underground connections need cable guard (conduteur earth)?

[Ennajjar]

Hello
in underground connections you need a cable guard (conduteur earth) or not? Why

 

[Supertester]

A ground conductor allows fault voltage to trip the protection device, other wise a dry earth environment may allow the fault to remain energized and dangerous. When fault locating a cable fault it is nice to have a ground reference so you can use a time domain reflectometer to relocate the fault. When locating the fault, the ground conductor keeps the fault locating currents in the cable rather than creating a touch potential in the area of the cable fault.