Mr. Fintan Slye:

In order to use the capacity that is there to transfer power, either South to North or North to South, we need to have two circuits so that the loss of one will not damage the integrity and reliability of the system. It is called the N minus 1, N-1, principle. The transmission system and the power grids around the world are operated so that no one thing, no matter what it is, should take down or damage supply to the grid. It is a fairly basic principle. The situations outlined by the Deputy in terms of Coolkeeragh, Moyle and all of those issues have been analysed in the generation adequacy report. Under all of the reasonable scenarios around those issues, the security supply margin in Northern Ireland becomes inadequate at the end of the decade and needs to be addressed. Security supply is incredibly important to business, industry and the economy. Hence, reliance on the single line between North and South is limited by the fact that it is a single line and any one thing could potentially take it out of commission.