Gridlines between empty Curtain panels...visible?

[gsucci]

Hi all,
I have some curtain panels set to system empty panels, no mullions between them, but the gridlines become solid black thin lines, and they are visible everywhere.
In other words, the panels are empty, but there is this kind of model line at the curtain wall gridline, which shows like a cable in every view...
I can pick it with the line tool and make it invisible, but I have a lot of these lines around...

Is there a way to turn those lines off, in some visibility setting?
Why are they showing, in the first place?

thank you

regards

gio

[gsucci]

Nevermind, the family for the system empty panel had one of the lines set to panel projection instead of invisible line...

Thank you