What must be ensured about the sheathing of conductors in intrinsically safe circuits?

In intrinsically safe circuits, the sheathing of conductors plays a critical role in ensuring safety and functionality in hazardous locations. The correct answer emphasizes the importance of the conductors being able to safely carry fault current to ground. This is crucial because if a fault occurs, the resulting current could potentially ignite flammable materials in a hazardous environment. Therefore, the sheathing must be designed to manage and redirect this current safely, preventing any risk of explosion or fire.

The requirement for the sheathing to carry fault current is part of a larger strategy to maintain the integrity of the intrinsically safe circuit. It supports the principle that, even in the event of a fault, the system remains safe and does not lead to ignition sources that could cause an explosion.

In contrast, options that suggest the sheathing must be non-grounded, of any type, or insulated from all other devices do not meet the critical safety standards established for intrinsically safe circuits. A non-grounded sheath may lack a safe path for fault currents, while an unrestricted choice of sheath type might not provide the necessary protection. Furthermore, insulation from all other devices could compromise the ability to effectively manage any fault conditions that may arise, leading to potential safety hazards.