The Connect Distribution Equipment on One-Line Diagram command is used to connect distribution equipment that has been inserted on the one-line diagram.
To connect distribution equipment on the one-line diagram, go to
Ribbon: DM Electrical->One-Line Diagram-> 
Connect Distribution Equipment on One-Line Diagram
Pulldown Menu: DM Electrical->One-Line Diagram->Connect Distribution Equipment on One-Line Diagram
You will be prompted to select the device to be connected. This device is the downstream distribution equipment that is further from the utility. This device is also commonly called a sub-feed panel or a sub-panel.
Select downstream equipment to connect:
You will then be prompted to select the device to which the first device will be connected. This device is the upstream distribution equipment that is closer to the utility.
Select upstream distribution equipment to connect to:
After you make your selections, the Distribution Equipment Connection dialog box will appear.
Distribution Equipment Connection Dialog Box
Top Lugs: This selection is available for panels, switchboards, breakers, disconnects, and transfer switches that have their Lugs set to DOUBLE.
Feedthrough: This selection is available for panels, switchboards, breakers, disconnects, and transfer switches that have their Lugs set to FEEDTHRU.
Breaker / Tap: All devices will allow you to select Breaker / Tap as the connection type. Select the breaker or tap to connect to using the Odd Breakers / Taps or Even Breakers lists.
Odd Breakers / Taps: For panels, a list of the odd breakers. For all other distribution equipment, a list of all of the taps. The breaker or tap selected in this list will be used for the connection. If an Even Breaker is selected, the top blank entry will be selected in this list.
Even Breakers: For panels, a list of the even breakers. Not used for all other distribution equipment. The breaker selected in this list will be used for the connection. If an Odd Breaker is selected, the top blank entry will be selected in this list.
Change Number of Poles: Press this button to open the Change Number of Poles dialog box and change the number of poles of the currently selected circuit. This dialog box can be used to convert two-pole and three-pole circuits to multiple single-pole circuits. See the Change Number of Poles section for more information.
Feeder Connection Drafting Style: Whether the feeder connecting the selected devices is drawn in a one-line configuration or a riser configuration.
Press the Connect button to make the connection.