Approved plans (by Twp after Plan Review) must be on the jobsite at all times when inspections are being performed.
As Greg said, there is a stamp placed on the plans that the various disciplines (Elec/Plum/Bldg/Fire) initial & date upon Plan Review for code compliance.
Approved plans not being on site for reference by any of the inspectors results in 'no inspection being performed' (Red Tag)
