Which part of a subpanel in a residential installation is supposed to be isolated?

In a residential subpanel, the neutral bar is the component that needs to be isolated from the grounding system. This is necessary to prevent neutral current from flowing on the grounding conductors, which can create potential safety hazards, including electric shock risks and interference with equipment operation.

Isolating the neutral ensures that the return path for electrical current remains balanced and that any ground-fault protection devices can operate correctly. In a main panel, the neutral and ground are bonded together, but in any subpanel downstream from the main panel, they must be kept separate. This approach helps maintain proper ground fault protection and system integrity.

The grounding terminal, in contrast, is designed to connect to the earth and provide a safe path for fault current. Keeping this connection intact is crucial for safety and system operation. Therefore, while both components play vital roles in electrical safety, only the neutral bar requires isolation in the context of a subpanel.