Rolling blackouts are back in California. Starting about 11:45am PST, CA-ISO requested utilities start shedding approximately 500 to 1000 MW. Involuntary load curtailment is expected to continue through the evening. 11,500 MW of power production was unavailable due to planned and unplanned maintenance. An additional 1,000 MW of power product was lost this morning when a transformer fire knocked two plants off-line in Southern California. A couple of colocation and Internet service providers reported they were operating on backup generators for 60-90 minutes as their power blocks were affected. No customer loads were reportedly dropped. Sun Microsystems reported loss of power at a manufacturing facility for two hours. PG&E is rezoning those blocks "exempted" from rolling blackouts beinging this month. Some customers previously identified as being in an exempt block are being moved since they aren't sharing a circuit with a critical facility. Likewise, some circuits not identified as serving critical facilities are now exempt because a critical facility is on the circuit. Critical facility means a hospital, emergency operations center, etc.