Aug. 31--PROVIDENCE -- National Grid crews are set to start working to repair the underground cable that failed last week leading to two power failures on successive days.
Workers for the utility will replace two sections of the 115-kilovolt cable that runs under South Main Street in the area of the Licht Judicial Complex. The repair job is expected to last several days this week, said David Graves, a spokesman for National Grid.
A weak spot in the cable -- most likely a splice where two sections were joined together -- overheated and caught fire on Thursday night, sending an area that included the Providence Place mall and much of the East Side of the city into darkness. Four electrical substations in the city lost power, affecting some 6,500 National Grid customers.
Power was restored to all customers within a couple hours that night by switching to back-up equipment at the Clarkson Street substation. But on Friday afternoon, that equipment faltered and the mall again lost power, along with about 8,300 customers in Providence. The outage, however, was brief and service was restored within nine minutes after National Grid switched to yet another power source.
An inspection afterward found that the back-up system at the Clarkson Street substation appeared to have been damaged by lightning before National Grid brought it into use on Thursday night. Graves said that it's believed the damage occurred during thunderstorms that passed through Rhode Island Aug. 12.
"The damage wasn't apparent until the equipment was put into use," Graves said.
If the system wasn't damaged, the outage last Friday likely would not have occurred, he said.
The power failures come as National Grid is working to build a new substation on South Street.
Graves said the new substation probably would not have prevented the outages because of the locations of the problems, but he said that the facility will enhance the resilience of the overall electric system in Providence.
The cable under South Main Street is fed from the Franklin Square substation, which gets power from the Manchester Street Station, Brayton Point Power Station in Somerset, Mass. and a power line that runs from Millbury, Mass.
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