The two transmission system operators started commercial trial operations of the cable on Oct. 1 at a capacity of 700 megawatts (MW) in both directions.

The cable's full capacity is 1,400 MW, enough to power around 1.4 million homes, and is intended to provide Britain access to Norway's hydropower resources to help balance intermittent wind power, while Norway can import power during times of high wind to save water in reservoirs.

"Changes in capacity will take place during the trial period, before we can put the cable into ordinary operation," Peer Olav Oestli, head of system operations at Statnett, said in a statement.

However, an error on the British end of the cable is currently restricting actual available capacity to 700 MW, Statnett added.

Pole 1 of the connection is out of operation and the end time is still uncertain, a separate market message posted by Statnett showed.

($1 = 0.8743 euros)

(Reporting by Nora Buli)