The Federal Energy Regulatory Commission and the North American Electric Reliability Corp. have announced a joint inquiry into the Sept. 8 power outage that left more than 1 million customers in Southern California, parts of Arizona and Northern Baja Mexico without electricity. As of 2:15 a.m. PDT Sept. 9, all but 200 MW of the initial 4,300 MW lost had been restored.

FERC and NERC will coordinate with the Department of Energy and other federal agencies, the California ISO, the Western Electricity Coordinating Council, California and Arizona state regulators and the companies involved to monitor the situation. The inquiry will focus on causes of the outages.

“NERC and FERC are partnering to conduct a full inquiry into the cause of this event,” said Gerry Cauley, president and chief executive officer of NERC. “Partnering brings together the expertise of both organizations, and emphasizes the importance placed on reliability of the bulk power system.”

“This inquiry is an effective way for us to protect consumers and ensure the reliability of the bulk power system,” FERC Chairman Jon Wellinghoff said.

The initial focus remains on ensuring a timely and safe restoration of power to customers. Updates will continue as more information is confirmed.

FERC is charged with oversight of reliability of the nation’s bulk power system. FERC has designated NERC as the organization that develops and enforces mandatory reliability standards.