Earthing and protective conductors should comply with BS 7430, BS EN 50522 and BS 7671. HV generators will be earthed (neutral-earth resistor or earthing transformer considered), and generator earthing should ensure fault current adequate to operate protective devices anywhere in the network. Interconnecting HV and LV earths needs modelling of ground potential rise, disconnection times, touch and step voltages and stress voltage by the designer or an independent specialist, with measured soil resistivity and two-layer analysis. Every LV switchroom should have a visible bare copper earth bar with all switchgear bonded to it.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.