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News photo
A barge crane sits lowered Monday after it hit power cables over the Old Edo
River, causing a major blackout in the Tokyo area.
KYODO PHOTO


“There are lots of locations similar to Monday’s accident site,” said a senior official at the Ministry of Economy, Trade and Industry.
The outage occurred when a raised crane on a barge accidentally damaged power lines, cutting off electricity to 1.4 million households and offices and disrupting road and rail services.
Tokyo Electric Power Co. later activated another cable route, officials of the utility said.
Experts say Tepco must devise steps to minimize damage from a range of situations. These could include compiling detailed rules for construction firms operating floating cranes, they said.
Tepco took some three hours to restore power as it first had to confirm that its transformer substations could operate safely. The experts said the utility must introduce a backup system to restore power more quickly.
A Tepco official said the damaged cables were strung “at a high enough position,” adding the height was determined in consultation with the Tokyo Metropolitan Government. The cables are strung 16 meters above the Old Edo River.
Tepco “could not foresee” that both sets of cables would be damaged, said an official in its transmission route supervision section.
The experts said that burying the cables could be the safest way to go, though they acknowledge that doing so would be expensive. Less than 30 percent of the power lines in areas under Tepco’s jurisdiction are below ground.
However, within Tokyo’s densely populated 23 wards — the core area under Tepco’s jurisdiction — more than 90 percent of power cables are buried because Tepco was unable to find land to accommodate steel towers.
Crane setup blamed
CHIBA – Monday’s massive blackout in the Tokyo area was caused by workers who were trying to increase efficiency by erecting the crane that hit power lines while its barge was still moving, according to police sources.

Police were looking Tuesday into whether the operator of the barge, Mikuniya Co., a construction company based in Kamisu, Ibaraki Prefecture, is guilty of violating the electricity enterprises law by disrupting electrical transmission, the sources said.

The 43-year-old manager of Mikuniya’s Chiba office and other company officials told police the workers erected the crane while the barge was still moving to a dredge site so they could get a head start.

The officials said they were aware of the Tokyo Electric Power Co. cables, contradicting earlier statements claiming they didn’t know the cables were there.

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