- Rannikkolinja (Coastal Line; from Turku to Keminmaa)
- Jokilinja (River Line; from Helsinki via Kangasala and Alajärvi to Oulu)
- Järvilinja (Lake Line; from Lappeenranta to Oulu)
- Metsälinja (Forest Line; future connection from Petäjävesi to Oulu).
In addition to these, the 400/220-kilovolt connection from Oulu to the Norwegian border has been named Tunturilinja (Fell Line).
The Finnish main grid was born when a high-voltage line between Imatra and Turku was constructed at the end of the 1920s. This connection is now being renewed and, with respect to tradition, the new line will be called Rautarouva II (Iron Lady II).