Work will start on November 3rd on the laying of an underwater electricity cable connecting Kilpaddoge and Moneypoint stations.
The cable laying vessel arrived in the Shannon Estuary at the weekend and preparatory work is now underway.
The work will take about eight weeks to complete.
Eirgrid, which is overseeing the project, says the laying of the cable represents a significant investment that will ensure a secure energy supply for the southwest region.
The works involves the laying of about 3km of High Voltage Alternate Current (HVAC) 220 kV power cable, connecting the opposite banks of the river Shannon.
It will take about eight weeks to complete, depending on tides and weather conditions.
Eirgrid says all efforts will be taken to ensure there is minimal local disruption.
A foreshore licence was granted to ESB Networks in April, which required it to notify a number of stakeholders and relevant local bodies.
The work is being carried out by Pyrsmian, a high voltage subsea cable manufacturer, based in Finland.