Weird, 'murican here and I've never seen one on a ceiling before.>>92579856
You must live in some parallel reality, no building I have ever entered has had one placed on the ceiling, only ever on the wall like in that picture. Hell, mine's on my wall right now with another at the other end of the house on another wall.
You're not talking about the sprinkler systems right? Because those are always ceiling-based.