Calcutta, June 4: A nor’wester whooshed through heatwave-scalded Calcutta this evening, sparking a major electrical fault in the CESC that plunged most of the city’s northern parts and vast areas of the central into darkness.

CESC officials said “a long piece of cloth or a sari” blown in by the storm got entangled with three phases of the 132-kv switchyard at Taratala around 6.45 pm, igniting a big flash that tripped the Titagarh and New Cossipore power plants.

“Immediately, we had a 330 mw shortfall on our hands. We were helpless as we did not know what happened. We were literally groping in the dark,” an official overseeing the CESC’s northern region said.

The power failure hit Calcutta airport for 30 minutes. Although there were no lights in the terminal building, flights were not disrupted. Emergency lights were used in some places.

Raj Bhavan, Writers’ Buildings, Lalbazar and the CESC headquarters at Victoria House were not spared. But areas served by the State Electricity Board were unaffected.

“According to our reports, the long piece of cloth, which could have been a sari, got wrapped around a vital portion of the phases in the switchyard. This led to the disaster,” said S.S. Sinha, executive director of the CESC in charge of distribution.

By 8.30, power supply was restored in Manicktala, Kankurgachhi, parts of Lake Town, Sribhumi, Patipukur, Paikpara and other north Calcutta areas. CESC officials said by late tonight, the fault would be fully rectified.