You may have heard that manholes are exploding all over the city, and those explosions are causing earthquake-like rumbles and sonic booms. When the 300 pound covers blow off, they can fly up to 50 feet. Though no civilians have died from exploding manholes, several have been critically injured.
But why is it happening? Here’s the recipe for an exploding manhole:
Step 1: All the salt that gets put on the roads when it snows seeps under the manhole covers.
Step 2: The salty water that’s dripping down erodes the insulations on the wires, because many of the electrical cables underground are old and frayed.
Step 3: The salty water conducts electricity from the corroded wires, creating sparks and small fires.
Step 4: The fires release combustible gas, building pressure inside the man hole.
Step 5: The sparks from number 3 ignite the gas, creating an explosion.
ConEd is taking steps to prevent explosions in the future, by transitioning to ventilated manhole covers, and replacing the old, frayed electrical wires. But for right now, be sure to watch your back.
If you see smoke or flames coming out of a manhole, immediate turn in the opposite direction. And while you’re at it, call the fire department.
Cover photo credit: S Pakhrin/Flickr