PUTTING KEY parts of the electricity network underground will increase the risk of power cuts, according to experts who recently completed a Government report.

German consultancy Ecofys told members of the Oireachtas Committee on Communications, Energy and Natural Resources that underground transmission cables were not suitable for use as part of the national electricity grid as the technology was not sufficiently well developed.

The committee is reviewing plays by national grid operator Eirgrid to build two lines - a total of 65km - linking Meath with Tyrone.

The high-capacity lines will form part of the national grid, and are designed to secure power supplies for the northeast.

Ecofys consultant Dr Karsten Burgess told the committee that underground cables carry a higher risk of breakdown than overhead power lines, and he pointed out that where there were problems they took longer to repair.

Dr Burgess told the committee that where a breakdown takes days rather than hours to repair, this will lead to problems in the electricity transmission system.

In a letter to the Department of Communications, Marine and Natural Resources, Dr Burgess said that underground cables were 10 times more likely to break down than overhead lines.

"Currently, underground cables do not, therefore, compare to overhead lines in terms of adequacy of the electricity transmission system and in terms of reliability and security of supply."

Dr Burgess reiterated these points to the committee yesterday, and pointed out that where high-capacity power lines were placed underground in other countries they do not form part of the national grid.