Start of construction on the underground cable from Uznach to Tuggen

14.09.2023 - To secure future energy supply, Axpo is increasing the operating voltage of its power lines in the region south of Lake Zurich from 50 to 110 kilovolts. As part of this project, the existing line between Grynau substation in Uznach and the municipality of Tuggen will be laid underground. The construction works started in mid-September. 

The high-voltage grid on the west side of Lake Zurich ensures the energy supply for the surrounding communities. For a reliable and sustainable energy supply, Axpo is increasing the operating voltage of its lines in this region from 50 to 110 kilovolts (kV). This will see transmission capacities increased and transmission losses reduced. As part of the voltage conversion project, among other things, Axpo is installing a new 110-kV underground cable between the Axpo Grynau substation in Uznach and the municipality of Tuggen. 

Route

In Tuggen, the new underground line follows the Mülibach canal and the municipal roads eastwards to the Wildbach canal. Thereafter, the conduit block runs parallel to the Mülibach canal northwards to the Tuggen motorway exit. The line will pass under the A15 in Tuggen before running eastwards parallel to cantonal road (main road) to the Grynau substation. The line will be installed primarily using civil engineering with an open-trench method or flush drilling.

The 110-kV-cable conduit block will be laid alongside empty conduits of the Tuggen electricity utility and Axpo in certain sections of the pipeline route. These will be used for the regional distribution grid and the subsequent, partial underground installation of 16-kV lines. 

This route was chosen in close consultation with the relevant authorities and various interest groups. The Swiss Federal Inspectorate for Heavy Current Installations (ESTI) granted planning permission for the 7.2-km-long underground cable in April 2023.

Decommissioning of the overhead line

The construction works started on 12 September 2023. The voltage conversion will take place in two stages in 2025 and 2027 due to its dependency on an additional con-version project. The now obsolete 50-kV overhead line section between Uznach and Schübelbach will be dismantled following the full voltage conversion and on completion of all measures in the region to the south of Lake Zurich.

Voltage conversion

Axpo is gradually converting its existing transregional distribution grid from operating at 50 kV to 110 kV. This will allow more electricity to be transported and grid losses to be reduced by up to 75 per cent. The voltage conversion is making an important con-tribution to environmentally friendly and efficient grid operation in this regard. The voltage conversion will eliminate bottlenecks and accommodate increasing energy de-mand. A powerful and efficient electricity grid is a crucial prerequisite for reliably high and sustainable security of supply for the entirety of north-east Switzerland, including in the future.