A leg refers to one distinct phase conductor in a multi-phase power circuit, or one side of a split-phase system. In a three-phase system, technicians refer to the individual phases as legs. It is used to describe how loads are distributed or where a specific measurement is taken.
We lost the B leg on that transformer, so it's single-phasing the motors downstream.
Balancing the load across all legs is critical to prevent neutral current overload and transformer overheating.
Related terms
Phase
A single distinct oscillating voltage or current in a multi-conductor electrical system.
Single-phasing
A destructive fault condition where a three-phase motor loses one of its supply phases.
Split-phase power
A single-phase distribution system that provides two separate voltages using a center-tapped transformer.