The UK’s second largest electricity distributor, Central Networks, which runs the regional grid in the Midlands, is being sold to an American company for £4bn.

Central Networks is owned by energy giant E.ON, which expects to tie up the sale to PPL Corp by the end of next month.

Once completed, it will make PPL, which is headquartered in Pennsylvania, the owner and operator of the largest network of electricity delivery companies in the UK in terms of regulated asset value, at £4.9bn. PPL already owns Western Power Distribution, which provides electricity to southwest England and Wales.

Central Networks has been owned by E.ON for nine years and has 133,000 km of overhead and underground cables, delivering power to over five million customers.

E.ON chief executive Johannes Teyssen said Central Networks was a “consistently high performing distribution business” but added that “the business offers E.ON limited value enhancement opportunities”.

He said the proceeds of the sale “will increase E.ON’s financial flexibility and strengthen our balance sheet”.

E.ON UK chief executive Paul Golby said PPL was an “excellent partner” for Central Networks. “They share our goal of providing a safe and reliable service for our customers and our communities.”

E.ON bought Central Networks East as part of its takeover of Powergen in 2002. In 2004, E.ON purchased Midlands Electricity for £1.2bn, merged it with Central Networks East and rebranded the new firm as Central Networks. Last year, E.ON sold its US Midwest business to PPL for $7.6bn.

PPL chairman James Miller said: “We are confident that our highly successful U.K. management team is prepared to implement operational improvements and other efficiencies that will benefit customers and contribute additional accretion to PPL earnings in 2012 and beyond.”