BORD Gáis has grown its share of the domestic electricity market to just over 12%, according to new data by the Commission for Energy Regulation (CER).

The figure for the third quarter of 2009 compares with a market share of 8.9% for the second quarter, the CER said. Airtricity, the windfarm operator, grew its share of the domestic market from 1.48% to 3.28%.

As a result of the gains by Bord Gáis and Airtricity, ESB's domestic market share fell to 84.4% from 89.3%.

The CER said around 116,000 people switched electricity supplier in the third quarter, equivalent to 5% of the overall number of customers moving. The number of people switching was lower than in the previous three months, it said.

For large business customers, ESB Independent Energy (a subsidiary of the ESB) was the market leader with a share of 29.4%. The ESB itself had 24.7% of the market.

For medium-sized businesses Energia, part of the Northern Ireland power company Viridian, was the biggest electricity provider by customer numbers, with just over 31% of the market. It was followed by the ESB and Airtricity.

ESB's share of the small business market declined to 54.55% from 57.6%, with Energia and Airtricity making gains.