Ask Bob — February 2022

Bob Pierce headshotBob Pierce answers questions about energy efficiency, consumer products, and cooperative governance. He is Clearwater Power’s Chief Operating Officer and welcomes your questions on our Ask Bob page.

Q: Every time there’s a bad storm, I wonder why aren’t more power lines underground?

A: For new construction, almost all of the power line we install is underground. That has been the trend since around the year 2000. As for existing line, we still have thousands of miles of overhead line in service. The cost for installing underground has made it a smart choice for new projects, but it would be prohibitively expensive to convert a serviceable overhead line to underground. So, as of now, a little over 11% of our lines are underground – and this number will continue to grow each year.

Underground lines have a definite advantage of being less vulnerable to wind and trees, but they’re not perfect. They are more difficult to troubleshoot when there is a problem. (Although modern smart grid technology has massively improved underground troubleshooting.) There are also questions about how long underground cable lasts. They must be heavily insulated and that insulation breaks down over time. At some point, perhaps in 50 or 60 years, that line will need to be replaced whereas, overhead line can easily last twice that long. Finally, underground wires present a concern for someone accidentally contacting them while digging. Luckily, we have a free, national system for locating underground infrastructure. Call 811 before you dig and all relevant utilities will mark where those lines are located.