In which scenario can Class 1 circuits share a cable with power supply circuits?

Class 1 circuits can share a cable with power supply circuits when they are functionally associated with the equipment powered. This means that the Class 1 circuit is integral to the operation of the electrical system, ensuring that both circuits work together to facilitate the function of the equipment they serve.

The National Electrical Code (NEC) recognizes the importance of proximity and association between power and low voltage communication systems, allowing for their co-installation in single pathways when they have a direct interrelationship. This allows for the safe and efficient distribution of power and data, as both circuits can communicate effectively without interference, while staying compliant with regulatory standards.

The other scenarios listed do not support the necessary functional association required for such installations. For instance, geographical separation, such as being in different buildings or installed underground, does not guarantee that the circuits would work together properly since they are not related by their function. Likewise, the length of cable does not inherently determine whether Class 1 circuits may share a cable with power circuits; rather, it is the operational relationship between the systems that primarily governs such decisions.