This is already a write up for the sake of the report. There are exposed conductors and an improper wire splice on this branch… but what am I looking at here? I haven’t seen this before.
This was in the attic of a 1940’s home.
Thank you in advanced for any help! At this point it’s more for my curiosity than anything else.
Hope you guys are having a good weekend!
Looks like a transformer, perhaps for a doorbell.
Reduces the voltage
Bingo…or should I say ding dong? 
(I think similar were also used for old phones as well )
Thank you both for the quick responses!
I agree, transformer likely for a door bell. It is not properly installed (the black leads need to be an enclosure of some sort) so write it up.
you have never seen a transformer before???
Nope. I do houses built in this time period frequently annnd the oldest I’ve done was built in 1800. This is the first transformer I’ve seen like this.
Well, this is how they are typically wired. So the exposed connector would be a problem if on the high side I suppose. Not sure how to tell which is which from the photo.
then Ypu need to start paying attention…if those houses had door bells they had transformers…apparently You missed a few…
“This is the first transformer I’ve seen like this.”
I’ve seen transformers before, but none quite like this. This was mounted on the opposite side of the home as the front door, door bell, and chime unit. In this case, I’m absolutely sure this one was not connected to those units.
This home did however have an old RJ 4 Prong telephone jack. Brian mentioned they may have been used for old phones, so maybe it was related to that? Or maybe even something that predated that? Regardless it was already written up based on other factors.
The green transformer in the photo is slightly different because it does not have three conductors as shown in your graphic. The third conductor is an EGC to ground the transformer (more modern transformers have the EGC so that they can be connected to plastic boxes). The green transformer is grounded by connection of the threaded portion with the locknut. That would be the 120 volt side. The green transformer is required to be grounded and it is not grounded since it is not attached to a grounded metal box or metal panel enclosure, etc. Also the 120 volt connections cannot be in free air.
I wouldn’t, just few days ago I referred to a person that looked like a man by saying Mr… their name, and “it” got very offended.
You just never know, today! 
You could still use ding dong for that too. 
The two black wires are a “pigtail” for a power connection. That means there are two wirenuts off picture. Exposed wire connections are a problem right off the bat.
Just a transformer…. converting 110V to low voltage.
Thanks Robert! Good stuff.
This isnt directed toward you, but it always bugs me when home inspectors say 110 and 220. (I have been guilty of saying 220 on occasion)
It’s not accurate.
