Advice required on the connection of a mobile standby generator. We have a sub station with a LV Earth to which the star point of thesupply transformer is connected. The supply to is 415V 3-phase + Neutral. Also connected to the LV earth is the earth bars & metalwork of the LV switchgear. We have a separate earth for the HV switchgear metalwork. We have a connection point for connecting a standby mobile generator when required, and this connects to our LV board and supplies power by way of a changeover switch. This is interlocked with the mains supply so that only one source can be on at any one time. Now we have had a visit by some copper thieves and all the earthing has been nicked. I am in the process of installing the earths again, but not quite sure what to do with the generator earth. I thing I'm right in saying that a standby generator should have its own independant earth, but I am concerned that this will get nicked again. What I'm thinking of doing is running an earth connection from the generator point to the LV earth inside the sub. If I need to connect a generator to supply standby power if mains power is off, then the generator earth would be connected to the LV earth, and I would remove the link connecting the transformer neutral point to the LV earth. Replacing this link and disconnecting the generator when mains is to be restored. Is this OK?