When is a cable assembly shield permitted to serve as the required equipment grounding conductor?

A cable assembly shield is permitted to serve as the required equipment grounding conductor when it is of the concentric strand or conductive tape type. This is because these types of shielding are designed to effectively conduct electrical current and provide a reliable path for ground faults. They are specifically constructed to ensure good electrical contact and low resistance, which is crucial for grounding applications.

The concentric strand and conductive tape types allow for sufficient surface area contact, which is essential for both safety and optimal performance in grounding scenarios. This use of shielding as a grounding conductor is recognized in industry standards, given their adequate electrical properties.

In contrast, other types of shielding, such as ribbon-type shields, may not provide the necessary electrical conductivity or surface area to effectively perform as a grounding conductor and are therefore not permitted for this use. While metal types generally offer good conductivity, not all metal types are approved for grounding purposes; it depends on their construction and application context. Low-voltage applications may have different requirements and are not inherently linked to the ability of a cable assembly shield to function as a grounding conductor.