By JULIE WATSON 05/ 1/12 07:22 PM ET
SAN DIEGO — Federal energy regulators on Tuesday blamed inadequate planning and lack of grid coordination for a massive blackout last year that started with the loss of a single transmission line at an Arizona substation and quickly affected millions of people in Southern California and Mexico’s Baja California.
The Sept. 8 outage that lasted through the night shows the need for close communication between major utilities and smaller operators, and for everyone to update their emergency settings, officials said.
The blackout was caused by many of the same problems that triggered a 2003 outage that cut power to 50 million people in the Midwest and the Northeast, regulators said in a teleconference from Washington.
It was another reminder that U.S. transmission lines remain vulnerable to cascading power failures despite the safeguards that are in place.
The system is built to quickly compensate for glitches – like the loss of a single line – but a lack of understanding of what was happening between neighboring operators caused the problem in Arizona to balloon into something much bigger than it should have been, according to the joint report by the Federal Energy Regulatory Commission and North American Electric Reliability Corp.
When a maintenance worker caused the loss of the line operated by Arizona Public Service, it immediately overloaded adjacent systems stretching to California and northern Baja California.
The outage knocked out traffic lights, causing gridlock on roads in the San Diego area. Two reactors at a nuclear power plant along the California coast went offline after losing electricity, and nearly 3.5 million gallons of sewage spilled into the ocean, closing beaches in San Diego.
People on both sides of the U.S.-Mexico border spent the night struggling to fall asleep in high temperatures that reached 115 degrees in desert areas. There were no reported deaths or injuries related to the outage.
“This report highlights the growing need for more coordination of grid operations in the West,” FERC Chairman Jon Wellinghoff said in a statement.