Earthing

I.E. Rules 61  :   substation and equipments

I.E. Rules 67 : HV and EHV

Maxm Res. :
Large power stations   0.5 ohms
Major Substations      1.0 ohms

Small Substations    2.0 ohms
Others                       8 ohms


I.E. Rules  1956 Chapter I 

Low :          250 V
Medium:    650 V
HV:           11 KV
EHV:         33 KV