed electricity obtained from renewable energy into the grid. The power lines are, therefore, becoming increasingly overloaded and getting hotter and hotter. As Switzerland’s overhead high-voltage power lines are almost exclusively made of aluminum alloy while those in neighboring countries are usually composed of pure aluminum and a steel core as interconductors, international research results can only be applied to local conditions to a limited extent. In other words, national research is necessary.