Why does my garage have a wire coming out of it to the outside wall and hangs on a wood trellis?

I just got a house and the detached garage has a 240V outlet inside it. On that wall of the outlet, on the outside, there is a wire that is coming out and it is attached to a wood trellis (for flowers). Did they do this to make sure the outlet is grounded? Does this mean that the outlet itself is not a good... show more I just got a house and the detached garage has a 240V outlet inside it.
On that wall of the outlet, on the outside, there is a wire that is coming out and it is attached to a wood trellis (for flowers).

Did they do this to make sure the outlet is grounded?
Does this mean that the outlet itself is not a good outlet? Or is it just a precaution, like a back up?
Update: I did have a licensed home inspector do an inspection before I bought the house. He never mentioned the wire. I found it months later. It seems like it is just for backup because there is a 240v outlet in the garage and maybe the wire is just extra security. The outlet is grounded. But then I saw the wire, so... show more I did have a licensed home inspector do an inspection before I bought the house. He never mentioned the wire. I found it months later.
It seems like it is just for backup because there is a 240v outlet in the garage and maybe the wire is just extra security. The outlet is grounded. But then I saw the wire, so wondered what it was for.
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