Is a metallic insulation shield encircling current-carrying conductors allowed to serve as an equipment grounding conductor?

A metallic insulation shield encircling current-carrying conductors can serve as an equipment grounding conductor if it is appropriately rated for that purpose. This is because the shield, being metallic, has the ability to provide a low-resistance path to the ground, which is essential for safety during fault conditions. If the shielding is designed and tested to meet the necessary electrical and mechanical standards, it can effectively conduct any fault currents safely to ground, thus helping to prevent electrical shock hazards and equipment damage.

When determining if a metallic shield is suitable as a grounding conductor, factors such as the material, thickness, and integrity of the shield, as well as its continuity and connections to ground, must be considered. Various codes and safety regulations specify the conditions under which such a shield can be used, reinforcing the importance of ensuring that these parameters are met.

While the possibility exists that there are situations or specific applications (as mentioned in other choices) where it may not always be applicable, the fundamental principle is that a properly rated metallic shield is indeed permissible to serve as an equipment grounding conductor.