The ESB said it planned to spend £2.1bn on overhauling its power network over the next five years.
The investment programme, which includes doubling the number of 110kV substations will provide for the connection of 320,000 new customers, and 19,000 commercial and industrial customers.
The head of the ESB's networks, Dermot Byrne, said the plan was the largest non governmental investment in infrastructure in the history of the State.
Mr Byrne said the company 'intend to deliver a world class infrastructure with value for money for customers, ensuring the highest possible standards of reliability and quality.'
Ireland began freeing up its electricity market in February last year, but it has seen the demands of a booming economy push its power network close to capacity.
With the growing economy fuelled by the energy consuming high-tech sector, the Government was fearful an electricity shortfall would curb foreign investment.
The company said it would also refurbish thousands of electricity poles and thousands of kilometres of electricity lines throughout rural Ireland.
ESB Networks provides lines and substations to serve all customers, irrespective of which supplier they use in the deregulated market, Mr Byrne said.
