Mystery Switch in my 1994 Calista Cove

[Buffalo_Ray]

I recently purchased a 1994 Callista Cove Class C. It is in really nice shape and has been well cared for. Everything is in working order. I have everything figured out but one thing. In the back under the closet cabinet, I have a breaker box, and a three way switch to switch from shore power to generator power to off. In between the breaker panel and the shore/gen selector switch there is another gang box with a small switch with a round glass type fuse next to it. The previous owner did not know what it was for and just always left the switch turned on. I took a photo of it but don't know how to post it as this is my first time posting. Just wondering what its for.

[Dusty_R]

With that type of fuse, I would think it's something that someone has added.

Dusty

[Buffalo_Ray]

I just purchased this motorhome, it has been winterized and I have no plans to use it till spring of 2021. I do have it hooked up shore power just to keep things charged.

[bobndot]

When plugged into shore power are you making hot water w/o the WH being on gas ?
I see you are in snow country.
If it is for the WH then it would not be a good idea to have the rv winterized and plugged in with that switch ‘on’.

[Buffalo_Ray]

The clear glass fuse is a screw-in type, such as used in house fuse panels. The switch is small like a toggle.

[DrewE]

Maybe just turn it off and see what isn't working any longer...

Is the fuse a screw-in type, such as used to be common for house fuse panels, or a 1/4" diameter cartridge type with contacts at either end, such as would be commonly used for electrical/electronic devices? And what rating is the fuse? Definitely it's the screw-in type, and I suspect probably if it's the cartridge type, the fuse would be for a 120V circuit rather than a 12V circuit. Reasonable guesses might be a 120V element in the water heater or some sort of a 120V heater/furnace system. I suppose it could also be for tank heaters (for wintertime operation). My reasonable guesses could be far off the mark, of course; they're only guesses.