How we prioritize repairs
Power outages are more difficult to fix than they may seem, because often they're caused by a mix of problems.
Electricity moves from a source, such as a Columbia River dam, over a regional transmission system to utility substations. From there it runs through a series of "feeder" lines that connect with "primary" lines serving homes and businesses. Transformers at each "step" lower the voltage.
Problems can occur at each of these stages of transmission, and they can take time to diagnose and solve. If there are problems at, say, both the substation and primary line stages, fixing the primary line first won't do any good, because a problem remains at a "higher" level. That's why in dealing with outages, we start at the top of the system and work our way down.
With that in mind, here's how we prioritize our repairs:
1) Hazardous situations threatening the public safety
2) Transmission lines, which deliver power to substations
3) Substations, which distribute power to several thousand customers
4) Feeder lines from substations which affect large numbers of customers
5) Primary lines which serve between five and 30 customers
6) Outages affecting individual customers