Which of the following configurations is permissible for service entrance conductors in multiple occupancy buildings?

In multiple occupancy buildings, the installation of service entrance conductors must comply with the National Electrical Code to ensure safety and proper functionality. The correct configuration for service entrance conductors where one shared set is used for common circuits makes sense from both a practical and regulatory standpoint.

By utilizing one shared set of conductors for common circuits, the system can efficiently provide power distribution to multiple units while minimizing redundancy and unnecessary complexity. This approach allows for the efficient use of space and resources, as a single set of conductors can manage the electrical demands of shared services, like lighting for hallways, intercom systems, and other common areas.

Moreover, this configuration likely helps reduce the overall wiring costs and simplifies the installation and maintenance processes since one set of conductors is easier to manage compared to multiple separate installations. The National Electrical Code allows for flexibility in design while ensuring safety and effectiveness in meeting the electrical needs of a building with multiple tenants.

In this context, the other configurations suggested do not align with typical practices or NEC guidelines for service entry in multiple occupancy buildings. For instance, separate conductors for each unit could lead to inefficiency, and having three sets for redundancy may not be warranted or practical in most scenarios. Thus, the shared configuration is both permissible