Revit MEPUse this tool to indicate the panel from which a circuit originates. Power circuits can only be connected to a compatible panel. The panel being selected must have a slot available, and must match the distribution system for the circuit being connected.
System Tools panel
Edit Circuit, and select a panel in the drawing or on the Options Bar, select a panel from the Panel drop-down. The list contains only compatible panels, ordered according to their distance from the circuit (closest at the top of the list). You can also select a panel by selecting a panel in the drawing area.