Oh wow, great find! (especially considering it’s a white one, which are very rare to find!) Interesting how it’s flush-mounted like that too (since I believe normally MASSes are meant to be mounted in front of those trim plates rather than behind).
Nope, that’s a proper flush plate
Is that used for fire or general signaling?
Oh, really? Had no idea.
Could be either going by the fact that it’s white & apparently doesn’t have any “FIRE” lettering either (as rare as such MASSes are, if they even exist to begin with).
It’s used for security
Really? Huh. Do you know what it’s hooked to exactly? (& when/why said thing activates & thus in turn activates the MASS)
It’s connected to an emergency exit door and activates when the door is opened. (Someone who worked there told me it does 800hz)
Ah okay. Sorta odd they wouldn’t set it on 800Hz-1000Hz alternating instead if you ask me, since that’s probably more noticeable & audible than a straight & plain tone like 800Hz.