On the scorching afternoon of 29th July 2012, circuit breakers on the 400 kV Agra-Gwalior-Bina line flung open under the intense load. With 1000 MW power being drawn from this single line whose maximum capacity was near 700 MW, the lines were snapped open, instantly breaking the circuit.
The load then burdened the Agra-Bareilly line, which ran in parallel. It also snapped. With each line getting disengaged, the power deficit snowballed out of control and toppled every line connected in parallel. Within minutes the entire Northern Region Grid, which innervates half of India, collapsed under this cascading catastrophe. 22 states from Assam to Rajasthan and Odisha to Kashmir were plunged into darkness for 2 days. This was the world’s largest wide area blackout, with more than 62 crore people’s lives rattled for days as the engineers scrimmaged to get the grid back on its feet.