The government has ordered sweeping measures to fight the spread of the coronavirus, shutting down much of the economy and asking people to stay inside and avoid non-essential travel.
"We have (around) 3,000 colleagues currently on furlough arrangements from our total UK workforce of around 7,500 full-time employees," a spokesman for E.ON UK said in an email.
The affected staff include a range of field and metering technicians as well as customer operations and support staff across both residential and business operations, E.ON UK said.
E.ON UK said staff affected will receive 80% of their salary under a government-backed scheme and it would top up payments to ensure everybody received 100% of their total salary.
E.ON UK?s parent company, Germany?s E.ON, also owns the Npower energy supply brand in Britain following a far-reaching asset swap with RWE that included the break up of former Npower owner Innogy.
Around 1,000 of Npower?s 5,500 staff are also being furloughed.
Britain's second largest energy supplier OVO Energy said last week that it had also furloughed around a third of its workforce.
By Susanna Twidale