Table of contents

4.6.4. Replacing overhead lines with underground cables

Elenia is the second largest electricity distribution system operator in Finland. In order to adhere to the outage requirements of Finland’s Electricity Market Act, and to adapt to increasingly frequent and extreme weather events, Elenia is investing substantially in underground cabling. Currently, 41% of the company’s cabling is underground, with a 75 % target for 2028.

comments (0)

Expected climate change impacts in Finland include increased frequency and intensity of precipitation events, storms and snow loads. Furthermore, increasing temperatures are projected to lead to increased growth and age of trees and increased leaf coverage, which can result in hazards for aerial power lines cables. The collapse of power lines causes temporary loss of power to users and additional repair costs for power providers.

comments (0)

Underground cabling allows adapting electricity transmission and distribution systems to climate change since it protects assets from most adverse weather conditions, in particular storms and excessive snow loads. It can alleviate the requirement for further and more frequent investments in transmission infrastructure maintenance and repairs. There are three main approaches: placing cabling in concrete-reinforced troughs, placing the cables in underground tunnels, or directly burying the cables. In Finland, the technique used involves the construction of trenches ranging from around 0.45 m to 1 m depth, with the cabling then buried within the soil layer. The planned investments by Elenia for 2018 are €140 million.

comments (1)

The key success factor for underground cabling is the availability of the correct technology for underground cabling, with regard to installation, monitoring and management. Elenia co-operates with other underground cabling entities such as telecommunications companies to minimise disturbance to populations through digging activities, as well as reducing costs through collaboration. Although underground cabling could be exposed to new climate hazards, in particular from flooding and soil movements related to landslides, so far these risks remain hypothetical. Excavation due to other construction or maintenance activity represents a key risk of damage to installed underground cables. Elenia applies digitisation and GIS technology with the aim of informing excavators as to the location of underground cables. Additional benefits of underground cabling include more secure energy supply, job provision for excavation and installation work, lower visual impact and reduced accident risk (e.g. fires and impact associated with broken or fallen cables).

comments (2)