Major work, which will see trenches for huge new wind farms off Norfolk's coast dug across parts of the county, will start later this year.

And preparatory work, which includes road closures and archaeological investigations on the routes where cables will be laid, has already begun.

Three massive wind farms - Swedish energy giant Vattenfall's Norfolk Boreas and Vanguard, plus Danish company Ørsted's Hornsea Three - have got the government go-ahead in recent years.

Eastern Daily Press: Vattenfall has permission for two new wind farms off Norfolk's coastVattenfall has permission for two new wind farms off Norfolk's coast (Image: Rasmus Kortegaard Photography)

READ MORE: Wind turbines, cables and trenches: Is another way possible?

The Hornsea Three scheme will see cables laid in a 35-mile-long trench from Weybourne to Swardeston, south of Norwich, to connect power to the National Grid.

And the cables to carry the power from the Vattenfall schemes will go from Happisburgh to the substation at Necton.

Vattenfall has confirmed the work to dig the trenches for its projects will begin in September, while officials were in Necton recently to explain work which is happening prior to that.

Eastern Daily Press: The sub-station at NectonThe sub-station at Necton (Image: Sonya Duncan)

Work is under way to widen the access from the A47 to the existing access road to the Necton substation, between Necton and Little Fransham.

And, starting in July, a farmers' track close to Spicers Corner will be turned into a new access road to the station, so construction traffic will not go through Necton itself.

That work will reconfigure the A47 and will mean night-time closures on the road for 10 weeks, starting on August 11.

Archaeological investigations are also taking place on 19 sites along the route of where the trenches for cables will be dug.

Eastern Daily Press: Denise Hone, from VattenfallDenise Hone, from Vattenfall (Image: Vattenfall/CHPV)

Denise Hone, stakeholder and community engagement manager at Vattenfall, said: "The onshore construction work is due to begin on September 1 for the cabling which will come in at Happisburgh and connect to the substation at Necton.

"In the meantime, we are completing a number of archaeological investigations at sites, which have now started.

"We have a commitment not to take construction traffic into Necton, so that's why we have work do to on the A47.

"The access road which goes into the substation had a very sharp turn, which is why we needed to widen the road there by making the bellmouth wider.

"And then, in July, there will be work done on a farm track to put in a new road to the substation for construction vehicles to use. There will also be some minor adjustments to reconfigure the A47."

Eastern Daily Press: Cables will run from Happisburgh to Swaffham and from Weybourne to SwardestonCables will run from Happisburgh to Swaffham and from Weybourne to Swardeston (Image: Archant)

She said, once the Vattenfall wind farms are up and running, it will provide enough power for 4.6m homes UK homes.

Ørsted said it has yet to make its final decision on when work will begin on the Hornsea Three scheme.

But preparatory work, including a temporary closure on a section of the High Street in Cawston was carried out in January, which saw the road resurfaced.

And there have been overnight closures of one lane of traffic between Honingham and Easton, near Norwich, as part of the preparatory work for the digging of trenches.

READ MORE: More than 80 Norfolk parishes protest against wind farm plans

Eastern Daily Press: Preparatory work for major work connected to wind farms is under wayPreparatory work for major work connected to wind farms is under way (Image: © Ben Barden Photography Ltd.)

A spokesperson for Hornsea 3, said: "We haven't yet taken our Final Investment Decision (FID), but we remain committed to doing all we can to reach FID on Hornsea 3.

"As we work towards this, we are continuing to prepare for construction through enabling works, including road improvements, preparation of our construction compounds and ongoing engagement with the local community.

"The plans and timeline for the larger scale works are to be confirmed once we get to FID."

The offshore wind farms have caused controversy among communities which will be affected by the work.

Scores of parish councils had urged the government to refuse planning consent.