Roberto Bonaccorso from Seattle City Light just sent me an email with the most up to date information the city has on what caused last night’s power outages in Queen Anne and Magnolia. He writes,
What we (City Light) know at this point is that a planned repair in an underground vault near the Seattle Center was completed on schedule early Saturday morning. In order to prepare a test of the repair, power for the Center was diverted to an alternate feeder (a feeder is a big line that transmits power to large areas of the city).
At that point, a junction box failed on the alternate feeder. Power was switched to a second alternate feeder in order to identify what repairs needed to be made. On Sunday, we had a failure on this second alternate feeder at another location.
Crews were sent out to isolate the problem and our switching operators were able to restore power to customers using multiple feeders. Meanwhile repairs are ongoing to the original junction box and failed cable.
At this time power has been restored to all affected by last night’s outages in Queen Anne and Magnolia. According to Bonaccorso there is no estimate for the completion of the original repairs.