Underground installation

The electricity is transmitted by means of overhead cables and cable lines, i.e. over or under the ground. Overhead cable lines are a considerably cheaper option for high voltages. A further advantage is that faults can be located and repaired more quickly. However, the susceptibility to interference due to weather phenomena like lightning and storms is significantly higher in the case of overhead cable lines. This does not, however, have consequences for customers because of circular grid operation. In comparison cable lines are better protected against outside influences. However, if repairs are necessary they tend to be more expensive and take more time.

Which techniques are used in which situations, depends on a number of factors. The lower the voltage, the more frequently cable lines are used. Around 80 per cent of low and medium voltage grids consist of underground cables, while in contrast only around one percent of high voltage grids are located under the ground. The much higher costs of cable lines, which would barely be affordable for longer transmission routes, are not the only reason for this. At the highest voltage levels, cable lines need additional components, which are technically complex.

In choosing the right kind of line, the preservation of the countryside is becoming increasingly important. A compromise between the wishes of the population, who feel disturbed by electricity pylons and commercial and technical demands is always required. In the future too, overhead cable lines will be irreplaceable for the transport of larger quantities of electricity. On the other hand, cable lines are increasingly being used for local distribution at lower voltage levels in Switzerland.