As states recover from the devastation of Superstorm Sandy, especially damage from wind and trees falling on overhead power lines, many people are now debating whether to transition from overhead to underground systems in hopes of reducing weather-related outages.

In response to Sandy, the Edison Electric Institute (EEI) issued an updated report: “Undergrounding of Overhead Power Lines.” EEI is the association of shareholder-owned electric companies that represent approximately 70 percent of the U.S. electric power industry.

Even when storms are not wreaking havoc on utilities, many communities want to improve the aesthetics of their neighborhoods by moving lines underground. Naturally, there are many issues to consider because of the substantial implications for reliability and cost.

Over the years, many states have issued reports that addressed whether undergrounding would improve the reliability and availability of electric service during and after major storms. An earlier EEI reliability report said that 67 percent of outage minutes were weather-related.

urrently, no state has recommended the wholesale undergrounding of its utility infrastructure. The high cost of conversion has always been the problem.

Because of the importance of cost to consumers, EEI polled customers concerning their willingness to pay for undergrounding. The results indicated that 60 percent of electric customers were willing to pay at least 1 to 10 percent more on their bills for undergrounding. Eleven percent were willing to pay up to 20 percent more. However, fewer than 10 percent were willing to incur an increase of 100 percent to pay for the more realistic cost of undergrounding.

This information confirms the experience of most utilities and state commissions that customers have limited tolerance to pay the higher costs for undergrounding.

EEI also looked at major storm data from the previous nine years to determine what trends and impacts these events are having on the electrical industry. The data was somewhat inconclusive because the number of storms had increased, but the average outage time per customer declined at times. This may mean that utility restoration responses have improved with the increased use of mutual assistance. Some measures of reliability indicated that underground electric infrastructure has only a slightly better reliability performance than overhead electric systems, while other measures showed a higher reliability factor for underground facilities. One explanation may be that many underground facilities are fed by overhead facilities, which can become disabled during storms. Repairs and upgrades to underground outages are also often more complex and costly. Dramatically, Sandy also proved that some underground facilities are highly vulnerable to flooding and water ­damage.