Can anyone tell me what the requirements are regarding visual inspections on earth sources, ie rods/conductive concrete etc? The scenario Ive got is that the original earth was a rod however it appears as if conductive concrete was installed subsequently but theres no documentation to support this. Theres a 16mm cable coming out of the ground which has all the characteristics of conductive concrete but Ive got no way of proving this. Please help as the original earth rod is no good anymore.