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Why do London’s manholes keep exploding?

Tom Scott | March 7, 2026



Every month or so, somewhere in London, a manhole explodes. It’s so common that it doesn’t make the news unless it’s spectacular or someone gets injured. Here’s why, complete with gratuitous pyrotechnics.

Filmed by Perspective Pictures
Pyrotechnics by Paul at Darkstar Pyrotechnics

News articles:
https://www.telegraph.co.uk/finance/newsbysector/energy/11169183/Explosion-in-city-street.html
https://www.standard.co.uk/news/london/pavement-explodes-yards-from-pedestrians-and-cars-in-old-street-a3568676.html
https://www.express.co.uk/news/uk/819198/london-manhole-cover-explodes-old-street

I’m at http://tomscott.com
on Twitter at http://twitter.com/tomscott
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and on Instagram as tomscottgo

Written by Tom Scott

Comments

This post currently has 34 comments.

  1. @s4sausage135

    March 7, 2026 at 7:32 pm

    am i the only one a little dissapointed the manhole cover behind him in the intro didnt pop jus the universe has a sense of comedic timing
    "the odds of a manhole cover exploding when your near it are tiny"
    manhole cover in the backround goes up in puff of smoke and some flames
    "but i guess its not zero"

  2. @adamzieba8364

    March 7, 2026 at 7:32 pm

    1:06 A sudden short-circuit in an underground 3-phase 10000V cable due to damaged or weakened insulation can be quite violent because there is usually a powerful electric arc that turns moisture in the ground into steam in an instant and of course the arc itself is very dangerous to anyone being close. Circuit breakers protecting power lines react much slower than those installed in homes.
    Some 10 years ago there was a short circuit in an underground cable in my home city of Łódź and it sent a flagstone flying into the air. Luckily nobody was hurt.

  3. @EricPalmer_DaddyOh

    March 7, 2026 at 7:32 pm

    Years ago we were in downtown Boston MA USA and a manhole exploded. The manhole cover went at least 10 feet into the air. In the USA manhole covers are round and weigh 250 lbs. We were probably 20 feet away and it scared the tar out of us.

  4. @Paul71H

    March 7, 2026 at 7:32 pm

    Are London manhole covers square, as shown in your test explosion? Just curious, because in the US they're circular. I've been to London, but I can't recall noticing the manhole covers.

  5. @barryphillips7327

    March 7, 2026 at 7:32 pm

    I imagine this due to under ground sewers ( there will be gases from the sewers ) and electrical cables, fart = methane gas highly inflammable explosive gas, many videos of people lighting their own fart.

  6. @alymiles1477

    March 7, 2026 at 7:32 pm

    Let's ndon you see today is built on multiple layers of old London, two the later table is riding, all the rotting vegetation from the last 2000 years,is rotting making lamp glass/bog gas pockets of this at around 3% will explode I did the work for tfl

  7. @ZarlanTheGreen

    March 7, 2026 at 7:32 pm

    In many countries, there is absolutely zero risk of something like this ….because we don't have gas pipes, all over the place. No gas piped into homes …or anything other than gas industry buildings, gas energy plants, and maybe some heavy industries, or stuff like that.

Comments are closed.




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