SSEN Transmission says work to construct 12km of overhead power lines from Kergord to Gremista is set to get under way.
Principal contractors Norpower are set to begin installing the new power lines this week, starting south of Sandwater.
The overhead lines will link in to two sections of underground cables at each end, helping to complete the connection to mainland power grid for the first time.
Around 22km of cables are being connected between the Gremista Grid Supply Point and the Kergord substation, with a combination overhead lines and underground cabling.
Materials have been delivered to site via helicopter in recent weeks, SSEN said.
SSEN Transmission lead project manager Grant Smith said the initial underground cabling work was “off to a good start”.
Scottish government ministers approved the project in May, despite residents in the Tingwall, Whiteness and Weisdale area fiercely opposing the plans.
They had said they would be left living in a “forest of poles”, and Tingwall, Whiteness and Weisdale community council chairman Andrew Archer said in May they would be “an eyesore”.