Haute-Savoie: technicians repair a very high voltage line struck by lightning

On the cliffs of Sixt-Fer-à-Cheval (Haute-Savoie), in the heart of the Alps, a titanic project awaits technicians: the repair of a very high voltage line which connects France to Switzerland. To get to the area, the team takes the air. There is no land access around the pylon. At an altitude of 2,000 meters, a storm damaged the line. Lightning struck and caused damage that needed to be repaired as quickly as possible. “The harness position is not enough for us. We also need support on the shoulders if we fall over,” explains a technician.

Using a nacelle, the material is transported to the top of the 40 meter high pylon. The roped men climb with the strength of their arms. The electricity was cut off for the duration of the work, with no consequences for the network. Then begins a balancing act for the linemen, the name given to these technicians. Space is cramped. On the ground, a colleague is responsible for piloting the basket. The intervention “was detected approximately 600 meters away,” explains Patrick Dumoulin, RTE works manager.

An operation to prevent short circuits and power outages

800 meters above the void, technicians arrive at the impact of lightning. This broke part of the metal strands which carry electricity. The structure has become fragile. The linemen first apply tape to the cable. Then comes the crucial step: wrapping these new sturdy metal strands all around the cable to reinforce it. “Our operation is essential to avoid short circuits and power cuts,” indicates an RTE lineman.

With global warming, storms, heatwaves and storms are more severe. So, 24 billion euros were invested over 15 years to adapt the network. “We continue to develop new products, to strengthen them precisely so that they can ultimately withstand temperature increases in 2040 and 2050,” says François Contensous, director of the RTE Savoie and Haute-Savoie maintenance group. Extreme heat waves generate additional costs of 1.7 billion euros to adapt electricity infrastructure.