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SLAC back to work after power outage

tree
Noel McMahon (CEF) stands on the fallen tree.
(Photo courtesy of CEF)

For three days, Wednesday 18th to Friday 20th of May, SLAC had no electrical power due a tree falling across the main electrical supply lines. During this period all staff, except those named by their supervisors for essential safety and maintenance work, were asked to stay away from the site. SLAC has now restored all systems needed for the safe operation of the laboratory and normal work will start on Monday 23rd of May.

All the events that caused the power outage were beyond SLAC's control. SLAC's main power lines come down from Skyline through the wooded hills west of the laboratory. SLAC maintains a wide easement under these lines, regularly trimming the trees and undergrowth to prevent interference with the lines. At 8:00 last Wednesday morning a 100ft tall pine tree, growing well outside the SLAC easement, snapped off at its base and crashed down, severing two of the three 230 KV transmission lines, immediately halting all electric power to the laboratory. This is the first time in 40 years that a tree has brought down our power lines in such a dramatic fashion. There have been power outages before but these were normally remedied quickly by restoring the 230 KV or by temporarily switching on to our 60 KV backup line. However, circumstances last week conspired against the laboratory as this backup line, which comes in from the eastern side of the SLAC site, had been disconnected because of the road work ongoing on Alpine Road.

After tremendous work by Pacific Gas & Electric, working in very inclement weather on the slope of Skyline, power was restored to SLAC on Friday evening. Since that time SLAC teams have been at work implementing a careful, phased restart of our many, complex systems and the laboratory is now ready to return to work.


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