National Rules for Electrical Installations

The highest transmission voltage on the interconnection between the Republic of Ireland and Northern Ireland is 400 kilovolts. This high-voltage transmission line runs for approximately 85 kilometers (53 miles) between two substations - the Woodland substation in County Meath in the Republic of Ireland, and the Trewmount substation in County Tyrone in Northern Ireland. The line has a capacity of 500 megawatts.