Electrical wire sheathing should not project more than about 1 inch into the?

Question

plumbing line , floor joist, electrical panel, ground

Answer 1

"electrical panel" is the only one that makes any sense. I assume you are talking about the outer jacket on something like "Romex®" or other nonmetallic sheathed cable, usually with metallic sheathed cable e.g BX the sheathing terminated at the box connector and doesn't enter the panel (or other enclosure) at all.

Answer 2

Ground

What are you doing, taking a NEC refresher test?

FYI: It is not allowed to use water pipe for electrical raceway. A floor joist can be used to support metalic and non-metalic raceway not wire. A ground wire must be connected to an appropriate Ground Rod within 6ft of the entrance. And the wire sheathing should always be carried into an electrical panel otherwise you could cause a short between non-grounded wires.