Earthing and Electrical Grounding Installation

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Earthing and Electrical Grounding Installation | A Complete Guide

What is Grounding or Earthing?

To connect the metallic (conductive) Parts of an Electric appliance or installations to theearth (ground) is called Earthing or GroundingIn other !ords" to connect the metallic parts of electric machiner# and devices to theearth plate or earth electrode (!hich is $uried in the moisture earth) through a thic%conductor !ire (!hich has ver# lo! resistance) for safet# purpose is %no!n as Earthingor groundingTo earth or earthing rather" means to connect the part of electrical apparatus such asmetallic covering of metals" earth terminal of soc%et ca$les" sta# !ires that do not carr#current to the earth Earthing can $e said as the connection of the neutral point of apo!er suppl# s#stem to the earth so as to avoid or minimi&e danger during discharge ofelectrical energ#
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Good to know

Difference between Earthing, Grounding and Bonding.

'et me clear the confusion among earhing" grounding and $onding

Earthingand Groundingis the same terms used for earthingGrounding is the

commonly wordused for earthing in the North Americanstandards li%e IEEE, NEC,

ANSIand ULetc !hile" Earthing is used in European" Common !ealth countries

and Britain standards like IS and IECetc

The !ord Bondingused for ointing t!o !ires (as !ell as conductors" pipes or

appliances together onding is %no!n as connecting the metallic parts of different

machines !hich is not considered to $e carr#ing electric current during normal operation

of the machines to $ring them at the same level of electric potential

Need of Earthing or Grounding. Why Earthing is Important?

The primar# purpose of earthing is to avoid or minimi&e the danger of electrocution" fire

due to earth lea%age of current through undesired path and to ensure that the potential

of a current carr#ing conductor does not rise !ith respect to the earth than its designed

insulation

When the metallic part of electrical appliances (parts that can conduct or allo! passage

of electric current) comes in contact !ith a live !ire" ma#$e due to failure of installations

or failure in ca$le insulation" the metal $ecome charged and static charge accumulates

on it I! a person touches such a charged metal " the result is a severe shoc%

To avoid such instances" the po!er suppl# s#stems and parts of appliances have to $e

earthed so as to transfer the charge directl# to the earth

Below are the basic needs of Earthing.

To protect human lives as !ell as provide safet# to electrical devices and appliances

from lea%age current

To %eep voltage as constant in the health# phase (If fault occurs on an# one phase)

To Protect Electric s#stem and $uildings form lighting
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To serve as a return conductor in electric traction s#stem and communication

To avoid the ris% of fire in electrical installation s#stems

Different Terms used in Electrical Earthing

Earth"The proper connection $et!een electrical installation s#stems via conductor to

the $uried plate in the earth is %no!n as Earth

Earthed"When an electrical device" appliance or !iring s#stem connected to the earth

through earth electrode" it is %no!n as earthed device or simple *Earthed+

Solidly Earthed" When an electric device" appliance or electrical installation is

connected to the earth electrode !ithout a fuse" circuit $rea%er or resistance,Impedance" It is

called *solidl# earthed+

Earth Electrode" When a conductor (or conductive plate) $uried in the earth for

electrical earthing s#stem It is %no!n to $e Earth Electrode Earth electrodes are in different

shapes li%e" conductive plate" conductive rod" metal !ater pipe or an# other conductor !ith

lo! resistance

Earthing Lead- The conductor !ire or conductive strip connected $et!een Earth

electrode and Electrical installation s#stem and devices in called Earthing lead

Earth Continuity Conductor" The conductor !ire" !hich is connected among different

electrical devices and appliances li%e" distri$ution $oard" different plugs and appliances etc in

other !ords" the !ire $et!een earthing lead and electrical device or appliance is called earth

continuit# conductor It ma# $e in the shape of metal pipe (full# or partial)" or ca$le metallic

sheath or fle.i$le !ire

Su# $ain Earthing Conductor- A !ire connected $et!een s!itch $oard and distri$ution

$oard ie that conductor is related to su$ main circuits

Earth %esistance" This is the total resistance $et!een earth electrode and earth in /

(0hms) Earth resistance is the alge$raic sum of the resistances of earth continuit# conductor"

earthing lead" earth electrode and earth

POINTS TO BE EARTHED

Earthing is not done an#ho! According to IE rules and IEE (Institute of Electrical

Engineers) regulations"

Earth pin of 12pin lighting plug soc%ets and 32pin po!er plug should $e efficientl# and

permanentl# earthed

All metal casing or metallic coverings containing or protecting an# electric suppl# line or

apparatus such as GI pipes and conduits enclosing 4I5 or P4C ca$les" iron clad s!itches"

iron clad distri$ution fuse $oards etc should $e earthed (connected to earth)
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The frame of ever# generator" stationar# motors and metallic parts of all transformers

used for controlling energ# should $e earthed $# t!o separate and #et distinct connections

!ith the earth

In a dc 12!ire s#stem" the middle conductors should $e earthed at the generating

station

6ta# !ires that are for overhead lines should $e connected to earth $# connecting at

least one strand to the earth !ires

Components of Earthing System

A complete electrical earthing s#stem consists on the follo!ing $asic components

Earth Continuity Conductor

Earthing Lead Earth Electrode


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Components of Electrical Earthing System

Earth Continuity Conductor or Earth Wire

That part of the earthing s#stem !hich interconnects the overall metallic parts ofelectrical installation eg conduit" ducts" $o.es" metallic shells of the s!itches"

distri$ution $oards"6!itches" fuses" 5egulating and controlling devices" metallic parts of

electrical machines such as" motors" generators" transformers and the metallic

frame!or% !here electrical devices and components are installed is %no!n as earth

!ire or earth continuit# conductor as sho!n in the a$ove fig
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The resistance of the earth continuit# conductor is ver# lo! According to IEEE rules"

resistance $et!een consumer earth terminal and earth Continuit# conductor (at the end)

should not $e increased than 7/ In simple !ords" resistance o! earth wire should #e

less than &'

6i&e of the Earth Continuit# Conductor or Earth Wire depends on the ca#le si(e used in

the wiring circuit

Size ofEarth Continuity Conductor

The cross sectional area of the Earth Continuity Conductor should not $e less than

the half of the cross sectional area of the thic%est !ire used in the electrical wiring

installation

Generall#" the si&e of the $are copper !ire used as earth continuit# conductor is 16WGut %eep in mind that" don8t use less than 736WG as earth !ire Copper strip is also

can $e used as earth continuit# conductor instead of $are copper !ire $ut don8t go for it

until manufacture recommend it

Earthing Lead or Earthing Joint

The conductor !ire connected $et!een earth continuit# conductor and earth electrode

or earth plate is called earthing oint or *Earthing lead+ The point !here earth continuit#

conductor and earth electrode meet is %no!n as *connecting point+ as sho!n in thea$ove fig

Earthing lead is the final part of the earthing s#stem !hich is connected to the earth

electrode (!hich is underground) through earth connecting point

There should $e minimum oints in earthing lead as !ell as lo!er in si&e and straight in

the direction

Generall#" copper !ire can $e used as earthing lead $ut" copper strip is also used for

high installation and it can handle the high fault current $ecause of !ider area than thecopper !ire

A hard dra!n $are copper !ire is also used as an earthing lead In this method" all earth

conductors connected to a common (one or more) connecting points and then" earthing

lead is used to connect earth electrode (earth plat) to the connecting point
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To increase the safet# factor of installation" t!o copper !ires are used as earthing lead

to connect the device metallic $od# to the earth electrode or earth plate Ie if !e use

t!o earth electrodes or earth plats" there !ould $e four earthing leads It should not $e

considered that the t!o earth leads are used as parallel paths to flo! the fault currents

$ut $oth paths should !or% properl# to carr# the fault current $ecause it is important for$etter safet#

Size of the Earthing Lead


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The si&e or area of earthing lead should not $e less than the half of the thic%est !ire

used in the installation

The largest si&e for earthing lead is 16WG and the minimum si&e should not $e less

than 96WG If 1:,;91 !ire is used or the load current is


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oth copper and iron can $e used as earthing electrode

The si&e of earth electrode (In case of copper)

6ta# tune

Good to know"

on8t use co%e (after $urning coal in the furnace to emit all the gases and other

components" the remaining 99D car$on is called co%e) or stone coal instead of charcoal

(!ood coal) $ecause it causes to corrosion in the earth plate

6ince" the !ater level is different in the different areas therefore" the depth for earth

electrode installation is also different in various areas ut" the depth for earth electrode

installation should not $e less than 7;ft (1 meter) and should $elo! 7 foot (1;39mm)

from the constant !ater level

$otors" Generator" +rans!ormersetc should $e connected from to earth electrode t!o

different places

Earth Plate or Earth Electrode Size for Small installation


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In small installation" use metallic rod (diameter B


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plate


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2). Pipe Earthing:

A galvani&ed steel and a perforated pipe of approved length and diameter is placed

verticall# in a !et soil in this %ind of s#stem of earthing It is the most common s#stem of

earthing

The si&e of pipe to use depends on the magnitude of current and the t#pe of soil The

dimension of the pipe is usuall# 3;mm (7Fin) in diameter and


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length of the pipe to $e $uried $ut usuall# it should $e 3:Fm (7FFft)


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3). Rod Earthing

it is the same method as pipe earthing A copper rod of 7


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If stranded conductor is used as earth !ire" then clean the end of the strands of the !ire

and ma%e sure it is in the straight and parallel position !hich is possi$le then to connect

tightl# to the !aterman pipe

5). Strip or Wire Earthing:

In this method of earthing" strip electrodes of cross2section not less than


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Earth continuit# conductor !hich is connected to the $od# and metallic parts of all

installation should $e tightl# connected to earth lead

7; At last ($ut not least)" test the overall earthing s#stem through earth tester If ever#thing

is going a$out the planning" then fill the pit !ith soil The ma.imum allo!a$le resistance for

earthing is 7/ If it is more than 7 ohm" then increase the si&e (not length) of earth lead andearth continuit# conductors Leep the e.ternal ends of the pipes open and put the !ater time

to time to maintain the moisture condition around the earth electrode !hich is important for

the $etter earthing s#stem

SI specification for Earthing

4arious specifications in respect to earthing as recommended $# Indian 6tandards are

given $elo! Mere are fe!

An earthing electrode should not $e situated (installed) close to the $uilding !hose

installation s#stem is $eing earthed at least more than 7Fm a!a#

The earth resistance should $e lo! enough to cause the flo! of current sufficient to

operate the protective rela#s or $lo! fuses It8s value is not constant as it varies !ith !eather

$ecause it depends on moisture ($ut should not $e less than 7 0hm)

The earth !ire and earth electrode !ill $e the same material

The earthing electrode should al!a#s $e placed in a vertical position inside the earth or

pit so that it ma# $e in contact !ith all the different earth la#ers

Dangers Of Not Earthing A Supply System

As emphasi&ed on earlier" earthing is provided in order

To avoid electric shoc%

To avoid ris% of fire as a result of earth lea%age current through un!anted path and

To ensure that no current carr#ing conductor rises to a potential !ith respect to general

mass of earth than its designed insulation

Mo!ever" if e.cessive current is not earthed" appliances !ill $e damaged !ithout the

help of fuse in place Nou should note that e.cessive current are earthed at their

generating stations !hich is !h# earth !ires carries ver# little or no current at all It

therefore implies that it is not necessar# to earth an# of the !ires (live" earth and neutral

!ires) contained in a P4C Earthing the live !ire is catastrophic


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I have seen a person %illed simpl# $ecause a live !ire got cut from overhead pole and

fell to the ground !hile the ground !as !et E.cessive current is earthed at generating

stations and if at all the earthing is not efficient due to fault" earth fault interrupters !ill

$e there to help use help onl# !hen the po!er transmitted is a$ove the rating of our

appliances" it $loc%s the current from reaching our appliances $# $lo!ing off andprotecting our appliances in the process

In our electrical appliances" if e.cessive currents are not earthed" !e !ould e.perience

severe shoc% Earthing ta%es place in electrical appliances onl# !hen there is a pro$lem

and it is to save us from danger If in an electronic installation" a metallic part of an

electrical appliance comes in direct contact !ith a live !ire that results from ma#$e

failure of installation or other!ise" the metal !ill $e charged and static charge !ill

accumulate on it

If #ou happen to touch the metallic part at that moment #ou !ill $e &apped ut if themetallic part of the appliance is earthed" the charge !ill $e transferred to earth instead

of accumulating on the metallic part of the appliance Current don8t flo! through earth

!ires in electrical appliances" it does so onl# !hen there is pro$lem and onl# to direct

the un!anted current to earth in order to protect us from severe shoc%

In addition" if a live !ire touches accidentall# (in a fault# s#stem) to the metallic part of a

machine =o!" if a man touches that metallic part of the machine" then the current !ill

flo! through their $od# to the ground" hence" he !ill get shoc%ed (electrocuted) !hich

ma# lead to serious inuries even to death That8s !h# earthing is so important?

Electrical Grounding & Earthing.. To be continued

Please su$scri$e $elo!" if #ou !ant to get the upcoming post

a$out EarthingGroundingsuch as-

Calculate the si&e of Earth Continuit# Conductor" Earthing 'ead O Earth Electrodes for

differnt electrical devices and eHuipment such motors" transformers" home !iring etc $#

6imple calculations

Earthing Circuit and Earth ault Current

Protection of Earthing 6#stem and Additional devices used in the Earthing , Grounding

6#stem

Points To remem$er !hile Providing Grounding , Earthing

Important Instruction for Proper earthing s#stem


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Electricit# rules a$out Earthing

Mo! to Test Earth 5esistance $# Earth Tester

Mo! to test Earth loop 5esistance $# Am2Jeter O 4oltmeter

Protective Jultiple Earthing

And much more>

Earthing and Electrical Grounding Installation

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