The Swap Feeder command is used to transpose two parallel feeder segments on the one-line diagram.
To swap feeders, go to
Ribbon: DM Electrical->One-Line Diagram-> 
Swap Feeder
Pulldown Menu: DM Electrical->One-Line Diagram->Swap Feeder
You will be prompted to select a feeder segment.
Select first feeder segment to swap:
You will then be prompted to select a feeder segment to transpose with the first feeder segment.
Select second feeder segment to swap:
The two feeder segments will be transposed. The other segments of each feeder will be redrawn if necessary.