Why can PSE place power lines underground in order to avoid pruning?
Approximately 50 percent of PSE’s distribution power lines, which serve neighborhoods, are buried underground. Due to the long-distance reach of transmission lines, which bring power supplies from generating sources to our region, the majority of PSE’s transmission lines are overhead. Due to their complexity, underground transmission lines are custom-made, which significantly increases the costs to customers for their design, installation and maintenance. There are significant challenges associated with undergrounding high-voltage lines. For example, all trees and vegetation must be removed in order to bury the underground cable; outage durations can dramatically increase because it can take much longer (days and weeks v. hours and days) to locate an outage and complete repairs; and underground transmission cables cost many times more than overhead lines.
