[sgdaniels]

I recently purchased a home built in 1950 in Phoenix Arizona. Inside the hallway closet there is a 20amp electrical switch that seemingly goes to nothing. The wires go up and to the right. There is no evidence of a previous light in the closet. To the left of the switch there was a metal cone that was threaded onto a thin metal rod which is mounted inside of a copper pipe. When I removed the cone, there was a moderate level of condensation that came dripping out. Any ideas as to what this could possibly be would be very helpful. The other side of the wall is the bathroom wall which does not have any water fixtures (on that particular wall). Pictures below.

View of the inside of the pipe with the bell shaped cone and the retaining bolts removed. both had PTFE tape on the threads, and only the inside bolt allowed any water through when removed, flow was not constant, only stored:

View of how close the light switch was to the piping fixture, my hand is ~ 8 inches long tip of middle finger to wrist. post-removal:

Strange bell shaped covering cone, looks almost cosmetic, served no purpose that could be determined.

Also worthy to note, the end of the metal (brass?) rod is Splined like an input shaft for a motor, or an axle shaft of a car, it's hollow for the splined part to a depth of ~ an inch.
Sorry for the lengthy first post, i really appreciate any help you guys can provide on this very strange little mystery i stumbled upon today.

 

[Red Squirrel]

That's your water main. It's what happens when you hire an electrician to do plumbing! First I hear of 20 amp water service though.

In all seriousness, it's hard to tell just from looking at it. Could it be for the furnace? Check nearby outlets to see if they are controlled by it, maybe? Christmas light outlet outside maybe? You'll pretty much have to determine if it's even live, if it is then turn it off and go look for stuff that is off.

Oh, was there maybe a kitchen of some sort there? Maybe there was a garbage disposal?

 

[TTW]

My first impression is that it might have been an old gas light.

Have you found any other evidence of gas fixtures or piping, say in the basement?

 

[rudy001]

That looks like a shower valve stem.

Possibly setup for a swamp cooler. The switch turned on the swamp cooler and the valve was the shut off to it. Thats my best guess.

 

[Billy_Bob]

Arizona has "Evaporative Coolers" on the roof. These need a switch to turn them on and a water valve to supply water in the summer, but shut if off in the winter.

It is common in Arizona to replace the evaporative cooler with Air Conditioning. Then the valve and switch no longer go to anything. There may be an outlet and water pipe stub sticking up on the roof above that area?

Evaporative cooler on roof...