During what condition does the Equipment Grounding Conductor carry current between the two panels?

The Equipment Grounding Conductor (EGC) is specifically designed to provide a safe path for electrical current in case of faults, such as during a ground fault condition. A ground fault occurs when there is an unintended path for current to flow to the ground or to a conductive surface that can cause shock hazards or fire. Under these circumstances, the EGC carries the fault current back to the source to ensure that overcurrent protection devices, like circuit breakers, can trip effectively and disconnect the power.

In normal operation, the EGC does not carry current, as it serves primarily as a safety feature rather than a conductor for standard operation currents. Similarly, while a short circuit can cause excessive current to flow through energized conductors, the EGC’s role is less significant in this scenario compared to when a ground fault occurs. Thus, the EGC primarily operates under ground fault conditions to facilitate a safe disconnection and prevent dangerous situations.