And underground lines are not invulnerable to storm damage. Just ask anybody in Manhattan, where Hurricane Sandy flooded buried cables and knocked out power for millions.
Burying power lines costs five to 10 times as much as installing overhead wires, say utility officials and the regulators who must approve any "undergrounding" projects.
"Undergrounding sounds great until you start looking at a million dollars a mile for cable, and trenches through everyone's yard; then, people think differently," said Robert F. Powelson, chairman of the Pennsylvania Public Utility Commission.
Since Lady Bird Johnson championed underground wires as part of her 1960s beautification campaign, Peco and many utilities have required all-underground service for new residential developments. The cost of buried wires in new developments is included in the cost of the houses.
About 41 percent of Peco's 21,822 miles of wires are underground, spokeswoman Cathy Engel Menendez said.
Converting overhead wires in older neighborhoods runs into problems with regulators, who require the costs to be paid by those who benefit from the conversion and not passed off to other ratepayers.
Though underground lines reduce the need for utilities to trim trees, the buried systems have shorter service lives than overhead lines.
Most studies that explore converting entire systems are exercises in futility. "The cost of conversion has always been the insurmountable obstacle in each of these studies," the institute said.
Pepco, the Washington-area utility, estimated that putting all of its system underground would add $226 to the typical residential monthly bill if the utility recovered the cost in 10 years. Spread over 30 years, the figure would drop to $107 a month.
"Anybody in the utility industry would love to have a complete storm-proof system," said Stephen Woerner, chief operating officer of Baltimore Gas & Electric Co., which is also owned by Peco's parent, Exelon Corp. "But wholesale undergrounding would put a real cost shock on customers."
Sixty-three percent of BG&E's system is buried because Maryland has required all extensions of the electric system since 1969 to be underground.
Maryland regulators have allowed the utility to recover the costs of burying some sections of distribution lines if it can establish that the reliability savings are greater than the costs of burying, Woerner said. "Regulators do not permit us to underground for the sake of undergrounding," he said.
Public Service Electric & Gas Co. in New Jersey wants to spend $60 million to bury 20 miles of vulnerable power lines as part of its $4 billion "Energy Strong" upgrade proposed after Hurricane Sandy.
"We would also look at rerouting lines away from heavily treed areas, as this is a less-costly option than undergrounding," said Kristine Lloyd, a PSE&G spokeswoman. About 17 percent of the utility's 17,100 miles of wires are underground.
Peco does not have a program to convert aerial lines to underground, Engel Menendez said.
"Requests to have lines placed underground are reviewed individually and cost estimates are provided," she said. "The person or group requesting the undergrounding would be responsible for payment."
Even areas served by underground lines are fed by overhead wires. If they're knocked out, customers on the underground circuit are left in the dark, too.
Inquirer staff writer Amelia Brust contributed to this article.