APS says Yuma power outage probe continues

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YUMA, Ariz. (AP) -- An Arizona Public Service official says the cause of a massive power outage that affected millions people on Sept. 8 is still months away.
Two federal agencies launched a joint inquiry.
Investigators have been visiting all of the utilities involved in Southern California, Arizona and northern Mexico.
APS vice president of energy delivery Daniel Froetzcher tells the Yuma Sun the utility is a willing participant in the investigation.
According to APS, an employee made a mistake while performing a maintenance procedure at the Gila Substation northeast of Yuma, tripping off a 500-kilovolt transmission line that runs from Phoenix to Yuma.

A rippling effect led to the loss of power for up to 7 million residents in Arizona, Southern California and Mexico.