aw per IS it should not be more than 1 ohm.

For 1 kv to 33 KV The earthing Resistance Should be less 
than 0.5 ohm.
For Domestic Purpose it should less than 2 ohm
Upto 1 Kv It should be in between 1 to 2 ohm 
for EHV it should be  less than 0.01 ohm

hor residential area the earthing resistance should be less 
than 1 ohm.
for substation of capacity less than 33 kv the resistance 
in between 1-3 ohm.

according to IEEE maximun value of earthing can be 5
ohms.But for a substation it should be less than 2 ohms.

For residential it should be below 1 ohms. For EHV stations 
and constructions it should be maintained below 0.5ohms. 
And for LC systems it should be maintained below 5 ohms.