The damaged San Onofre nuclear power plant is likely to remain idle until at least the end of August as investigators probe excessive wear in tubing that carries radioactive water.
The plant's operator says rotating blackouts are a possibility if a heat wave hits while the twin-reactor plant is offline.
Southern California Edison and other utilities have been scrambling to find replacement power as a precaution, including restarting two retired natural gas-fired plants in Orange County.
Southern California Edison said in a statement the company plans by the end of July to submit a plan to federal regulators to restart the Unit 2 reactor.
The plan would require Nuclear Regulatory Commission approval and that a review could take weeks or longer.
Rolling blackouts in 2000 created concerns for people around the Coachella Valley who suffered without air conditioning in 100 degree heat.
It was also a concern for people who relied on electric-powered medical devices, also motorists who were left to fend for themselves when intersections lost signal lights.
The threat of rolling outages could also have ramifications for power customers who get cheaper electrical rates by allowing their service to be limited or cut during times of peak demand.