Utility spokesman Joe Molica said that all but 30 customers in Menlo Park had their power restored by about 1:30 a.m. today, and that the remaining customers are expected to regain power at about 2 p.m., when the final repairs are completed.
The "vast majority" of customers affected, mostly in the Menlo Park and Portola Valley areas, regained power Monday afternoon. PG&E crews continued to work on repairs overnight, Molica said.
The outage began when one of the utility's transmission lines "tripped offline" at around 11:40 a.m.
Molica said that likely happened when another wire came into contact with the transmission line.
Transmission lines, he explained, carry power from the generation source to substations, which then "step the power down" and distribute it to customers via distribution lines.