For those wondering how a single human error could take down a chunk of the power grid, it now appears there were at least two failures involved in the San Francisco blackout. The original root cause: the failure to remove safety grounds; and a second failure in the protective systems. The second failure in the protective systems is now under investigation. http://www.pge.com/whats_new/news/outage.html PG&E has added a 2nd backup system to the San Mateo plant. Exactly what the second backup system is supposed to do, wasn't clear from the PG&E statement. In addition to PG&E's internal investigation, there are now two other independent investigations by the California Public Utility Commission and the California Independent System Operator. This power outage seems to have struck a nerve. I don't remember there being this type of hostility after the double Western States blackouts in 1996. -- Sean Donelan, Data Research Associates, Inc, St. Louis, MO Affiliation given for identification not representation