The grid operator shut down the state\u2019s wholesale electricity market Sept. 8 at 6 p.m. due to cascading blackouts affecting 5 million customers in Southern California and Mexico. After hitting a trading high of $1,579\/MWh at 5 p.m. after the 3:30 p.m. blackout began, the California Independent System Operator set an administrative price for power originally at $250\/MWh. At 11 p.m. the grid operator reduced that price to $100\/MWh. \u201cI think the CAISO acted appropriately, although the $100 administrative price imposed during the last hours of the day is unjust and unreasonable. How can [the Federal Energy Regulatory Commission] let this happen?\u201d stated Gary Ackerman, Western Power Trading Forum executive director. FERC announced a cross-agency inquiry into the outages Sept. 9. The outage stretching from Baja California, Mexico, from the south, to Arizona on the east, and Orange County to the north grabbed headlines after heat-related peak power use this week. All 1.4 million San Diego Gas & Electric customers were out of service after 4 p.m. The utility restored power to its territory at 3:30 a.m. Imperial Irrigation District customers were mostly restored by 9 p.m. Sept. 8 Prices on the California Independent System Operator\u2019s major Southern California transmission line hit $1,579\/MWh at 5 p.m. Sept. 8, at the same time generators were bidding in negative $89\/MWh to back off the Central Coast transmission area known as ZP26. According to SDG&E, the problem first appeared near the Haciempa switchyard in an area connecting California transmission to Arizona. At 3:45 p.m. consumption in CAISO\u2019s area suddenly dropped from 43,000 MW to 39,000 MW, while available capacity plummeted from 55,000 MW to 49,000, according to the grid operator. The transmission drop caused the 2,150 MW San Onofre Nuclear Generating Station to automatically shut down. Earlier in the week, peak use on CAISO\u2019s grid rivaled the high hit July 6 this year, but still stayed under the July 24, 2006, heat storm high-use mark. The peak Sept. 7 was expected to be 45,790 MW, but did not quite reach that apex despite triple digit temperatures in much of the state. Prices remained moderate, from $35\/MWh to $50\/MWh during the afternoon, with a brief jump on one part of the system to $89\/MWh. The day before and the day after had lower forecast peaks. On Sept. 6, the forecast was 43,661 MW, and was just about met. Sept. 8 saw a 44,000 MW forecast that was on target. Prices for those days were moderate, running about $30\/MWh to $45\/MWh during the afternoons. The highest peak use recorded on the grid was in 2006 at 50,270 MW on July 24. The Los Angeles Department of Water & Power appealed for conservation, but did not see demand rise to the 2006 heat storm level. The 15,000-acre Canyon fire set by a small-airplane crash in Kern Co. did not affect the grid operator\u2019s system. On Sept. 2, the Hill Fire in Southern California tripped on 500 kV line for an hour, according to CAISO. A parallel line remained in service so no outages occurred.