My building hallways have these fire doors at certain intervals. Or, at least, I assume they're fire doors... we'll just call them that.
They're held open by big magnets (one on the wall, one on the door) so they swing shut when the power goes off... or, I assume (and hope to never find out) when there's a fire... issue... I really have no idea of their purpose other than they're there, they close when the power goes out and they're held on by big magnets.
I bring them up because one of these doors happens to be magnetized right outside my door and so one of my walls is the wall that holds the magnet. And sometimes... not all the time, but sometimes, it hums. Really, really loudly.
So loudly, in fact, that I can't stand it and I go out and I un... "lock" (?) the door so the humming will stop. Ahhhh relief.
Which leads me to my question. Why on earth is it humming?
I'm assuming it's something to do with the... uh electricity? Is it bad? Should I tell someone? Or is it just frigging normal for electrical magnets to HUMMMMMMMMMMM???????
I don't know, it's just usually when I un-lock it, when someone magnet-closes it again it's quiet (for a while.. sometimes a long while) but this month, it's non stop humming when magnetized and it's annoying.... but I'm also wondering why.
So... does anyone have any idea why my building's door magnet thing is humming? (And no, I haven't gone around to check any other doors, so I have no idea if it's just my luck or what.)
P.S. I'm not 100% sure that's the only place/thing that hums, but the others I can put down to being maybe a radiator or something... this one is in the hallway and via the wall into my place.