Which type of attachment fitting must be used with a box equipped with a hub for a pendant box?

The correct choice focuses on the requirement that any attachment fitting used with a box equipped with a hub, particularly for pendant applications, must be listed. This listing indicates that the fitting has been tested and meets the necessary standards for safety and performance as specified by the National Electrical Code (NEC).

In applications involving pendant boxes, which typically support fixtures hanging from a ceiling, it is crucial to use fittings that have been specifically tested for this purpose to ensure they can adequately support the weight and electrical components while minimizing risks such as electrical failure or mechanical failure.

By using a listed fitting, you are ensuring that the product has undergone rigorous testing and has been found compliant with relevant safety standards, which is essential for both the safety of the installation and the integrity of the electrical system.

Other options do not adequately reflect the necessary standards required for safe electrical installations. For instance, standard fittings may not have been evaluated for the specific application, while universal and adjustable fittings don't necessarily mean they have been tested for safety and might not meet code requirements for pendant applications. Thus, the use of a listed attachment fitting is the best practice when working with a pendant box equipped with a hub.