NEW YORK (CBSNewYork) -- Manhole explosions are one of the side effects of a tough winter.
Since last week's snowstorm, crews have responded to at least 300 manhole fires in New York City, including two Thursday morning on West 71st Street near Central Park West, CBS2's Mary Calvi reported.
Experts said the salt spread on icy roads is bad for the 95,000 miles of cable under the city's streets.
"Mentally, you're just prepared what to expect, like you're going into battle," said Con Edison underground operating supervisor Al Munro.
When the ice melts, the salty runoff floods into manholes packed with electrical equipment.
If any cable was broken or there is faulty insulation, the salt can come into contact with the copper wiring, causing a spark that could ignite trapped gases.
"You'll often see in these situations flames shooting out of the hole," Con Edison spokesman Michael Clendenin said.
Five years ago, Con Edison began installing vented covers that let trapped gasses escape, but it's not a perfect solution.
"We're always looking at new technologies to try to minimize these kinds of events," Clendenin said.
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