In a family, place a connector on a face or on a work plane.
3D Views
3D, and spin the model to view the face where you want to place a connector.
The first connector that you place for a specific type is assigned as the primary connector. You can change the assignment later.
Connectors panel, and click a connector type, such as Duct Connector.
The primary connector is placed.

The sizes and orientation that you specify determines how connections are made with compatible components. You can enter parameter values or associate them with family parameters for the component.
The first connector that you place for a specific type is assigned as the primary connector. You can change the assignment later.
Connectors panel, and click a connector type (Electrical, Duct, Pipe, Cable Tray, or Conduit).
For example, click Electrical Connector, and click Modify | Place Electrical Connector tab
Placement panel
(Work Plane).
In this example, an electrical connector is placed on the top work plane of a junction box.

You can enter parameter values or associate them with family parameters for the component.