I have told this story a couple of times on here, but it's a good one.
In the days of Norweb (in the NW), I obtained permission from them to cut the seals in the case of a rewire or board change. I would leave a cert and they would attend a few days after and reseal.
One day I was working on an estate in Chorlton doing a board change.
This estate apparently was the first in Manchester to be built with a leccy supply.
I had cut the seals and removed the fuse and busied myself disconnecting, fitting a new back board etc...
After a while, there was a knock on the door. It was a Norweb guy.
"Have you got electric?"
"No, I've pulled the fuse because I'm doing a board change."
"Bloody hell" said the bloke, "That explains it!"
"Explains what?" I asked.
"This whole side of the street is off downstream of this house!"
"Wait....." I started, trying to figure out what he'd said, "But me pulling an intake fuse for this house shouldn't affect anyone else."
It turned out that the PILC cable was looped from one house to the next, all the way down our side of the street.
But not only that, it was looped on the wrong side of the fuse, so pulling a fuse in any house would turn off the leccy in all the houses downstream of it.
I'm not sure the Norweb guy realised quite how wrong it was, but I made a phone call to their offices to report the situation.
As far as I know, the situation hasn't changed.