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. Construction work is planned on 54 of a total of 142 pylons: 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.
The planned construction measures to increase the voltage of the Bassecourt – Mühleberg line can be technically implemented in a short period of time (approx. 12 months).
The construction costs for the increase in voltage and modernisation of the Bassecourt – Mühleberg extra-high-voltage line amount to approximately 11 million Swiss francs.
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.
The planned construction measures for the voltage increase are expected to start in 2022 and last around one year. Swissgrid will carry out the construction activities in two stages. The line between Pieterlen and Bassecourt will be upgraded between autumn and winter 2022. The construction activities between Mühleberg and Pieterlen will take place in the spring and summer of 2023. Swissgrid is planning to increase the volt-age in the existing extra-high-voltage line between Bassecourt and Mühleberg from its current 220 kilovolts to 380 kilovolts in the autumn of 2023.