Unit 2 at Pacific Gas and Electric Company's (PG&E) Diablo Canyon Power Plant safely shut down today as it was designed to do after an electrical disturbance occurred in equipment that supports moving power to the state’s electric grid. Unit 1 continues to safely generate power. Results from the preliminary investigation indicate the electrical disturbance was the result of a flashover event on a lightning arrestor, which is located on the non-nuclear side of the plant. The system performed as designed and automatically went off line to protect equipment. Unit 2 remains in a safe condition and will return to service after the cause is fully understood and the equipment is tested. PG&E has informed the U.S. Nuclear Regulatory Commission and appropriate local and state officials.