In some locations, a large number of faults are due to squirrels and other animals. But as they crawl from power lines to transformers, they can cause a fault. When this occurs, most customers see only a temporary dimming of the lights. Squirrel guards on the transformers prevent some faults, but not all. In many locations, the power runs underground.
Faults can occur when contractors accidentally damage underground conductors while digging.
This type of damage can lead to long interruptions and voltage sags for many customers. Equipment failure All equipment has a useful, or expected, life span, and PGE is proactive in replacing equipment near the end of its expected life. But some equipment failures still occur. These failures account for only a small percentage of sags and interruptions each year. The closer you are to where a power fault occurs, the deeper the voltage sag will be at your facility.