A lighting bolt struck the main power feed to the SLAC National Accelerator Laboratory at about 11 p.m. Thursday night. The line, which is located in a remote area of the Santa Cruz Mountains only accessible by helicopter, was repaired by approximately 6:30 p.m. Friday, according to a PG&E spokesperson.

The damage to the main electrical transmission line shut down the linear accelerator, rendering Friday a “lightning day” for the 1,600 SLAC employees who stayed home due to the outage.

SLAC planned to bring its systems back online slowly as a precaution following the shutdown.

The SLAC campus went on auxiliary power following the strike and only brought essential personnel on site Friday. SLAC media manager Andy Freeberg told Palo Alto Online that there was no danger resulting from the strike or shutdown.

The electrical transmission line that was damaged can carry between 4,000 and 34,000 volts of electricity, according to a PG&E spokesperson. A lightning bolt can carry one billion volts.

Three fire alarms were activated as a result of the lightning strike to the power line, prompting the Palo Alto Fire Department to respond.

The same storm spawned roughly 700 lightning strikes around the Bay Area overnight on Thursday into Friday.

— Alice Phillips