Answer / bipin kumar mishra

earth resistance can measure by earth testor/earth resistor.

Answer / ravindra

earth resistance is measured by earth tester

Answer / naveen kumar mishra(03\08\1987

the most easy to calculate the specified earth
resistance,is by using earth testor.
a earth testore is a electric generator which generate the
electric voltage as per constant speed of that rotor
(generator).
if any low resistance load will apply across that voltage
so an electric current will also generate.
by this current,and voltage,we can calculate the value of
applied load resistance.
so lets assume----------
the voltage value generated by earth testor

is = V volts,

and current value is = I amp

so according ohms law

the applied load value will(earth resistance) = R

SO R =V/R ohms.

Answer / ssreenu

Mr. Dinesh, please tell me at what distance(min & max) the
spikes to be placed from earth electride and how much
distance(min and max) should be kept between the earth
spikes?

Answer / rajkishore parida

Visit the website
http://www.kilowattclassroom.com/Archive/AN0009.pdf - 91k -
This is the best site where one can get the best answer on
how to measure the earth resistance and all the related
information.

Answer / yogesh

the current being supplied from the AC power lines.
Alternatively, a bridge may be
used for measurement. Most often, the ground resistance is
measured with selfcontained
instruments such as the Megger ground resistance Tester.
The resistivity of earth may vary over extremely wide
limits, depending on the
composition of the soil and the moisture content.
Representative values are:
General average 100 ohm-meters
Swampy ground 10-100 ohm-meters
Sea water 0.01-1 ohm-meters
Dry earth 1000 ohm-meters
Pure slate 107 ohm-meters
Sandstone 108ohm-meters
Fig. 2 Equivalent radius A of groups of ground rods of
radius "a"
I current
V voltmeter
Ground under test Reference ground Auxiliary ground
Fig. 3 Fundamental method of ground resistance measurement
TYPE 3235 Earth TESTER
Adequate earthing systems for telecommunications,
electronic and electrical
equipment, power lines and lightning arresters of steel
towers and high buildings are
of extreme importance. Good earthing systems safeguard
personnel and equipment
during fault conditions. They are also frequently necessary
in minimising electrical
noise and for normal, reliable operation of electrical and
electronic equipment. The
resistance of any earthing system should be periodically
checked to ensure that it is
within limits.
The Type 3235 Earth Tester can be used to check almost any
earthing system. It
incorporates a test for earth voltage. AC voltage up to 30V
may be measured. High
S S S
S S S S
A=SQRT(a S ) S
A= cube root of(aS2) A= fourth root of(sqrt(2)aS2)
S

Answer / s. ghosh

earth resistivity is measured by earh megger . there so
many methods of earth resistivity measurements like1)
wenner 4 pin method, 2) schlumberger method, 3) driven rod
or 3pin method. all those test results varies on different
parameters of the site. to minimise tose effects the tests
has to be performed in an arrey called"line traverse
servay". the detail of those above methos i.e. the distace
of rod depth of rod and their variation is to be discussed
in detail. however the result given by the "earth megger"
i.e. the resistance of earth is to be converted into earth
resistivity by the following formula.
Wenner method:-
r(resistivity) = 2(PI)A R : A =Probe spacing, R
resistance reading in the E/megger
Schlumberger:-
r=(PI) L.L.R/2.l L=centre limb to outer probe,
l=centre limb to inner probe,
Driven rod:-
r=2(PI)lR/Ln(8l/d) l=rod length in earth, d=dia of rod.
contact me at sgmanofpower@yahoo.com if you have got
further details or questions.

Answer / zeenath

s i do...it should be less than 1 ohm..for any
clarification plz call me at 09036571568..

Name: Zeenath Kundur
Mobile: 09036571568
Official ID : zeenath.kundur@prithvisolutions.com

Thanks and Regards,

Zeenath Kundur
Project Manager
Prithviinformation Solutions LTD

Answer / nurul islam mallick

The Fluke 1625 earth ground tester is able to measure earth ground loop resistances for multi grounded systems using only current clamps. With this test method, two clamps are placed around the earth ground rod or the connecting cable and each are connected to the tester. A known voltage is induced by one clamp, and the current is measured using the second clamp. The tester automatically determines the ground loop resistance at this ground rod.



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 recommended 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 sensitive equipment it should be 5.0 ohms or less.”

The Telecommunications industry has often used 5.0 ohms or less as their value for grounding and bonding.

The goal in ground resistance is to achieve the lowest ground resistance value possible that makes sense economically and physically.

Answer / tofan kumar sahu

Earth resistance should be mesured only by using earth
tester the potential spike must be placed minimum 10mtr
away from mesuring earth pit & auxulary spike must be
placed minimum 10mtr from potential spike.That means the
distance between 2 spikes +the distance between earth pit &
potential spike should not less than 20mtr.

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