About a decade ago, my parents decided to tear down the wall separating the kitchen and living room. Set in that wall was an electrical outlet and the thick electric cable it was connected to. To get it out of the way, they decided to move that cable under the floor. They then got the bright idea to cut a hole in a floorboard so they could continue using that outlet. This turned out to be a poor idea, as the outlet wasn't set flush with the hole, leaving it loose beneath the floor, allowing dust and grit to fall through the hole, making it all but unusable.
Fast forward to today. Water spilled on the floor, leaking through that hole, directly onto the outlet. It started sparking, and all the dirt and hair which had accumulated around it began smouldering. Luckily, the smell of burning hair alerted me to the danger, so I poured salt down that hole to smother it, shut the circuit for that particular outlet off, then went into the basement with a vacuum cleaner and cleaned that outlet off as best I could.
About a fourth of the house is now without power, which is a minor inconvenience, but I don't trust restoring power to that outlet even after it dries out.
