400 Kilovolt Network in Helsinki
The construction of a 400 kV network is driven by the city’s growing electricity demand
Electricity consumption in Helsinki is increasing rapidly. This is being driven in particular by the electrification of heating, transport and other activities, as well as the continued development of the city.
At the same time, there is less local electricity generation than before, meaning that an increasing share of Helsinki’s electricity is transmitted from elsewhere in Finland. This creates a growing need to strengthen the transmission capacity of the electricity network.
Helsinki already has a strong and reliable electricity network, but rising electricity demand requires significant investment in the network’s main transmission connections. The aim of these investments is to ensure sufficient electricity transmission capacity well into the future.
Helsinki is home to a number of services and functions that are vital to society, including healthcare, public transport and other critical infrastructure. Developing the network will help strengthen security of supply under all circumstances. This will ensure that both everyday services and critical functions can continue to operate safely and reliably, even during disruptions and exceptional situations.
The 400 kV voltage level will strengthen electricity transmission capacity
At present, Helsinki’s main transmission connections are based primarily on the 110 kV voltage level. To support growing electricity demand in the future, 400 kV connections will also be required alongside the existing network.
The new voltage level will increase transmission capacity and enable larger volumes of electricity to be transferred across the Helsinki region to where they are needed most.
An amendment to the Electricity Market Act, which entered into force at the beginning of 2026, transferred certain network development responsibilities to distribution system operators. As a result of the legislative change, local and regional 400 kV networks now fall within the responsibility of the distribution system operator.
In Helsinki, this means that Helen Electricity Network Ltd is responsible for developing the network from the transmission system connection point towards centres of electricity demand.
The introduction of the new 400 kV voltage level will also change the role of the existing 110 kV network. Going forward, investments will be required at both voltage levels to ensure that the electricity system can meet future transmission needs.
Electricity consumption growth forecast
| Year | Actuals | Forecast |
| 1910 | 1.00 | 0.00 |
| 1915 | 5.00 | 0.00 |
| 1920 | 8.00 | 0.00 |
| 1925 | 14.00 | 0.00 |
| 1930 | 23.00 | 0.00 |
| 1935 | 25.00 | 0.00 |
| 1940 | 34.00 | 0.00 |
| 1945 | 51.00 | 0.00 |
| 1950 | 58.00 | 0.00 |
| 1955 | 105.00 | 0.00 |
| 1960 | 154.00 | 0.00 |
| 1965 | 218.00 | 0.00 |
| 1970 | 312.00 | 0.00 |
| 1975 | 375.00 | 0.00 |
| 1980 | 444.00 | 0.00 |
| 1985 | 572.00 | 0.00 |
| 1990 | 630.00 | 0.00 |
| 1995 | 647.00 | 0.00 |
| 2000 | 702.00 | 0.00 |
| 2005 | 759.00 | 0.00 |
| 2010 | 813.00 | 0.00 |
| 2015 | 766.00 | 0.00 |
| 2020 | 734.00 | 0.00 |
| 2025 | 987.00 | 0.00 |
| 2030 | 0.00 | 1460 |
| 2035 | 0.00 | 1620 |
Connection Between Sörnäinen and Vanhakaupunki
New electricity transmission structures are being planned for Helsinki
- New Cable Tunnel Between Vanhakaupunki and Sörnäinen
A cable tunnel of approximately 4.2 kilometres is being planned between Vanhakaupunki and Sörnäinen. The tunnel solution was chosen because there is not enough space for 400 kilovolt transmission lines within the current street structures.
- New 400/110 kV Substation in the Hanasaari Area
A new Sörnäinen 400/110 kilovolt substation is planned for the Hanasaari energy block area. The new substation will strengthen electricity transmission capacity and secure the area’s future energy needs.
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FAQ
Electricity consumption in Helsinki is growing rapidly, and the ongoing electrification of society requires increasingly efficient electricity transmission connections. The 400 kV voltage level will enable a reliable and sufficient supply of electricity to a growing urban area while supporting the city’s long-term vitality.
In Helsinki, the aim is to deliver the network largely underground. The project planning process includes assessments of environmental, ecological and land-use impacts, while solutions are developed in close alignment with the objectives of public authorities and urban planning.