LOS ANGELES, July 16 (Reuters) - AES Corp's (AES.N: Quote, Profile, Research) 485-megawatt Unit 5 at the Alamitos natural gas-fired power station in California was back on-line by Wednesday afternoon after a two-day unplanned outage, the California Independent System Operator said.

All units at the Alamitos plant were available to the power grid on Wednesday, the Cal ISO said.

The plant is in Long Beach about 25 miles south of Los Angeles. There are six units at Alamitos, including two 175 MW Units 1 and 2, the 332 MW Unit 3, the 335 MW Unit 4, the 485 MW Unit 5 and the 495 MW Unit 6.

One megawatt powers about 650 homes in Southern California. (Reporting by Bernie Woodall, editing by Mark Porter)