On which device does leakage current flow through the ground conductor during normal operation?

The correct answer is found in the concept of grounding and the safety mechanisms designed to redirect leakage current. A three-prong power cord device is equipped with a ground conductor that helps protect users from electric shock by providing a safe path for any leakage current that may occur during normal operation.

In the event of an internal fault or insulation breakdown, the current that inadvertently flows to the exterior or metallic parts of the device is directed to the ground through the ground prong of the three-prong plug. This not only helps in preventing electric shock to users but also facilitates tripping of circuit breakers or ground fault circuit interrupters, which further enhance the safety of the electrical system.

Conversely, devices that utilize two-prong power cords lack this essential grounding feature, which means they do not have the capability to safely handle leakage currents that might develop. Therefore, without the grounding mechanism, any leakage current could pose significant safety hazards. Thus, the three-prong power cord device is specifically designed to manage leakage currents effectively, making it the correct answer in this context.