The Bassecourt – Mühleberg extra-high-voltage line is 45 kilometres long and was built in 1978. The Federal Inspectorate for Heavy Current Installations (ESTI) approved the line for an operating voltage of 380 kV back in 1978. However, it has been operated with a voltage of only 220 kV since that time. The voltage increase will take place in compliance with the limits specified in the Ordinance on Protection against Non-Ionising Radiation (NISV).
The line will be modernised along the existing pylons and will not change the landscape. In total, construction work is planned on 56 of 142 pylons as well as on the guyed gantries of the two substations in Pieterlen and Bassecourt: individual pylon foundations will be reinforced, double anchor chains will be installed, or the cable winch tension will be increased. The future operation at 380 kilovolts will result in an increase in noise emissions that will be hardly noticeable.
Swissgrid is investing approximately 17 million Swiss francs in the modernisation of the Bassecourt – Mühleberg line. The voltage increase project is part of the «Strategic Grid 2025», Swissgrid’s long-term grid planning.
On 22 August 2019 the Swiss Federal Office of Energy approved the voltage increase of the extra-high-voltage line between Bassecourt and Mühleberg from 220 to 380 kilovolts and dismissed the objections. These generally related to the load from magnetic fields and the noise or demanded that the line route be relocated or cabled. Various appellants have appealed to the Federal Supreme Court against the decision made by the Swiss Federal Office of Energy. The Federal Supreme Court confirmed the planning approval for increasing the voltage of the Bassecourt – Mühleberg line, rejecting all complaints, on 23 March 2021.