Joe brings up a good question. What constitutes "Engineering Supervision"?

Every project I work on here at work is under the direction of a Registered Professional Engineer. I call that engineering supervision. However, if I were out there pulling wires, etc. as some of you are, then what is engineering supervision? Inspectors aren't required to be Registered Engineers in this state, perhaps in other states. As a field person, do you need to hire an engineer when necessary? How do you confirm that you have done so? Does the engineer sign off on something?

Just a few questions that come to mind.