UNDER-INVESTMENT in California's ageing power grid was exposed when a transmission cable was accidentally cut, triggering widespread power cuts in Los Angeles.
Contractors severed a cable at one of 20 'receiving stations' serving Los Angeles at 12.30pm on 12 September.
Receiving stations are connected to a mix of coal and gas fired power stations, and hydro and wind turbine generators across Los Angeles.
When the Toluca Lake receiving station connection was cut, power surged through cables to other receiving stations.
This overloaded the grid, triggering the automatic shut down of another receiving station and four power stations, Los Angeles Department of Water & Power (DWP) said.
As a result power supplies to nearly 2M people in Los Angeles went down. Neighbouring supplier California ISO also lost 2,100MW of power.
'This was not unlike the 14 August 2003 situation, when the eastern seaboard grid collapsed, ' said a spokeswoman for state-wide supplier California ISO (NCEI October).
'We were able to control it by dropping load quickly, but it was alarming. We've got a fragile system and have been pushing for the last few years for more investment, ' she added.