page_title: 2011 Southwest blackout
section_title: Background
hierarchical_section_title: 2011 Southwest blackout / Background
caption_attribution_description: English: National Interest Electric Transmission Corridor designated for the Southwest Area by the United States Department of Energy in 2007.
context_page_description: The 2011 Southwest blackout, sometimes referred to as the Great Blackout of 2011, was a widespread power outage that affected
  the San Diego–Tijuana area, southern Orange County, the Imperial Valley, Mexicali Valley, and Coachella Valley, and parts of Arizona. It occurred on Thursday, September 8, 2011, beginning at about 3:38 pm PDT. It was the largest power failure in California history.
context_section_description: At the time of the 2011 blackout, San Diego Gas & Electric (SDG&E, a subsidiary of Sempra Energy) was connected to Arizona by the Southwest Power Link, which is a single 500 kV power line (the next year, SDG&E completed a second line, the 500 kV Sunrise Power Link which was under construction during the event but still, it only parallels the Southwest Power Link and connects back to it at Imperial Valley; the remaining section into Arizona is still a single line). There is no other interconnection at the 500 kV level between SDG&E and other adjacent utilities. Rather, SDG&E is interconnected to Southern California Edison (SCE) by Path 44, a set of five separate 230 kv transmission lines which are all supplied through the switch yard of San Onofre Nuclear Generating Station (SONGS). Imperial Irrigation District (IID) has a 92 kV sub-transmission system connected to both.
caption: The Southwest Area Corridor, as of 2007
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