The ESB has raised over $1 billion from investors in the United States that will be used to upgrade its existing network.
Announcing details of the deal this morning, the ESB said it has also secured an additional $500 million from a consortium of banks.
The company says the money will be used to fund its refurbishment programme which it is costing €3 million a day.
The deal is believed to be the second largest fund-raising undertaken to date in the New York private placement market where companies raise money by selling their bonds directly to investors.
Bonds issued through private placements are not subject to the same level of regulation as traded investments such as stocks and shares.
US reports indicated at the end of last month that the ESB has managed to raise $1 billion in a deal arranged by two leading banks, ABN Amro and Barclays Capital.
A target of $300 million was set for the fund-raising originally, but US sources told the Irish Timesat the time that a "frenzy" of interest among investors prompted the banks involved to arrange another $700 million.
About 27 investors are believed to have participated in the deal, some from the United States and others from Britain.
The level of debt at the ESB has been growing in recent years. The company had debts of €632 million in 2001, but this rose to €902 million last year - a 43 per cent increase.