If an appliance cord has a grounding conductor, what is the effect of grounding the outlet boxes?

Grounding the outlet boxes serves to provide an additional safety measure for electrical systems. When an appliance cord has a grounding conductor, it is designed to ensure that any fault current—such as a short circuit—can safely return to the ground. By grounding the outlet boxes, it effectively establishes a path for this fault current, thereby grounding the appliance or equipment connected to the outlet.

This grounding facilitates the safe operation of electrical devices by reducing the risk of electric shock or fire. If the appliance were to develop a fault and cause current to leak to the chassis or casing, the grounding conductor would direct that current safely away, triggering the circuit breaker or fuse to cut off the electrical supply. This design is crucial for maintaining safety in any electrical installation, as it mitigates the potential dangers associated with electrical faults.