Why Do Manholes Fly Into the Air Sometimes?

Frp manhole covers

Did you know that even the most heavy duty manhole covers can explode, sending hundreds of pounds of metal skyrocketing into the air? Though it may seem strange — and it 100% is weird — there’s a perfectly rational explanation.

You see, what happens when manholes explode is an explosion. Aging, corrosive chemicals, overloads, and the biting of rats can fray underground cables, which carry about 13,000 volts of electricity.

These wires heat up the insulation, causing it to smolder, catch fire, and release gases. This is where things start to get hairy. It’s these gasses that build up inside manholes, waiting for something to wrong.

And of course, something does go wrong. The electrical wires arc like a bolt of lightning and ignite the gasses. If you’ve ever seen a picture of the famous Hindenburg explosion, then you know what happens next: a really, really big explosion.

It’s such an explosion that causes manholes to fly off.

What’s crazy though is that it doesn’t always result in a manhole cover flying sky high. Sometimes, all the explosions do is flip the manhole cover. It all depends on just how much gas was built up. Oftentimes, there’s not even any explosion at all. There’s just a lot of smoke, and a lot of fire (or only a little smoke and a little fire).

Power companies have started to actually replacing solid manholes with slotted ones, so that they can release the gas. With a manhole cover that lets gas out gradually, it’s harder for the gas to build up. Consequently, the chances of an explosion happening are greatly reduced. That’s not to mention the fact that they can also give an early warning, alerting people that there may be an issue soon.

And that is why manholes fly into the air sometimes. If you have any questions, feel free to share!

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