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POWER: San Mateo/San Francisco power outage report
- From: Sean Donelan
- Date: Wed Dec 09 00:31:00 1998
Howdy, I'm back from vacation. By popular demand, a summary of the
San Francisco/San Mateo power outage on December 8, 1998.
At 8:15am workers making changes to 115-kilovolt lines at the San Mateo
substation failed to properly ground the system. When they turned on
the power, it caused a low frequency condition and tripped protective
breakers on the substation. It also caused a cascade effect, tripping
the Hunters Point and Potrero power plants. This isolated San Mateo
County and northward to parts of San Francisco City from the electrical
grid primary power sources. Aside from the human error, the system worked
"as designed to protect the rest of the grid."
Approximately 375,000 customers were without power, including San
Francisco Airport (SFO), the Pacific Stock Exchange, traffic lights,
and cable cars. BART (subway) used emergency power to bring trains
to the next station, and then shutdown. Since the electrical grid
was isolated, PG&E had to "blackstart" the system on a circuit by
The SFO airport power was restored at 9:10AM. The San Francisco Office
of Emergency Services was activated at 9:22AM according to EDIS.
At 1:00PM about 200,000 customers were still without power. PG&E
estimated that full restoration would be completed by 2:15PM, but
some customers were still without power through the afternoon.
No major injuries have been reported directly attributable to the
power failure. No major Internet provider reported any network
problems directly attributable to the power failure.
Since this outage was caused by a PG&E error, customers may make
claims for some types of damages. Other damages may be covered
by private insurance.
In other news:
On December 7, 1998 PG&E donated $87,000 to San Fransico's
Emergency Services Communications Center to install extra back up
electrical facilities for the center. The new facility will work
with PG&E during major service interruptions to establish restoration
Sean Donelan, Data Research Associates, Inc, St. Louis, MO
Affiliation given for identification not representation