Authorities said there were no reports of injuries or accidents following the outage, which began around 7:40 a.m. The impact of the blackout was limited as many people were on vacation at the time.

Power was restored to all the affected areas by 10:44 a.m., including Tokyo's Ota, Setagaya and Minato wards as well as Urayasu and Ichikawa in Chiba Prefecture and Kawasaki and Yokohama in Kanagawa Prefecture.

Tokyo Electric Power Co., which supplies electricity to the areas, said the blackout began after a crane hit overhead power cables between Tokyo's Edo Ward and Urayasu.

The crane was on a 380-ton boat operated by Mikuniya Co., a construction company in Kamisu, Ibaraki Prefecture, and was running upstream with its 33-meter arm upright when the accident occurred, Tepco said.

The cables are part of a key power system to the metropolitan area that can transmit up to 275,000 volts of electricity from a thermal power plant in Chiba Prefecture to the metropolitan area.

The crane also damaged a backup power cable, which explained the scale of the blackout and why it lasted for so long, according to Tepco.

The blackout was the second largest experienced by Japan's top power company in terms of the number of affected households and offices since it was established 1951. The largest occurred in 1987 and affected about 2.8 million households and offices.

Commuter train services operated by East Japan Railway Co. and other rail companies, as well as Tokyo's subway services, were halted by the outage, which also left 1,600 sets of traffic lights in Tokyo out of action.

A number of people in the Kanto area were left trapped in elevators and automated teller machine operations were also affected by the power failure.

The Japan Times Weekly: Aug. 19, 2006
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