When you do construct your roof for your pen you will make to make sure the wire is maintained well, no loose ends, and overly saggy parts.
There was an incident here in fife not that long ago, where a sea eagle got into a pen of geese through an old faulty wire pen roof and became trapped, i think it did kill a goose before realising it was trapped then went into a state of panic, then the goose owner released the eagle the panic stricken bird flew straight over his head, but it's talons clipped causing a few fairly bad cuts!! the sea eagle flew into the side of a barn knocking itself out, and was then removed by trained RSPB officials - sadly this sea eagle collided with a train not long after re-release
the rspsb did relplace the wire on the whole run as compensation, but in my opinion the wire should have been fit for purpose!.