The report says the poles were loaded with electrical and telecommunications wires and other equipment.
The report found a similar cause in another 2007 brushfire in San Diego County that destroyed 1,300 homes.
Those two incidents are prompting officials to address the risk of overloaded power poles.
/*Southern California Edison*/ and other regulated utilities have been meeting with commission representatives to discuss revising state standards for utility poles.
Also, a hearing is set for May 13 in San Francisco to determine if Southern California Edison and companies that shared utility poles violated safety standards.