There is a key to lock it closed, and the same key will lock it either on or off. In keeping with a Victorian Bell/Butler Board but not near it in the house.
I guess it must be some kind of isolator switch, but I know nothing of its history.
It's a set of switches paired together to be a single pull double throw switch.
Agreed, but without seeing the rest (back mostly) hard to say exactly what it does.
If it’s part of the butler bell, how many rooms were on it? It may have been a switch to make it go to all rooms in on position and only selected rooms in another. Just guessing here.
I wonder if it was door bell & butler bells
Both switches would turn off/on at the same time. If one was a door bell and the other the butler bell, this switch would make them both ring at the same time.
Looks like a antique double pole single throw switch (DPST) meaning it has two single switches connected mechanically but separate electrically (it can switch on and off two circuits at the same time). The contacts look fairly beefy so I would guess it could handle fair amount of current and the lock may have been to just keep people from getting shocked. Might have been the cutoff for the power to the bell board.
Edit: Looked around and can’t find one like that. Is there a plate on it anywhere? Could you show the cover and back of the box.
Guessing by the size of the wires this was meant to switch Mains power and was set to cut/connect both legs at the same time. Since you mentioned a butler call board, it could have been used like this.
Are there any markings on the bottom or anywhere else?
I enjoyed r/whatisthisthing, and I hope c/whatisthisthing catches on! Challenge mode is a great idea.
Is it mounted to the wall? What’s behind it? What’s on the left of the hinges?
Some sort of locking mechanism, I don’t know, just curious about the context.
Yes, wall mounted. Each panel has a couple of cables running out of the back.
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Currently in CHALLENGE mode: If you've got something obscure knocking about, post a picture, and let's see how we do. Please prefix such posts with "CHALLENGE:" so we know we've got a fighting chance.