Southern California Edison has rushed to inspect hundreds of underground electrical vaults after five of them exploded in two separate incidents in Long Beach, leaving thousands without power.
But long before the Long Beach outages, Edison had acknowledged many of the underground vaults in its service area throughout the region are in need of repair.
Electrical vaults are all around us — under sidewalks, streets, and parking lots. And they can be dangerous. Two workers died in Edison vault fires in 2013. Southern California Edison calls failures in underground vaults its third highest risk after failures of electrical conductors and equipment on poles.
For every 10 underground electrical vaults Southern California Edison inspects, it concludes that six need repair. About one-quarter of electrical vaults Edison inspects needs shoring up to bear the weight of vehicles and pedestrians, the report said.
Edison shared the information with the state Public Utility Commission's Safety and Enforcement Division last year as part of its request for rate adjustments beginning in 2015.
Edison said it wants to inspect 172,800 vaults this year throughout its vast service area to meet a requirement that it inspect vaults and the transformers, circuits and cables in them at least once every three years. That inspection list has expanded from just 8,000 vaults in 2010. The swift increase is due at least in part to Edison's broadening the criteria for inspecting vaults to include vaults that had just cable in them.
Equipment can short out, or leak chemicals. Plastic coatings on electrical cables can fray, heat up and catch fire.
Southern California Edison did visual and thermal inspections of some 300 electrical vaults July 30 and 31. The thermal inspections are looking for unusual sources of heat, which can indicated frayed cable splices, or deterioration of cable housings.
"We're continuing with additional inspections as well as maintenance of some of those vaults that we did inspect and we'll continue that until we feel that we have a safe and reliable system in Long Beach," said Edison spokesman Steve Conroy Monday.
Edison did not respond Tuesday to questions about how many of the 300 Long Beach vaults needed repairs. Edison has not said how many of the 300 vaults had been inspected in the previous three years.
Last week in Long Beach, an explosion sent a manhole cover hurtling into a house. Edison is now installing tethers on hundreds of the heavy metal covers in Downtown Long Beach to keep them from becoming dangerous projectiles.
The utility has been spending about $15 million per year on maintenance, replacement and upgrades of its Long Beach system. Edison's Long Beach District represents the largest group of power customers in its Southern California service region. The utility pays more than $6 million per year in franchise fees to the city to access the Long Beach customer base.