However, equipment used in cabling, such as cable joints and terminations, is naturally exposed to ground stresses, moisture conditions and potential environmental impacts that change over time. Therefore, high-quality and durable underground cable accessories and their meticulous installation play a very important role in the functionality, durability and safety of the electricity network.
Distribution system operator Kokemäen Sähkö, operating in Western Finland, emphasizes the use of high-quality and durable underground cable accessories in the construction of the electricity network and the importance of installation carried out accurately and flawlessly.
Kokemäen Sähkö builds approximately 10–15 kilometers of 20 kV underground cable network annually and has been using Ensto's cold shrink accessories for jointing and terminating cables for more than a decade. The accessories have proven to be very reliable together with correct installation and have contributed to improving the stability of network operations and reducing maintenance needs.
Aiming for the Best and Most Sustainable End Result
Cold shrink accessories have also significantly facilitated and accelerated installation work, as they reduce the need for hot work and the number of components to be installed. Geometric stress control components are pre-installed already at the manufacturing stage, which makes work simpler and more efficient on site.
The attitude of meticulous and high-quality installation is reflected in Kokemäen Sähkö's operations in every way: "If a tent is needed to protect the installation and it takes half an hour extra time, it is done to ensure good and careful installation. Although cold shrinks speed up installation, the most important thing is flawless installation, which will last for decades in the electricity network," tells Eero Turto, Network Manager at Kokemäen Sähkö.
Despite all the good advantages of a cold shrink, the installation of an underground cable joint or termination still requires special care. Installation includes important measurement steps and component parts that must be installed according to installation instructions. By taking care of every detail in the installation, the best and most durable result can be achieved. Even minor installation errors can shorten the life of the network or reduce its reliability.
Over the past ten years, Kokemäen Sähkö has had exactly one fault caused by the underground cable network. The low number of network faults is reflected in the security of electricity supply to customers, which is more than 99%.
"Repairing the underground cable network is laborious – in the event of a fault, locating it may take a long time, after which the cable still needs to be dug out and repaired. If this can be prevented, it’s worthwhile to invest in the installation process and ensure it is carried out with exceptional care," Turto emphasizes.
In terms of reliability, it is important not only to install and use cold shrink accessories, but also to choose the right accessories for the right application. Thorough network design, discussions with the supplier, practical experience and insights of installers to help find the best and most cost-effective solution play a key role in this selection.
Installer Certification Adds Quality to Installation
Kokemäen Sähkö's installers completed Ensto's installer certification for the first time in 2018, and the renewal certification was carried out in summer 2024. Installer certification means a demonstration test of the installation of underground cable accessories, aiming for proper installation. The starting point for the certification has been the need for DSOs to reduce fault interruptions caused by installation errors. As an additional benefit, Ensto grants an additional three-year warranty for joints and terminations implemented by certified installers.
Installer certification is seen as an important way to ensure installation quality objectives and reduce the risk of defects caused by installations. The company also values the continuity of training and the regular renewal of certification. The certification is updated every five years, during which time installers are required to carry out retests.
"Continuous competence assessment is important for installers, as it not only strengthens their professional competence, but also maintains a high-quality level of installation, which in turn has a positive effect on both the smoothness and safety of work," emphasizes Pekka Mäkivirta, Area and Procurement Manager at Kokemäen Sähkö.
"We are a small distribution system operator, and we independently handle all network-related tasks, such as network design, operation, installation and maintenance. We are responsible to our customers, and our goal is to provide as reliable electricity distribution as possible without interruptions, Mäkivirta continues.
Kokemäen Sähkö in Brief
Kokemäen Sähkö operates in Western Finland, serving around 5,800 customers. Its offerings include electricity transmission, sales, as well as related services. Kokemäen Sähkö maintains strong electricity supply security and cost-efficiency by working closely with distribution network operators in neighboring towns and by being part of Satapirkan Sähkö Oy, a joint venture owned by nine energy companies.
