Sometimes mold growing around the perimeter of a socket or switch is a sign of moisture behind that wall (poor insulation, water seeping from a leaky pipe or a hole in the roof…). I’ve never seen it form a ring like that though, usually it’s right on the edge of the outlet plate.
I’ve seen similar things with homes with water damage. One of the shitty things about water damage is that you have to redo a lot of the electrics throughout the house because it can cause corrosion. Corrosion in connectors in things like outlets increases resistance and can become a fire risk.
I’m guessing the whole wall got sustained water damage causing corrosion in the outlet, increasing resistance, which caused it to throw off some heat. The heat dried out the plaster and prevented mold growth.
Sometimes mold growing around the perimeter of a socket or switch is a sign of moisture behind that wall (poor insulation, water seeping from a leaky pipe or a hole in the roof…). I’ve never seen it form a ring like that though, usually it’s right on the edge of the outlet plate.
I’ve seen similar things with homes with water damage. One of the shitty things about water damage is that you have to redo a lot of the electrics throughout the house because it can cause corrosion. Corrosion in connectors in things like outlets increases resistance and can become a fire risk.
I’m guessing the whole wall got sustained water damage causing corrosion in the outlet, increasing resistance, which caused it to throw off some heat. The heat dried out the plaster and prevented mold growth.