ESB Networks - Our Infrastructure

The electricity networks infrastructure is key to the functioning of a modern economy and society.

The electricity system is currently undergoing major change, driven by Ireland’s commitment to source 40% of electricity requirements from renewable sources by 2020. The electricity networks are being adapted to meet this challenge. This requires significant upgrading of the transmission system including the building of some new lines. It  also involves the deployment  of new information technologies and communication systems and will enable customers to be producers as well as consumers of electricity.

Transmission System

The nationwide electricity transmission system allows for the transport of large volumes of electricity from generation stations, including wind farms, to bulk supply points near the main population centres where it interconnects with the distribution system. It also connects  to a number of customer sites that require very large quantities of electricity. There are  interconnections with the transmission system in Northern Ireland and an East – West link  with the transmission system in Britain via undersea cables.

High voltages are required to transport large quantities of electricity over long distances. The transmission system comprises mainly overhead lines operating at 400kV, 220kV and 110kV. Substations with transformers allow for the flow of electricity between voltage levels. See Table 1 for data on the extent of the transmission system owned by ESB .

 Table 1 - Data on the extent of the Transmission System owned by ESB

ESB Networks constructs and maintains the transmission system. Eirgrid, a separate and independent state owned company, manages the power flows on the transmission system including controlling the electricity generated by all the major generation facilities. Eirgrid also plans the development of the system to ensure that the  transmission system is adequate to meet the growing demand for electricity into the future and also to accommodate the increased proportion of electricity that will be provided by renewable sources, mainly wind farms. More information about the operation and development of the Transmission system, including information about specific development projects, can be found on Eirgrid’s website.

Distribution System

The distribution system allows for the flow of electricity from the transmission system to 2.3 million customer premises in Ireland. It comprises networks operating at 110kV in the Dublin area, and nationwide the networks operating at 38kV, 20kV and 10kV and low voltage (LV).

In Ireland, 30% of the population live outside of cities and towns and the relatively scattered and widespread distribution of the rural population in Ireland is reflected in the extent and the characteristics of the distribution system.  Ireland has four times the European average of length of network per capita. The  ratio of overhead lines to underground cables is 6 : 1.  

 Table 2 - Distribution System Statistics

With so much overhead line exposed to weather and other events, there is a significant challenge in maintaining an adequate and  reliable supply in rural areas.  ESB Networks undertook a major refurbishment of the medium voltage (MV) networks  in rural areas  in the period  1996 – 2006,  replacing approximately 40% of the poles and upgrading 50% of the networks form 10kV to 20kV. This programme has made the system more robust against severe weather conditions and also provided a stronger supply  where needed.  Since 2007 there has been further investment in equipment which reduces the impact of faults on customers by restoring supply automatically  or, in some instances,  remotely from control centres. Over 1,500 such devices have been deployed. These investments have led to a substantial improvement in the reliability of electricity supply in rural Ireland.