Answer / rkshjangra

For large power station = 0.5
for small substation = 2.0
for domestic wiring = 5.0

Answer / jayantlande3

It should be less than one ohm.

Answer / p.gupta.1852

Earth resistance should be as small as possible . It
depands on voltage level of the system to be grounded . As
voltage level increases the earth resistance required to be
nearer to zeero as far as possible . Earth resistance
should not exceed 5 ohm for 433V distribution system and
should be below 1 ohm for 66 KV Grid .

Answer / preethi

may be earth resistance value is considered as ideally zero.but it is mostly less than 1 ohm.

Answer / mahesh babu-calicut

the earthing resistance of any electrical system should be
below 5 ohms,unless otherwise specified

Answer / raj kumar

for large power s/s =.5
for small sub s/s =2.0
for domestic = 5.0

Answer / d m chudasama

it depends upon eath compositon. But shoud be normally less then 5 ohms.

Answer / rajkumar.d

There is a good deal of confusion as to what constitutes a
good ground and what the ground resistance value needs to
be. Ideally a ground should be of zero ohms resistance.

There is not one standard ground resistance threshold that
is recognized by all agencies. However, the NFPA and IEEE
have recom- mended a ground resistance value of 5.0 ohms or
less.

The NEC has stated to “Make sure that system impedance to
ground is less than 25 ohms specified in NEC 250.56. In
facilities with sen- sitive equipment it should be 5.0 ohms
or less.”

Answer / dk gnfc

Without grid: <1
With grid:<5

Answer / guest

it should be 0.5 ohms

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