Along with the power outages, what causes "rolling blackouts" like tonight's?

Senior Moments

An inability to provide enough power to meet demand. These rolling blackouts are used to minimise the effect of the shortfalls by spreading them over large areas for shorter periods. They are common in California. We in the UK are being told that the recent power cuts, that have hit the East Coast of America and Eastern Canada, are being blamed on on ligntning strikes and fire damage. Aug 15 03, 2:34 AM

sequoianoir

Yes but the "rolling blackouts" shouldn't have happened as they did. There is a large grid distribution system that is all interjoined with power going into it from all over the US and Canada. If one part loses some of the generating side and there is a shortfall, it should be re-routed from somewhere else. However if this were to cause an overload to any specific grid section then this should not happen and individual sections would be shutdown to protect the rest. It appears this disconnecting did not happen and "an overload" rippled across the grid. Aug 15 03, 6:20 AM