BS 7671 Table 54G indicates Earth cable sizing for Power cable size.
If the Electrical Sub Panel is far away & local earth electrodes (Eart Pit) is provided, is it medatory to run earth continuty conductor with the cable feeding to Sub Panel
To decide if the PE cable should be run to a far Sub-Panel or not, we should know the used ” Earthing System ” for the project. For exp. in ” TT system ” it shouldn't be, because in this sytem we can use 2 or more different earth electrodes, but in ” TN-C & TN-S ” it should be, because we can't use more than one earth electrode.
By the way be carful if you are using ” TT ” that means at least 2 different earth electrods, these 2 different earth electrods shouldn't be connected, because when we connect them the earthing system will ” TN “.