Dont have a clue 
The home does have a sprinkler system, and I thought it may be somthing for that. It looks like some type of photo eye.
Any ideas?
Day Night sensor for external / driveway lighting?
I asked the owner, and he didn’t know. He lived there 4 years
Agree, looks like a photo sensor for lighting.
I’ve got one just like it on the east side of my house. It controls the driveway lights, on at dusk, off at dawn. Where does the liquid tight conduit go or come from?
It looks like a dusk to dawn light kit missing the light. I’ve installed several.
I have one on my home and the conduit goes to the light on brick mailbox.
Photo eye it is!
It looks like what I have on my and all houses in our area . It is sender from the water meter .
They can read what the meter records from out side the home .
Yup, looks like a photo cell, this one is made by Intermatic.
Was there an electrical box behind that plate? Also the LFNM isn’t properly secured.
http://ecx.images-amazon.com/images/I/31L8jLXjO9L.SL500_AA300.jpg