6% voltage drop for 60 amp sub panel?
you've got to clip it nice and neat or else it won't pass inspection. Best to call your inspector and have them tell you what they want to see. The do make clips to fasten the wire. any electric supply should carry them.
Sarcasm is my friend
I'm here to learn too, i do mostly commercial/industrial/new construction and this place is a great way to pick up tips on residential from some good electrical minds. Excuse the spelling, my phone has a mind of it's own.