Crews from Northern Ireland, the UK and France will work alongside ESB Networks teams
Efforts are continuing today to restore power and water supplies to tens of thousands of people.
Tens of thousands of people - particularly in the south and south-west - are still affected following Storm Ophelia on Monday.
Today, crews from Northern Ireland, the UK and France are joining ESB Networks staff as part of a mutual aid agreement.
Around 250 staff are being supplied by the other European networks, and they'll be working alongside 3,500 ESB staff & contractors.
More than 300,000 customers have been reconnected so far, while around 70,000 remain without power.
In an update last night, Irish Water said around 25,000 people are without water - down from a peak of 109,000.
The utility company says Cork, Waterford and Wexford are worst affected by the continuing water supply issues.
This morning, Eir said that 50,000 customers are still without broadband, phone and mobile service.
In a statement, they explained: "There are over 1,000 different locations across the country where we have sustained network damage.
"The vast majority of impacted mobile sites are now back in service."
The company adds: "Given the overhead nature of our network in rural areas, the damage is extensive and repair work will take time. Our 1,200 staff will continue to work repair network damage."
The Defence Forces are continuing to assist with repair efforts, with the Air Corps planning to transport ESB crews to islands off the coast today if the weather allows.