While historically a monopoly, the ESB now operates as a commercial semi-state concern in a "liberalised" and competitive market.

By business area, the principal companies are: ESB Networks Limited manages construction and maintenance of the electricity transmission system.

Since 4 April 2011 the Commission for Energy Regulation no longer sets the company's prices; the trade-off for this was that the division was required to change its name from ESB to Electric Ireland, to "remove confusion" between the ESB's role as operator of the electricity network and a supplier in that market.

[5] ESB International Limited is responsible for the company's unregulated activities, principally providing electrical engineering consultancy services around the world.

Many of these plants are still in operation; however, as could be expected with continuing growth in demand, their combined capacity falls far short of Ireland's modern needs.

With Ireland's towns and cities benefiting from electricity, the new government pushed the idea of Rural Electrification.

Because of the risks of becoming dependent on imported fuel sources and the potential for harvesting and utilising indigenous peat, the ESB – in partnership with Bord na Móna – established those stations and ESB also built Lanesboro power station in 1958.

Located in County Longford, the plant burns peat, cut by Bord na Móna in the bogs of the Irish midlands.

Aware of the substantial waste of night-time capacity, the ESB commissioned the Turlough Hill pumped storage hydro-electric station in 1968.

The plant can generate up to 292 MW of power – but output is limited in terms of hours because of the storage capacity of the reservoir.

On 8 September 2003, two of the last remaining places in Ireland unconnected to the national grid – Inishturbot and Inishturk islands (off the coast of Galway)- were finally connected to the mains supply.

On 12 March 2007, the Irish Government Policy on Energy stated that ownership of the transmission system would be vested in EirGrid from end 2008.

EirGrid is responsible for balancing electricity consumption and generation and for the development of the power transmission system.

Residential installations followed a mixture of British (BS) and German (VDE) & (DIN) standards.

Three-phase core colours also comply with EU standards: brown (L1), black (L2), grey (L3), blue (neutral), green & yellow (earth/ground) British wiring accessories have generally been used in residential and light commercial installations e.g. junction boxes, light switches, wires and cables etc.

In industrial installations, Irish standards have always tended to follow German (DIN) and (VDE) norms.

German Schuko socket outlets were once widely used alongside the British standard BS546 round pin plugs (both 3-pin and 2-pin varieties).

Industrial, heavy commercial and stage/studio installations use European standard IS EN 60309:1999 / IEC 60309 plugs and sockets.

Various styles of bayonet cap and mounts are used for a variety of sizes and types of bulbs, including spots and halogens.

Edison screw fittings are not as common, but may be found on some imported lighting equipment, particularly from southern Europe.