Ground wires should not carry current under normal circumstances. The ground system, including its wires, is (first of all) a safety system.
Bonding neutral to ground in the appliance, or in the receptacle (even having neutral and ground conductors, or using the ground wire as neutral-ground) will cause current circulation through the ground wire and could become a real hazard if the neutral-grounding circuit is interrupted (the chassis of the appliance could be “hot” now).
Joe.-
