The ivy caught on fire after a Mylar balloon from a nearby party drifted up the street and hit the power lines.
"There was a big boom, a big explosion," said Ken Carter, who lives across the street from the house with the ivy, on the corner of Lariat Lane and Pinto Court.
His wife Maria Carter and daughter Jessica crossed the street to the home, whose owners were away, to make sure the dog in the back yard was all right. Two other neighbor men rushed to put out the fire with their garden hoses.
"A metal balloon arced between the two wires," said Engineer Paul Jannisse from Station 32, San Ramon Valley Fire Protection District. "It shorted the wires and caused the transformer to pop. The short caused melted aluminum to drop into the ivy."
"The ivy was green but the aluminum was 1,100 degrees and caught the ivy on fire," Jannisse added. "The neighbors kept it in check until we got here, then we put it out."
"It was good to see those neighbors rallying," said Maria Carter. "They were there hosing off the flames - they contained the fire and kept it from leaping onto the pine trees."
The power in the neighborhood was off for a short time, and a section of Lariat Lane was blocked off by yellow tape for several hours while PG&E crews worked on the lines.
The party, on the corner of Lariat Lane and Appaloosa Drive, was reportedly for a graduation. The front of the house was decorated with rubber helium balloons and crepe paper streamers.
Mylar balloons can be powerful electrical conductors and if they hit power lines can cause equipment damage or power outages. For this reason, they must have weights on them when they are used outdoors, said police at the scene. --Dolores Fox Ciardelli