Is this a ground cable coming into old panel?

[Fee]

I am doing a demo and renovation on a bathroom. I found a hidden panel behind tile and need to move it to the attic, which isn’t a problem. But in the panel there is this bare wire connecting to what looks like a grounding bar and the wire extends down through armored cable into the finished basement. There is a mix of NM and AC wire in emt conduit coming into the panel. What is this and does it impact me moving the wires to a new box in the attic?

 

[piglet11]

Bit late to the party

It's USA practice but best bet is disconnect one end at a time and check continuity.

All the metal parts should go back to a secure ground and that might be at the utility incomer, possibly an earth rod or the neutral if it's a PME system.

An installation tester and a long test lead would help.

Can't tell anything from the photos.

Take care.