Energy regulator Ofgem has launched an investigation into British Gas, E.ON and npower over their low roll-out performance of advanced electricity meters.The government's advanced meter roll-out scheme has required electricity suppliers to fit 155,000 business customers with advanced electricity meters by April 2014.Based on Ofgem's assessment, the roll-out was only 75% complete in electricity, compared to 86% complete in gas.British Gas, E.ON and npower had the lowest completion rates in electricity, accounting for over half of the 40,000 advanced electricity meters still waiting to be installed."We are disappointed in the overall performance of the majority of suppliers concerning the roll-out of advanced meters to business customers," said Rachel Fletcher, senior partner for Ofgem's markets division.She added: "Regulatory and government programmes are not optional and failure to meet these in a timely way causes consumer harm. All suppliers can and must learn the lessons from the roll-out of meters for business customers and apply them to the domestic smart meter roll-out."