There is no way to tell where that black cord goes or what its for. Can you shine a light and mirror up into the wall and see if it appears to connect to anything? Since it goes up and the attic is above, my guess would be an attic fan or other device in the attic.

Its also hard to tell the wiring configuration of the lower left box. It has a wire behind it on the stud face, and that may be the power source, or maybe the power source is the wiring coming down from above.

Buy a cheap outlet tester and plug it into each of those three boxes. If they have power, turn off breakers until you find the right one to cut all power (and see what the breaker label says). All of these boxes would be easy to remove (with power off), but its hard to tell what you are disconnecting.

Bruce

Since they all look like they are connected, I wouldnt be removing them, until you had a licensed electrician come and check it out and see if they are needed.

My best guess is that this is the result of remodeling in the past, and all those boxes are being used as junction boxes to extend or splice various circuits. I expect that they are live, and that simply removing them will knock out several electrical circuits, or parts of circuits, as well as presenting code violations if the wires aren’t terminated properly.

I suggest you get an electrician involved before you have a mess on your hands.

@Jean Yes, the wires are hot and the plug is not.

@Bruce in Northern Virginia No, I can't see anything from the box. From what I can see there's not fan. Or maybe there is and I don't know where to look. I own a voltage tester. The cords are hot, but the plug is not. They've also be tested with an outlet tester. Didn't think about going to the breaker box. Thanks!

@cat_ky Oh I'm not doing it myself that's for sure.

@kudzu9 Yes, there are live. Don't worry. I definitely won't be trying to remove them myself. Thanks!

I would replace the cover & forget about it.

Or go into the attic and looks for where the black cord comes thru the plate. It could be feed for a light. But the cord looks heavy duty so I suspect it terminates/ or teminated at a fan or other kind of ventilator. Might just be an extension cord that is routed to the attic. Or it could be the feed for a receptacle in the attic--obviously not an up to code situation. But possible. This is an exterior wall, correct? It could terminate in the eave and be the power source for Christmas lights,

I suspect the black cord with a plug would be illegal if it runs through a wall or floor.

How did you determine the cords are hot but the plug is not? Plug-in outlet testers are reliable, but non-contact tester (they often look like a big pen) frequently show false voltage readings.

Black 120 volt cord in the wall would be a code violation (cordage running through a wall. It sounds like you need an electrician to sort this out.

Bruce