After a wildfire, hurricane or other natural disaster causes a widespread power outage, consumers tend to ask, “Why don’t they put power lines underground?”
One significant reason is burying power lines could more than double consumers’ electric bills.
While costs vary by region, type of service and terrain, installation of underground lines is estimated to be 10 times the expense of overhead lines: $750 a foot compared to $70 a foot.
California’s Pacific Gas and Electric Co. says it costs approximately $3 million per mile to convert overhead electric distribution lines to underground, compared with the $800,000 per mile to build overhead lines.
Power outages are estimated to cost the U.S. economy $150 billion a year. But Peter Larsen from the University of California’s Lawrence Berkeley National Laboratory says research generally shows undergrounding costs far exceed benefits.
In a study of Texas utilities, he found the cost of burying lines would exceed benefits by $21 billion—30 cents of benefits for every dollar spent.
Overhead and underground power lines both have advantages and disadvantages beyond cost.
“I think undergrounding in most cases is a last solution, not a first solution, unless for aesthetic purposes,” says James L. Sweeney, professor of management science and engineering at Stanford University. “I don’t think there is a one-size-fits-all cookie-cutter solution.”
The Pros and Cons of Power Line Placement
- Less expensive to build and maintain.
- Easier to locate and repair faults or damage.
- Can be built in any terrain.
- Quicker construction time.
- Exposed to wind, wildfire and weather, including ice.
- Susceptible to damage from trees and vegetation.
- Vulnerable to blinks when animals and branches contact lines.
- Risk of damage from vehicles colliding with power poles.
- Possibility of contact with energized downed lines.
- Less attractive.
- Protected from wind, wildfire, weather, tree branches and damage from most animals.
- Less susceptible to outages from vehicles colliding with poles.
- Reduced risk of electrocution from downed lines.
- Aesthetically more pleasing, with poles and wires out of sight.
- More expensive to build and maintain.
- Time consuming and expensive to locate and repair a malfunction.
- Vulnerable to damage and electrocution from digging or other construction.
- Susceptible to damage from earthquakes and flooding of the transformer box.
- Not practical in unstable sandy or rocky mountainous areas.
- Ultimately fed by overhead lines.