North-South electricity interconnector: 200 attend hearing in Carrickmacross
More than 200 people are attending a hearing into plans to build a north-south electricity interconnector.
The plan is to connect the two grids using 138km of overhead lines between a new substation near Moy in County Tyrone and County Meath.
EirGird, the company behind the proposal, has said the interconnector is essential to secure a reliable supply into the future.
It is the second oral hearing by An Bord Pleanála into the matter.
An Bord Pleanála, the Irish planning authority, will hear submissions from EirGrid and opponents to the plans, at the hearing in Carrickmacross, County Monaghan.
It is due to last three months.
The first hearing collapsed in 2010 after hearing testimony for several weeks.
Under the proposals, 299 pylons would be constructed over the 103km route between the border at Clontibret in Monaghan and a large substation in Batterstown, County Meath.
The pylons would vary in height between 26m and 51m across Monaghan, Cavan and Meath.
A lawyer for EirGrid told the hearing that the project was essential to secure a safe, reliable, economic and efficient electricity supply between the Republic of Ireland and Northern Ireland.
He said the development would save 20m euros (£15.47m) annually by 2020 rising to 60m euros (£46.42m) by 2030.
Campaigners want the cables to be put underground for environmental and health reasons.
The lawyer for EirGrid said the company had looked at the possibility of installing high voltage cables underground but said the best technical solution was to keep the cables over ground for the whole duration of the route.
In the Republic of Ireland, the state-owned commercial energy company, EirGrid, has submitted plans for the southern half of the project.
In Northern Ireland, the lead is being taken by System Operator for Northern Ireland (SONI).
A separate planning application is before the Planning Appeals Commission, with a hearing due to begin on 21 June.