Contrary to some claims it is not common practice to underground high voltage transmission circuits in Europe, or indeed in the rest of the world.

It is generally accepted that undergrounding high voltage transmission lines is significantly more expensive than building overhead lines resulting in increased electricity prices for customers.

It is intended that the planning application for the Tyrone to Cavan Interconnector will be for an overhead line but a full assessment of underground options will be submitted for consideration.

Northern Ireland Electricity and Eirgrid have commissioned several reports on undergrounding transmission lines in the Irish electricity network. These reports focus on the practicality, costs and technical feasibility of placing the Interconnector underground. They also examine the potential of placing long lengths of transmission circuitry underground and the feasibility of using Direct Current (DC) technology in the Irish network.