Which component is commonly part of an underground cable insulation system?

• A. Jacket
• B. Shield
• C. Insulation
• D. Polyethylene

Answer: (C)

The essential idea is recognizing what provides electrical isolation in an underground cable. The insulating layer around the conductor is the part whose job is to prevent current from leaking to soil or to other conductors by creating a dielectric barrier that withstands voltage and moisture. While jackets protect the cable externally and shields can reduce electromagnetic interference or carry fault current, they are not the insulating function. Polyethylene is a common material used to make insulation, but the component that forms the insulation system itself is the insulation layer.