The world's biggest power cut on Tuesday disrupted life in 20 states and two union territories across north, east and northeast India and affected more than 600 million people, or half of India's population.
Power officials blamed overdrawal by UP, Punjab, Haryana and Rajasthan at 1pm for the blackout that came less than 36 hours after a grid collapse that hit north India on Monday.
Overdrawal of power by states puts the grids under stress and, in extreme cases, causes the electricity transmission system to trip.
The supply tripped on Tuesday as the states continued to overdraw power despite being warned against it after Monday's blackout.
"States led by Uttar Pradesh have been overdrawing the most," said a power ministry official. He said outgoing power minister Sushil Kumar Shinde, in a report to the prime minister's office (PMO), too, named UP as the state responsible for repeated grid failures.
"States should refrain from overdrawing power beyond their quotas," Shinde told HT in the evening.
"I have instructed officials to impose heavy penalties, including a pruning of regular quotas, on such states."
The blackout disrupted road and rail traffic across the affected states but no flights were affected.
In Delhi, Metro rail services grounded to a standstill, forcing thousands of passengers to pour out on to the streets.
Non-functioning traffic signals at important crossings caused miles-long jams across the National Capital Region.
There were reports of auto-rickshaw and taxi drivers fleecing stranded commuters.
Across the country, more than 300 trains were running hours behind schedule as a result of the power crisis.
Experts attributed the two back-to-back grid failures to the huge demand-supply mismatch of 14,000 MW.
However, it should be noted that India is sitting on idle capacity of about 23,000 MW - that cannot be utilised to generate power because of a shortage of coal and gas.
"The Prime Minister should call a meeting of the concerned departments and all chief ministers and take necessary steps to ensure adequate fuel supplies to power plants," said former power secretary Anil Razdan.
Several coal mining projects are stuck because of objections raised by the environment ministry, the Coal Mine Denationalisation Bill, which can help increase production and productivity in the coal sector, has remained pending in Parliament for years and several large and medium power projects are in a limbo because of problems over land acquisition and other issues.
"The increasing gap between electricity supply and demand is a matter of concern," said Chandrajit Banerjee, director general of the Confederation of Indian Industry, adding Indian industry consistently highlighted the need for urgent steps to improve coal supplies to thermal power plants.