A power failure on July 2, which affected two million people
from Canada to Mexico, began with an Idaho transmission line
that short-circuited when electricity jumped to a tree that had
grown too close, investigators say. The failure in that line,
combined with record demands of power during hot weather, led to
a ripple effect that cut power to 15 Western states and parts of
Canada and Mexico, said Corry Alsberg, a spokeswoman for a group
of regional utilities. Investigators announced their conclusions
about the blackout -- which lasted a few hours -- at a closed
meeting of the Western Systems Coordinating Council on Friday.
The tree caused the electricity to arc, or flashover, in a
remote area about 100 miles east of the Kinport substation in
southeastern Idaho. The Idaho line carries 345,000 volts. The
flashover, in combination with several other factors, was enough
to trip the first in a series of blackouts. Other factors in the
failure included near-record hydropower generation in the
Pacific Northwest an