-
Earthing, Types of Electrical Earthing & Electrical
Grounding
http://www.electricaltechnology.org/2015/05/earthing-and-electrical-grounding-types-of-earthing.html[5/13/2015
10:04:43 AM]
Earthing and Electrical Grounding Installation | A Complete
Guide Electrical Technology 05/10/2015 Basic Electrical
Fundamentals, EE Instruments/Devices &Components, Electrical
Design, Electrical Wiring (Basic for Home), How To, Protection,
Questions/Answers (Electrical), Troubleshooting Leave a comment
3,258 Views
Table of Contents [Hide]
Earthing and Types of Electrical Earthing | Electrical Grounding
Installation (Step by Step)What is Grounding or Earthing?Need of
Earthing or Grounding. Why Earthing is Important?Different Terms
used in Electrical EarthingPOINTS TO BE EARTHEDComponents of
Earthing SystemSize of Earth Continuity ConductorEarthing Lead or
Earthing JointSize of the Earthing LeadEarthing Electrode or Earth
PlateEarth Plate or Earth Electrode Size for Small
installationMethods of Earthing | Types of Earthing
1). Plate Earthing:2). Pipe Earthing:3). Rod Earthing4).
Earthing through the Waterman5). Strip or Wire Earthing:
General method of Earthing / Proper Grounding Installation (Step
by Step)SI specification for EarthingDangers Of Not Earthing A
Supply SystemElectrical Grounding & Earthing.. To be
continued
-
Earthing, Types of Electrical Earthing & Electrical
Grounding
http://www.electricaltechnology.org/2015/05/earthing-and-electrical-grounding-types-of-earthing.html[5/13/2015
10:04:43 AM]
Earthing and Types of Electrical Earthing | Electrical Grounding
Installation (Step by Step)
Earthing, Grounding, Methods Of Earthing, Types of Earthing And
Is Specifications In Respect To Earthing Of Electrical
Installations
Keep In mind:
We have to updated this post with different and useful articles
related to Earthing & Grounding.
Please Subscribe to Electrical Technology Blog by Email and dont
miss even a single post about the story. OR just see the last
paragraph of the article. Thanks
Happy learning
What is Grounding or Earthing?To connect the metallic
(conductive) Parts of an Electric appliance or installations to the
earth (ground) is called Earthing or Grounding.
In other words, to connect the metallic parts of electric
machinery and devices to the earth plate or earth electrode (which
is buried in the moisture earth) through a thick conductor wire
(which has very low resistance) for safety purpose is known as
Earthing or grounding.
To earth or earthing rather, means to connect the part of
electrical apparatus such as metallic covering of metals, earth
terminal of socket cables, stay wires that do not carry current to
the earth. Earthing can be said as the connection of the neutral
point of a power supply system to the earth so as to avoid or
minimize danger during discharge of electrical energy.
-
Earthing, Types of Electrical Earthing & Electrical
Grounding
http://www.electricaltechnology.org/2015/05/earthing-and-electrical-grounding-types-of-earthing.html[5/13/2015
10:04:43 AM]
Good to knowDifference between Earthing, Grounding and
Bonding.Let me clear the confusion among earhing, grounding and
bonding.
Earthing and Grounding is the same terms used for earthing.
Grounding is the commonly word used for earthing in the North
American standards like IEEE, NEC, ANSI and UL etc while, Earthing
is used in European, Common wealth countries and Britain standards
like IS and IEC etc.
The word Bonding used for jointing two wires (as well as
conductors, pipes or appliances together. Bonding is known as
connecting the metallic parts of different machines which is not
considered to be carrying electric current during normal operation
of the machines to bring them at the same level of electric
potential.
Need of Earthing or Grounding. Why Earthing is Important?The
primary purpose of earthing is to avoid or minimize the danger of
electrocution, fire due to earth leakage of current through
undesired path and to ensure that the potential of a current
carrying conductor does not rise with respect to the earth than its
designed insulation.
-
Earthing, Types of Electrical Earthing & Electrical
Grounding
http://www.electricaltechnology.org/2015/05/earthing-and-electrical-grounding-types-of-earthing.html[5/13/2015
10:04:43 AM]
When the metallic part of electrical appliances (parts that can
conduct or allow passage of electric current) comes in contact with
a live wire, maybe due to failure of installations or failure in
cable insulation, the metal become charged and static charge
accumulates on it. If a person touches such a charged metal, the
result is a severe shock.
To avoid such instances, the power supply systems and parts of
appliances have to be earthed so as to transfer the charge directly
to the earth.
Below are the basic needs of Earthing.
To protect human lives as well as provide safety to electrical
devices and appliances from leakage current.
To keep voltage as constant in the healthy phase (If fault
occurs on any one phase).
To Protect Electric system and buildings form lighting.
To serve as a return conductor in electric traction system and
communication.
To avoid the risk of fire in electrical installation
systems.
Different Terms used in Electrical EarthingEarth: The proper
connection between electrical installation systems via conductor to
the buried plate in the earth is known as Earth.
Earthed: When an electrical device, appliance or wiring system
connected to the earth through earth electrode, it is known as
earthed device or simple Earthed.
Solidly Earthed: When an electric device, appliance or
electrical installation is connected to the earth electrode without
a fuse, circuit breaker or resistance/Impedance, It is called
solidly earthed.
Earth Electrode: When a conductor (or conductive plate) buried
in the earth for electrical earthing system. It is known to be
Earth Electrode. Earth electrodes are in different shapes like,
conductive plate, conductive rod, metal water pipe or any other
conductor with low resistance.
Earthing Lead: The conductor wire or conductive strip connected
between Earth electrode and Electrical installation system and
devices in called Earthing lead.
Earth Continuity Conductor: The conductor wire, which is
connected among different electrical devices and appliances like,
distribution board, different plugs and appliances etc. in other
words, the wire between earthing lead and electrical device or
appliance is called earth continuity conductor. It may be in the
shape of metal pipe (fully or partial), or cable metallic sheath or
flexible wire.
Sub Main Earthing Conductor: A wire connected between switch
board and distribution board i.e. that conductor is related to sub
main circuits.
Earth Resistance: This is the total resistance between earth
electrode and earth in (Ohms). Earth resistance is the algebraic
sum of the resistances of earth continuity conductor, earthing
lead, earth electrode and earth.
POINTS TO BE EARTHED
-
Earthing, Types of Electrical Earthing & Electrical
Grounding
http://www.electricaltechnology.org/2015/05/earthing-and-electrical-grounding-types-of-earthing.html[5/13/2015
10:04:43 AM]
Earthing is not done anyhow. According to IE rules and IEE
(Institute of Electrical Engineers) regulations,
Earth pin of 3-pin lighting plug sockets and 4-pin power plug
should be efficiently and permanently earthed.
All metal casing or metallic coverings containing or protecting
any electric supply line or apparatus such as GI pipes and conduits
enclosing VIR or PVC cables, iron clad switches, iron clad
distribution fuse boards etc should be earthed (connected to
earth).
The frame of every generator, stationary motors and metallic
parts of all transformers used for controlling energy should be
earthed by two separate and yet distinct connections with the
earth.
In a dc 3-wire system, the middle conductors should be earthed
at the generating station.
Stay wires that are for overhead lines should be connected to
earth by connecting at least one strand to the earth wires.
Components of Earthing SystemA complete electrical earthing
system consists on the following basic components.
Earth Continuity ConductorEarthing LeadEarth Electrode
-
Earthing, Types of Electrical Earthing & Electrical
Grounding
http://www.electricaltechnology.org/2015/05/earthing-and-electrical-grounding-types-of-earthing.html[5/13/2015
10:04:43 AM]
Components of Electrical Earthing System Earth Continuity
Conductor or Earth Wire
That part of the earthing system which interconnects the overall
metallic parts of electrical installation e.g. conduit, ducts,
boxes, metallic shells of the switches, distribution boards,
Switches, fuses, Regulating and controlling devices, metallic parts
of electrical machines such as, motors, generators, transformers
and the metallic framework where electrical devices and components
are installed is known as earth wire or earth continuity conductor
as shown in the above fig.
The resistance of the earth continuity conductor is very low.
According to IEEE rules, resistance between consumer earth terminal
and earth Continuity conductor (at the end) should not be increased
than 1. In simple words, resistance of earth wire should be less
than 1.
Size of the Earth Continuity Conductor or Earth Wire depends on
the cable size used in the wiring circuit.
Size of Earth Continuity ConductorThe cross sectional area of
the Earth Continuity Conductor should not be less than the half of
the
-
Earthing, Types of Electrical Earthing & Electrical
Grounding
http://www.electricaltechnology.org/2015/05/earthing-and-electrical-grounding-types-of-earthing.html[5/13/2015
10:04:43 AM]
cross sectional area of the thickest wire used in the electrical
wiring installation.
Generally, the size of the bare copper wire used as earth
continuity conductor is 3SWG. But keep in mind that, dont use less
than 14SWG as earth wire. Copper strip is also can be used as earth
continuity conductor instead of bare copper wire but dont go for it
until manufacture recommend it.
Earthing Lead or Earthing JointThe conductor wire connected
between earth continuity conductor and earth electrode or earth
plate is called earthing joint or Earthing lead. The point where
earth continuity conductor and earth electrode meet is known as
connecting point as shown in the above fig.
Earthing lead is the final part of the earthing system which is
connected to the earth electrode (which is underground) through
earth connecting point.
There should be minimum joints in earthing lead as well as lower
in size and straight in the direction.
Generally, copper wire can be used as earthing lead but, copper
strip is also used for high installation and it can handle the high
fault current because of wider area than the copper wire.
A hard drawn bare copper wire 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.
To increase the safety factor of installation, two copper wires
are used as earthing lead to connect the device metallic body to
the earth electrode or earth plate. I.e. if we use two earth
electrodes or earth plats, there would be four earthing leads. It
should not be considered that the two earth leads are used as
parallel paths to flow the fault currents but both paths should
work properly to carry the fault current because it is important
for better safety.
-
Earthing, Types of Electrical Earthing & Electrical
Grounding
http://www.electricaltechnology.org/2015/05/earthing-and-electrical-grounding-types-of-earthing.html[5/13/2015
10:04:43 AM]
Size of the Earthing LeadThe size or area of earthing lead
should not be less than the half of the thickest wire used in the
installation.
The largest size for earthing lead is 3SWG and the minimum size
should not be less than 8SWG. If 37/.083 wire is used or the load
current is 200A from the supply voltage, then it is recommended to
use copper strip instead of double earthing lead. The earth lead
connection methods is shown in the above fig.
Note: We will post additional article about Earth Plate size
with simple calculations Stay tune.
Earthing Electrode or Earth PlateA metallic electrode or plate
which is buried in the earth (underground) and it is the last part
of the electrical earthing system. In simple words, the final
underground metallic (plate) part of the earthing system which is
connected with earthing lead is called earth plate or earth
electrode.
-
Earthing, Types of Electrical Earthing & Electrical
Grounding
http://www.electricaltechnology.org/2015/05/earthing-and-electrical-grounding-types-of-earthing.html[5/13/2015
10:04:43 AM]
A metallic plate, pipe or rode can be used as an earth electrode
which has very low resistance and carry the fault current safely
towards ground (earth).
Size of Earthing Electrode
Both copper and iron can be used as earthing electrode.
The size of earth electrode (In case of copper)
22 (two foot wide as well as in length) and 1/8 inch thickness..
I.e. 2 x 2 x 1/8. (600x600x300 mm)
In case of Iron
2 x2 x = 600x600x6 mm
It is recommended to bury the earth electrode in the moisture
earth. If it is not possible, then put water in the GI (Galvanized
Iron) pipe to make possible the moisture condition.
In the earthing system, put the earth electrode in vertical
position (underground) as shown in the above fig. Also, put a 1
foot (about 30cm) layer of powdered charcoal and lime mixture
around the earth plate (dont confuse with earth electrode and earth
plate as both are the same thing).
This action makes the possible increase in the size of the earth
electrode which leads a better continuity in the earth (earthing
system) and also helps to maintain the moisture condition around
earth plate.
P.S: We will post Example calculation about Earth Electrode
Sizing Stay tune.
Good to know:
-
Earthing, Types of Electrical Earthing & Electrical
Grounding
http://www.electricaltechnology.org/2015/05/earthing-and-electrical-grounding-types-of-earthing.html[5/13/2015
10:04:43 AM]
Dont use coke (after burning coal in the furnace to emit all the
gases and other components, the remaining 88% carbon is called
coke) or stone coal instead of charcoal (wood coal) because it
causes to corrosion in the earth plate.
Since, the water level is different in the different areas;
therefore, the depth for earth electrode installation is also
different in various areas. But, the depth for earth electrode
installation should not be less than 10ft (3 meter) and should
below 1 foot (304.8mm) from the constant water level.
Motors, Generator, Transformers etc should be connected from to
earth electrode two different places.
Earth Plate or Earth Electrode Size for Small installationIn
small installation, use metallic rod (diameter = 25mm (1inch) and
length = 2m (6ft) instead of earth plate for earthing system. The
metallic pipe should be 2 meter below from the surface of ground.
To maintain the moister condition, put 25mm (1inch) coal and lime
mixture around the earth plate.
For effectiveness and convenience, you may use the copper rods
12.5mm (0.5 inch) to 25mm (1 inch) diameter and 4m (12ft) length.
We will discuss the installation method of rod earthing latter.
Methods of Earthing | Types of EarthingEarthing can be done in
many ways. The various methods employed in earthing (in house
wiring or factory and other connected electrical equipment and
machines) are discussed as follows:
1). Plate Earthing:In plate earthing system, a plate made up of
either copper with dimensions 60cm x 60cm x 3.18mm (i.e. 2ft x 2ft
x 1/8 in) or galvanized iron (GI) of dimensions 60cm x 60cm x 6.35
mm (2ft x 2ft x in) is buried vertical in the earth (earth pit)
which should not be less than 3m (10ft) from the ground level.
For proper earthing system, follow the above mentioned steps in
the (Earth Plate introduction) to maintain the moisture condition
around the earth electrode or earth plate.
-
Earthing, Types of Electrical Earthing & Electrical
Grounding
http://www.electricaltechnology.org/2015/05/earthing-and-electrical-grounding-types-of-earthing.html[5/13/2015
10:04:43 AM]
2). Pipe Earthing:A galvanized steel and a perforated pipe of
approved length and diameter is placed vertically in a wet soil in
this kind of system of earthing. It is the most common system of
earthing.
The size of pipe to use depends on the magnitude of current and
the type of soil. The dimension of the pipe is usually 40mm (1.5in)
in diameter and 2.75m (9ft) in length for ordinary soil or greater
for dry and rocky soil. The moisture of the soil will determine the
length of the pipe to be buried but usually it should be 4.75m
(15.5ft).
-
Earthing, Types of Electrical Earthing & Electrical
Grounding
http://www.electricaltechnology.org/2015/05/earthing-and-electrical-grounding-types-of-earthing.html[5/13/2015
10:04:43 AM]
3). Rod Earthing it is the same method as pipe earthing. A
copper rod of 12.5mm (1/2 inch) diameter or 16mm (0.6in) diameter
of galvanized steel or hollow section 25mm (1inch) of GI pipe of
length above 2.5m (8.2 ft) are buried upright in the earth manually
or with the help of a pneumatic hammer. The length of
-
Earthing, Types of Electrical Earthing & Electrical
Grounding
http://www.electricaltechnology.org/2015/05/earthing-and-electrical-grounding-types-of-earthing.html[5/13/2015
10:04:43 AM]
embedded electrodes in the soil reduces earth resistance to a
desired value.
Copper Rod Electrode Earthing System
4). Earthing through the WatermanIn this method of earthing, the
waterman (Galvanized GI) pipes are used for earthing purpose. Make
sure to check the resistance of GI pipes and use earthing clamps to
minimize the resistance for proper earthing connection.
If stranded conductor is used as earth wire, then clean the end
of the strands of the wire and make sure it is in the straight and
parallel position which is possible then to connect tightly to the
waterman pipe.
5). Strip or Wire Earthing:In this method of earthing, strip
electrodes of cross-section not less than 25mm x 1.6mm (1in x
0.06in) is buried in a horizontal trenches of a minimum depth of
0.5m. If copper with a cross-section
of 25mm x 4mm (1in x 0.15in) is used and a dimension of 3.0mm2
if its a galvanized iron or steel.
If at all round conductors are used, their cross-section area
should not be too small, say less than
6.0mm2 if its a galvanized iron or steel. The length of the
conductor buried in the ground would give a sufficient earth
resistance and this length should not be less than 15m.
General method of Earthing / Proper Grounding Installation (Step
by Step)
-
Earthing, Types of Electrical Earthing & Electrical
Grounding
http://www.electricaltechnology.org/2015/05/earthing-and-electrical-grounding-types-of-earthing.html[5/13/2015
10:04:43 AM]
The usual method of earthing of electric equipments, devices and
appliances are as follow:
1. First of all, dig a 5x5ft (1.51.5m) pit about 20-30ft (6-9
meters) in the ground. (Note that, depth and width depends on the
nature and structure of the ground)
2. Bury an appropriate (usually 2 x 2 x 1/8 (600x600x300 mm)
copper plate in that pit in vertical position.
3. Tight earth lead through nut bolts from two different places
on earth plate.
4. Use two earth leads with each earth plate (in case of two
earth plates) and tight them.
5. To protect the joints from corrosion, put grease around
it.
6. Collect all the wires in a metallic pipe from the earth
electrode(s). Make sure the pipe is 1ft (30cm) above the surface of
the ground.
7. To maintain the moisture condition around the earth plate,
put a 1ft (30cm) layer of powdered charcoal (powdered wood coal)
and lime mixture around the earth plate of around the earth
plate.
8. Use thimble and nut bolts to connect tightly wires to the bed
plates of machines. Each machine should be earthed from two
different places. The minimum distance between two earth electrodes
should be 10 ft (3m).
9. Earth continuity conductor which is connected to the body and
metallic parts of all installation should be tightly connected to
earth lead.
10. At last (but not least), test the overall earthing system
through earth tester. If everything is going about the planning,
then fill the pit with soil. The maximum allowable resistance for
earthing is 1. If it is more than 1 ohm, then increase the size
(not length) of earth lead and earth continuity conductors. Keep
the external ends of the pipes open and put the water time to time
to maintain the moisture condition around the earth electrode which
is important for the better earthing system.
SI specification for EarthingVarious specifications in respect
to earthing as recommended by Indian Standards are given below.
Here are few;
An earthing electrode should not be situated (installed) close
to the building whose installation system is being earthed at least
more than 1.5m away.
The earth resistance should be low enough to cause the flow of
current sufficient to operate the protective relays or blow fuses.
Its value is not constant as it varies with weather because it
depends on moisture (but should not be less than 1 Ohm).
The earth wire and earth electrode will be the same
material.
The earthing electrode should always be placed in a vertical
position inside the earth or pit so that it may be in contact with
all the different earth layers.
Dangers Of Not Earthing A Supply SystemThe danger of not
earthing a supply system is that during discharge of electric
current, the impedance of the path of the current is low, a large
amount of current flows to earth. When the current exceeds the
limiting value, the fuse provided in the circuit will blow off and
will cut off the appliances from power supply and there is also a
risk of fire in the system.
-
Earthing, Types of Electrical Earthing & Electrical
Grounding
http://www.electricaltechnology.org/2015/05/earthing-and-electrical-grounding-types-of-earthing.html[5/13/2015
10:04:43 AM]
In addition, if a live wire touches accidentally (in a faulty
system) to the metallic part of a machine. Now, if a man touches
that metallic part of the machine, then the current will flow
through their body to the ground, hence, he will get shocked
(electrocuted) which may lead to serious injuries even to death.
Thats why earthing is so important?
Electrical Grounding & Earthing.. To be continuedPlease
subscribe below, if you want to get the upcoming post about
Earthing/Grounding such as:
Calculate the size of Earth Continuity Conductor, Earthing Lead
& Earth Electrodes for differnt electrical devices and
equipment such motors, transformers, home wiring etc by Simple
calculations
Earthing Circuit and Earth Fault Current
Protection of Earthing System and Additional devices used in the
Earthing / Grounding System
Points To remember while Providing Grounding / Earthing
Important Instruction for Proper earthing system
Electricity rules about Earthing
How to Test Earth Resistance by Earth Tester
How to test Earth loop Resistance by Am-Meter &
Voltmeter
Protective Multiple Earthing
And much more.
Enter your Email for Latest Updates like the above one!Enter
Your Email Address:
821.4k
Like
1875
2
85
1
66
Share
1
2318
-
Earthing, Types of Electrical Earthing & Electrical
Grounding
http://www.electricaltechnology.org/2015/05/earthing-and-electrical-grounding-types-of-earthing.html[5/13/2015
10:04:43 AM]
Facebook Twitter Google + Stumbleupon LinkedIn Pinterest
electricaltechnology.orgEarthing, Types of Electrical Earthing
& Electrical Grounding
lwZXMtb2YtZWFydGhpbmcuaHRtbAA=: form1: email: input8:
Fsc2Umc2hvd19mYWNlcz1mYWxzZQA=: form0: button0: