Not a separate circuit, for safety reasons, the ground wire between outlets are connected in parallel.
In the safety of electricity in the common sense, more than one outlet can not be connected to only one ground wire, then there is no ground wire socket if the leakage, it can only rely on the use of electrical appliances in series with the phase or zero wire can be connected to the ground.
In order to safe electricity, the purpose is in the socket maintenance, not to remove the grounding wire when the grounding wire is disconnected from other sockets, to ensure that other sockets of the grounding wire can play a role in safety protection.
Extended information:
1, personal safety protection: due to electrostatic discharge, it is easy to generate a large number of charges. The role of the grounding wire happens to be the wire connecting the high-voltage equipment and the earth, which plays a role in avoiding us from being damaged by the electric charge.
2, lightning protection: in the past in thunderstorms, utility poles and other equipment is often damaged by lightning, sometimes even up to several days, so the role of the grounding wire in the lightning protection can play a very good role in protecting and effectively extend the service life of electrical equipment.
3, to ensure normal operation: for some work that can only be carried out with electricity, such as medical work, the role of the grounding wire is to avoid sudden power outages, will not be affected, and can still be used as a reference potential for small loads to operate normally.