Metro

Manhole explosions rock Upper East Side

Three underground manhole explosions rocked an Upper East Side block Friday morning, shattering one brownstone window and scorching a Mercedes.

The violent blow-outs on East 89th Street near Third Avenue occurred after salt from snow-plowing efforts eroded the coatings of underground electrical wiring, a contractor for ConEd told The Post.

“It’s the salt — it chews up the cables,” said the worker, who was at the scene and asked not to be named.

Miraculously, no one was injured from the explosions, which occurred around 6:30 a.m.

Fire officials and residents said these explosions happen after winter street saltings.

“There’s a direct correlation between manhole incidents and salt being placed on the roads for snow removal,” said one ConEd spokesman.

“The salt gets in and corrodes the cables,” he said, adding that ConEd has been installing vented manhole covers that help reduce the pressure that can build up when cables start smoldering.

That’s small consolation to rattled residents, who had to beg to get their streets plowed and salted, only to have Wednesday’s ice followed by Friday’s flames.

“Holy smokes, it sounded like loud, loud boom,” said resident Mary Reilly,46.

“The explosion woke me up. The second one blew out the basement window. I saw flames rising high,” said neighbor Rene Ashcraft,42.

“I’m just worried for damage,” Amrinder Kang,27, said as he surveyed his white Mercedes, which had been parked on 89th near Lexington Avenue when it was blasted by heat from one explosion.

“It seems to have melted the front of the car. It’s just unlucky. I woke up early to go to work now I’m stuck doing this, now I have to pay the deductible, it just sucks.”