Britain’s National Grid is routinely restricting the use of its own power cables from the Continent because of the risk of blackouts if they failed.
Britain’s electricity system is sufficiently fragile at certain times of day that if one of the subsea “interconnectors” tripped while importing at full capacity, it could trigger power cuts like those of August 9.
A senior National Grid source told The Times that for several years it had been managing this risk by limiting the use of the cables at these times, especially overnight, so as to reduce the size of the potential supply shock.
They said that the costs of doing so, which are understood to run to many millions of pounds, were cheaper than paying for enough back-up to withstand a potential failure.
The disclosure of the arrangement, described by one analyst as “perverse”, raises questions over how National Grid manages supplies and over its plans to spend billions of pounds building more interconnectors.