Reliable electricity distribution

Securing the reliability of electricity supply is the cornerstone of our operations. Our goal – reliable electricity distribution – also represents best possible customer service. We improve our network with a long-term view, to be able to meet the requirements of our customers and the society, both now and in the future.

  • During 2016, our focus was on the customer experience, mainly in terms of the reliability of supply.
  • We installed a total of 4,566 kilometres of cables underground in order to protect our network from adverse weather conditions.
  • We renovated and constructed our electricity network for EUR 238 million.
  • Our reliability of supply rate was 99.98%.
  • With the network improvement projects, ca 30,000 of Caruna's customers got access to a medium-voltage cable network and more reliable electricity distribution.
  • We upgraded our contingency and emergency plans needed in case of network disturbances and exceptional circumstances.

Electricity network in numbers

Network maintenance and development

As Finland’s largest electricity distribution company, Caruna owns over 82,000 kilometres of electricity network. We plan, construct and maintain our network to meet the current and future needs of our customers and the society. We monitor our network 24/7. Our contractors are on stand-by in our network areas, ready to carry out maintenance and repairs in the event of faults.

We monitor our network 24/7.

Caruna is running a ten-year network improvement programme, installing more cables underground to minimise weather damage. We are committed to meeting our statutory targets by 2028, when we will be able to restore the power to our customers within six hours in urban areas and within 36 hours in rural areas. We invest roughly EUR 200 million into our network every year.

Goals for the reliability of supply defined in the Electricity Market Act

Our network improvement programme is guided, in addition to the target level of the security of supply outlined in the legislation, by the network’s age profile and growth, mainly achieved through new network connections and advancements in the society’s basic infrastructure, among other things. The network constructed now must be able to serve the Finnish society for the next 40 to 50 years and reflect the relevant changes in the consumption and production of energy, such as the electrification of traffic and micro production of electricity.

Factors guiding our investments

We make the investments related to the reliability of supply in the order of their customer impact; prioritising those that benefit our customers the most. The actions will first be targeted into areas with the greatest customer density and quantity of distributed electricity. In 2016, we conducted more underground cabling work outside urban areas than before.

The actions will first be targeted into areas with the greatest customer density and quantity of distributed electricity.

We work on our network in large geographical blocks, which allows us to optimise both the related purchases and environmental and technical aspects of the work. Project planning is guided by life cycle costs: even though underground cabling is slightly more expensive at the construction stage compared to the traditional overhead lines, its maintenance and repair costs are lower.

We also improve the reliability of electricity networks by various technical solutions. For instance, we are able to isolate faults and resume power supply to undamaged network sections faster, thanks to circuit networks and network automation. We also manage forest areas in close proximity to power lines.

Caruna’s Asset Management unit is in charge of managing the network assets. 

Read more about asset management

Case: The cabling of a low-voltage network calls for a glimpse into a crystal ball


Before starting to lay electric cables underground, it is important to consider and try to predict the needs of the network 40 years from now. We know, for example, that the low-voltage network of the future will be affected by the increasing popularity of electric cars and solar panels.

Caruna has already laid about 40% of its electricity network underground and in 2018 it will start cabling the low-voltage network that reaches all the way to customers’ homes and workplaces.

To ensure smart solutions, other future needs of the electrical network are also being piloted. A think tank resulted in a so called link cabinet that was first tested in 2015. The cabinet will be placed at the edge of the customer’s plot, and the idea behind it is to combine the customer’s meter reading centre and Caruna’s electricity supply in such a way that the cabinet will facilitate electricity distribution for as many different needs as possible. When building new constructions, the cabinet will also ensure an immediate electricity supply, whereas with the old operations model it takes about two weeks.

“In the future, customers may have their own renewable sources of energy, such as solar panels or even a small wind power station. The link cabinet would act as a connection point between the customer’s internal network and Caruna’s network, and consequently it would allow the use of alternative energy sources for other things too, besides the customer’s own immediate needs,” says Sebastian Ahlnäs, who is leading the project.

This new cabinet could also be used as a charging point for an electric car and in future it may even supply an optical fibre connection, allowing the customer to get their electricity and internet connection from the same source. The solution is currently being developed in collaboration with Aalto University.

“Aalto University stepped in when we wanted to make the cabinet look as pleasing as possible. After all, it will be installed in a visible place on the perimeter of the customer’s plot and it must blend in with the streetscape,” Ahlnäs explains.

Built in an area of 35 detached houses in Hyvinkää, the first pilot was a great success and led to further piloting in 2016 in two new areas, Mustio and Aura. The functionality of a total of 60 link cabinets as part of the underground electricity network are being tested in the pilot areas to find out how best to build a low-voltage network in 2018 and what structure it should have.

Electricity network improvement measures in 2016

In 2016, we continued to make extensive investments into improving the reliability of supply in all our network areas. Renovation of medium voltage networks remained the main focus of our network improvement projects.

In total, we constructed roughly 4,566 km’s worth of small and medium voltage cable networks. The cabling level of the entire network was 40% by the end of 2016. With the network improvement projects, ca 30,000 of Caruna’s customers got access to a medium-voltage cable network and more reliable electricity distribution.

Read more about regional network data

Reliability of supply in 2016

In 2016, our network was spared any major damage caused by storms or heavy snowfall. The storm Rauli in August 2016 was the most significant single factor causing prolonged average fault repair times. Network improvements carried out from 2014 to 2016 decreased the impacts of the storm. Our reliability of electricity supply level remained on the same level as the year before; at 99.98%.

Our reliability of electricity supply level remained on the same level as the year before; at 99.98%.

In 2016, the figure reflecting the frequency of supply interruptions, SAIFI (System Average Interruption Frequency Index), was 1.7. This means that, on average, customers were subjected to less than two supply interruptions during the year. The SAIDI figure (System Average Interruption Duration Index), reflecting the average duration of supply interruptions experienced by customers annually, was 95 minutes.

The key figures also take into account planned supply interruptions. The number of planned supply interruptions has increased because Caruna is running a major network improvement programme, and the commissioning of new network sections results in supply interruptions to customers. We inform our customers of these interruptions in advance.

Read more about key figures

Preparedness for exceptional circumstances

The society is increasingly more dependent on a reliable supply of electricity under all conditions. Interdependencies between critical electricity and IT networks and customers have been analysed, for instance, in a study by the National Emergency Supply Agency.

We strive to guarantee an electricity supply service that is as free as possible from disturbances. In case the supply of electricity is interrupted, Caruna, as the operator of the distribution network, has to inform its customers and the authorities in charge of rescue operations without delay. Customers and the authorities must also be provided with an estimate of the extent and duration of the interruption. The authorities receive the information through the Critical Infrastructure Disruption Control Room Cooperative Group (Krivat in Finnish), a portal used by the authorities and infrastructure organisations critical for the security of supply.

The electricity interruptions map offers our customers up-to-date information about supply interruptions and estimated repair times.

The electricity interruptions map on our website offers our customers up-to-date information about supply interruptions and estimated repair times. The number of customers affected by interruptions in Caruna’s electricity supply is also shown in the electricity outages map on the Finnish Energy website (Energiateollisuus ry). Our customers can also subscribe to the free alert service Caruna Sähkövahti that informs users of outages directly to their mobile phone or e-mail. We also give our customers advice on how to prepare for electricity supply interruptions.

Read more

Caruna has drawn up contingency and an emergency plans for network interruptions and exceptional circumstances, as required by the Electricity Market Act. The contingency plan covers electricity network disturbances under normal conditions, such as interruptions caused by natural phenomena. The emergency plan, in turn, describes how to secure the reliability of electricity supply under emergency law conditions in case of serious external or internal threats. We keep refining these plans and our practices on the basis of experience gained from disturbances and failures.

Preparedness for exceptional circumstances

The contingency and emergency plans required by the Electricity Market Act must be updated regularly. We submitted the most recent updates to the authorities in June 2016. We review our plans four times a year to ensure an appropriate level of continuity management. Caruna’s Network Operations unit is in charge of contingency and emergency plans. The Head of Security ensures the plans are up to date and appropriate reports are submitted to the authorities.

Caruna takes part in contingency and emergency organisation activities organised by the authorities, with the purpose of ensuring collaboration and readiness in all situations.

Read more about our collaboration with the authorities

Security of supply

As the largest distribution network operator in Finland, Caruna is considered a critical company for the security of supply. Security of supply means the ability to handle disturbances and crisis situations with a minimum amount of special arrangements and damage. We are prepared to maintain our ability to supply electricity on the current supply security level even during a longer crisis.

We are prepared to maintain our ability to supply electricity even during a longer crisis.

We took part in five energy security training events coordinated by the authorities in 2016. By investing in the reliability of our electricity network, we ensure the security and reliability of supply, particularly during disturbances caused by the climate.

Read more about our security of supply activities

Case: Caruna prepares for storms and snow-burdened trees by participating in several drills a year

Imagine if electricity, the Internet and mobile phones stopped working, sewers became blocked, radiators stopped heating and no fuel was available at petrol stations. This is a possibility if a storm causes trees to fall onto power lines, or snow-laden branches dip down onto the overhead lines, preventing the distribution of electricity for an extended time.

Caruna is preparing itself for situations like this by compiling preparedness plans and engaging in regular drills. In 2016, Caruna rehearsed their preparedness for disturbances through various cooperation and emergency drills a total of six times. The purpose of these drills is to refine the cooperation between Caruna, the rescue services, teleoperators, contractors, Fingrid and other local electricity network companies, as well as municipalities and the Centres for Economic Development, Transport and the Environment.

“Caruna plays a significant role in our society as a large distributor of electricity and therefore it is important that its emergency response processes are in place and that they have been rehearsed in case of a crisis. Caruna is well-organised and proactive in this area and its level of preparedness is excellent. Many small companies may have just one person in charge of all their emergency preparations,” says secretary of the Alvar Commission of Western Finland from the National Emergency Supply Agency, Petri Jokilahti, who coordinated the Länsi-Myteri drill.

Organised in May, the Länsi-Myteri drill was a typical cooperation exercise. It involved simulating the destruction caused by a storm, such as outages caused by trees that have fallen on electricity cables due to heavy snow burdens and winds of more than 20 metres per second. Jokilahti points out that climate change is causing increasing numbers of heavy low-pressure storms, which is why more storm preparation drills have been organised in the last few years than before.

The main target of the drills is to improve cooperation between the different participants and to boost the recognition of critical actions. In a fierce storm, there must be close cooperation to pinpoint the disturbance quickly, because the standby batteries of base stations only provide electricity for a few hours.

Updates of the situation will be communicated, for example, via the nationwide Krivat system which operates outside the public Internet and mobile telephone network on a fixed broadband platform maintained by the State Security Networks Group. If needed in a crisis, a contact person from the Länsi-Uusimaa Rescue Department can be invited to the Caruna offices to pass on information about the situation to other rescue departments within Caruna’s area.

“During the Länsi-Myteri drill, we discovered that having up-to-date contact information is crucial in disturbances that require a rapid response. Changes in the operating environment and technology emphasise the importance of up-to-date action plans and continuous training,” concludes Jari Ahlstedt, Operation Manager at Caruna and one of the drill planners and coordinators.