Actually, approximately 50% of MW&L power lines are underground. To replace the remaining 50% would require MW&L to spend approximately $1 million per mile of the distribution system or between $150 million to $200 million in 2025 dollars, To bury the 11 miles of transmission lines we own would cost $50 million to $60 million. If we did this, it would drive rates up by at least 2 to 3 times what they currently are.
There are several reasons why power lines aren’t buried in more communities. (Data source is U.S. Department of Energy, “Undergrounding Transmission and Distribution Lines” report, 2024):
- Burying power lines is extremely expensive, roughly 3 to 10 times higher for new construction and 1.5 to 5 times higher for conversions.
- Outages tend to last longer with buried lines because it’s more difficult to locate the source of the outage and repair it.
- Underground lines also have generally shorter lifetimes than overhead, with estimates ranging from being 20-60% shorter (20-40 years compared to 30-50 years) for reasons including excessive heat buildup leading to degradation of cable insulating materials and susceptibility to moisture, which can result in corrosion.
- Underground lines can have environmental impacts and are susceptible to cable damage, particularly in earthquake-prone locations.
Read more of the U.S. Department of Energy report.