SAN FRANCISCO, Oct. 8 (Xinhua) -- California utility Pacific Gas and Electric Co. (PG&E) said Tuesday that four more counties were added to areas that face historic power outage due to fire danger, and the alert has impacted extensive public services in Northern California.

PG&E announced an upcoming Public Safety Power Shutoff (PSPS) in parts of 34 northern, central and coastal counties in what would be the largest preventive power shut-offs in the state's history, which could affect more than 800,000 customers.

Although the preemptive outage measures will not be enforced until early Wednesday, many public services including high schools, universities, transportation and other sectors have already been impacted.

University of California, Berkeley (UC Berkeley) Tuesday decided to cancel classes for Wednesday due to expected campus power loss over the next few days.

It said the university has received notice from PG&E that "most of the core campus will be without power starting at approximately 8 a.m. Wednesday."

"As a result, campus officials have decided that all classes will be canceled on Wednesday," said the university on its website, adding that the campus outage will likely last up to 48 hours.

California State University East Bay (CSU East Bay) issued a special alert about its close watch of the potential PG&E power shut-off.

The Mercury News based in San Jose quoted a spokesman for CSU East Bay as saying that the university is making ample plans to address the circumstances, given their constant changes.

In San Leandro Unified School District in East Bay's Alameda County, all schools in the district will be closed on Wednesday.

"Due to the unforeseen nature of this event, San Leandro Unified School District has taken a preemptive step to close all district schools, to allow notification and planning time for families and staff," Superintendent Mike McLaughlin said.

Bay Area Rapid Transit (BART) , the public rail system serving the San Francisco Bay Area in California, said in an announcement that six of its stations are expected to experience power outage as a result of the PG&E action, and they will be powered by only portable generators.

"Escalators at stations with portable generators may be out of service during a PSPS," it said Tuesday, with elevators likely to remain operational.

California Department of Transportation (Caltrans) said Tuesday its crews are preparing for full closures in the evening of the Caldecott Tunnel and the Lantos Tunnel, two major transport facilities used by commuters in the Bay Area.

"The tunnels can't operate without power," it tweeted.

The Caldecott Tunnel connects Oakland to central Contra Costa County, while the twin Lantos Tunnels link the cities of Pacifica and Half Moon Bay on the San Francisco peninsula.

The agency said in an update Tuesday night that it is working through the night with its partners to provide power to both the Caldecott and Lantos Tunnels.

PG&E workers will install generators to keep the Lantos Tunnels open during the power outage.

The San Francisco-based California utility is cutting power to customers to prevent catastrophic wildfires under anticipated conditions of potential widespread, strong and dry winds.

PG&E was held responsible for poor management of its power lines that sparked fatal wildfires in Northern California and killed 86 people last year in what was called Camp Fire, the single-deadliest wildfire in California's history.

Several lawsuits and other requests for compensation from wildfire victims that amounted to billions of U.S. dollars forced the embattled the company to claim bankruptcy protection early this year.