Federal Power Minister Sushilkumar Shinde told reporters that the monster outage, which struck around 1:00 pm (0730 GMT) in the middle of the working day, was caused by states drawing power ‘beyond their permissible limits.’

There appeared to have been a domino effect, with the northern grid drawing too heavily on the eastern grid which in turn led the northeastern grid to collapse.

‘Half the country is without power. It’s a situation totally without precedent,’ said Vivek Pandit, an energy expert at the Federation of Indian Chambers of Commerce and Industry.