A Loop occurs when a conductor feeds back into itself. In the following image, the Loop is highlighted in orange.
Loops can cause problems such as indeterminate flow with ArcMap's native tracing tools. However, ArcFM traces (upstream and downstream) utilize Feeder Manager to identify loops in the network. If any paths discovered by the ArcFM traces contain features belonging to an electrical Loop, then all features in the loop will be included in the results.