Electricity

is the best friend

and worst enemy
Gobind Ajwani
Marketing Manager
www.alfredkim.net
 Electrical Safety ----- Protect People & Property

Extreme care, therefore, is required in Design, Construction, Operation,

Maintenance and Utilization of Electrical Equipment and Installations with
maximum attention to Safety.

Safety considerations primarily concern the following :

Basic Equipment for generation, transmission and Utilization.
Non-electrical items of plant and Machinery located in the vicinity of
Electrical Equipment.
Operating Personnel.
General Public.
 INDIAN ELECTRICITY RULES-
Let us review the important rules to get proper insight into safety aspects

Rule 29 : Construction, installation, protection, operation and

maintenance of electric supply lines and apparatus.

All electric supply lines and apparatus shall be sufficient rating for power,
insulation and estimated fault current and of sufficient mechanical strength
for the duty which they may be required to perform under the environmental
conditions of installation and shall be constructed, installed, protected,
worked and maintained in such a manner as to ensure safety of human
beings, animals and property.
1. Save as otherwise provided in these rules, the relevant code of practice of
the Bureau of Indian Standards including National Electrical Code, if any,
may also be followed to carry out the purposes of this rule and in the event
of any inconsistency the provision of these rules shall prevail.
2. The material and apparatus used shall conform to the relevant specifications
of the Bureau o Indian Standards where such specifications have already
been laid down.
 Rule 30 : Service lines and apparatus on consumer’s premises.

The supplier shall ensure that all electric supply lines, wires, fittings and apparatus
belonging to him or under his control which are on consumer’s premises, are in a
safe condition and in all respects fit for supplying energy and the supplier shall
take due precautions to avoid danger arising on such premises from such supply
lines, wires, fittings and apparatus.

2. Service-lines placed by the supplier on the premises of a consumer which are

underground or which are accessible shall be so insulated and protectetd by
the supplier as to be secure under all ordinary conditions against electrical,
mechanical, chemical or other injury to the insulation.

3.The consumer shall, as far as circumstances permit, take precautions for the
safe custody of the equipment on his premises belonging to the supplier.

4. The consumer shall also ensure that the installation under his control is
maintained in a safe condition.
 Rule 31 : Cut-out on consumer’s premises :

1. The supplier shall provide a suitable cutout in each conductor of every service-
line other than an earthed or earthed neutral conductor or the earthed external
conductor of a concentric cable within a consumer’s premises, in an accessible
position. Such cut-out shall be contained within an adequately enclosed
fireproof receptacle.
Where move than one consumer is supplied through a
common service-line, each such consumer shall be provided with an independent
cut-out at the point of junction to the common service.

2. Every electric supply line other than the earth or earthed neutral conductor of
any system or the earthed external conductor of a concentric cable shall be
protected by its owner.
 Rule 32 : Identification of earthed and earthed neutral conductors
and positions of switches therein.

Where the conductors include an earthed conductor of a two-wire system or a

conductor which is to be connected thereto, the following conditions shall be
compiled with :
1. An indication of a permanent nature shall be provided by the owner of the
earthed neutral conductor, or the conductor which is to be connected thereto,
to enable such conductor to be distinguished from any live conductor. Such
indication shall be provided –
a. where the earthed or earthed neutral conductor is the property of the supplier,
at or near the point of commencement of supply;
b. where a conductor forming part of a consumer’s system is to be connected to
the supplier’s earthed or earthed neutral conductor, at the point where such
connection is to be made;
c. in all other cases, at a point corresponding to the point of commencement of
supply or at such other points as may be approved by an inspector or any
officer appointed to assist the inspector and authorized under sub-rule (2) of
rule 4A.
2. No cut-out, link or switch other than a linked switch arranged to operate
simultaneously on the earthed or earthed neutral conductor and live conductors shall
be inserted or remain inserted or remain inserted in any earthed or neutral earthed
neutral conductor of a two-wire system or any earthed or earthed neutral conductor
of a multi-wire system or in any conductor connected thereto with the following
exceptions :
A link for testing purposes, or
B. switch for use in controlling a generator or transformer.
 Rule 33 : Earthed terminal on consumer’s premises :

1. The supplier shall provide and maintain on the consumer’s premises for the
consumer’s use a suitable earthed terminal in an accessible position at or near
the point of commencement of supply as defined under rule 58.
Provided that in the case of medium, high or extra-high voltage installation the
consumer shall, in addition to the aforementioned earthing arrangements,
provide his own earthing system with an independent electrode.
Provided further that the supplier may not provide any earthed terminal in the
case of installations already connected to his system on or before the date to
be specified by the State Government in this behalf if he is satisfied

2. The consumer shall take all reasonable precautions to prevent mechanical

damage to the earthed terminal and its lead belonging to the supplier
3. The supplier may recover from consumer the cost of installation on the basis of
schedule of charges notified in advance and where such schedule of charges
is not notified, the procedure prescribed, in sub-rule (5) of rule 82 will apply.
 Rule 33 : Earthed terminal on consumer’s premises :

1. The supplier shall provide and maintain on the consumer’s premises for the
consumer’s use a suitable earthed terminal in an accessible position at or near
the point of commencement of supply as defined under rule 58.
Provided that in the case of medium, high or extra-high voltage installation the
consumer shall, in addition to the aforementioned earthing arrangements,
provide his own earthing system with an independent electrode.
Provided further that the supplier may not provide any earthed terminal in the
case of installations already connected to his system on or before the date to
be specified by the State Government in this behalf if he is satisfied

2. The consumer shall take all reasonable precautions to prevent mechanical

damage to the earthed terminal and its lead belonging to the supplier
3. The supplier may recover from consumer the cost of installation on the basis of
schedule of charges notified in advance and where such schedule of charges
is not notified, the procedure prescribed, in sub-rule (5) of rule 82 will apply.
 Rule 34 : Accessibility of bare conductors.

Where bare conductors are used in a building, the owner of such conductors
Shall.
a. ensure that they are inaccessible;
b. provide in readily accessible position switches for rendering them dead b.
whenever necessary; and
c. take such other safety measures as are considered necessary by the
inspector.
 Rule 35 : Danger Notices :
The owner of every medium, high and extra-high voltage installation shall affix
permanently in a conspicuous position a danger notice in Hindi or English
and the local language of the district, with a sign of skull and bones of a
design as per the relevant ISS No. 2551 on –
a. every motor, generator, transformer and other electrical plant and equipment
together with apparatus used for controlling or regulating the same;
b. all supports of high and extra-high voltage overhead lines which can be easily
climbed upon without the aid of ladder or special appliances;
Explanation :- Rails, tubular poles, wooden supports, reinforced cement
concrete poles without steps, I-sections and channels, shall be deemed as
supports which cannot be easily climbed upon for the purposes of this
clause.
c. Luminous tube sign requiring high voltage supply, X-ray and similar high-
frequency installations;
Provided that where it is not possible to affix such notices on any generator,
motor, transformer or other apparatus, they shall be affixed as near as
possible thereto; or the Word ‘Danger’ and the voltage of the apparatus
concerned shall be permanently painted on it.
Provided further that where the generator, motor, transformer or other
apparatus is within an enclosure one notice affixed to the said enclosure
shall be sufficient for the purposes of this rule.
 RULE 36 : Handling of electric supply lines and apparatus :

1. Before any conductor or apparatus is handled, adequate precautions shall be

taken by earthing or other suitable means, to discharge electrically such
conductor or apparatus, and any adjacent conductor or apparatus if there is
danger therefrom, and to prevent any conductor or apparatus from being
accidentally or inadvertently electrically charged when persons are working
thereon.
Every person who is working on an electric supply line or apparatus or both
shall be provided with tools and devices such as gloves, rubber shoes,
safety belts, ladders, earthing devices, helmets, line testers, hand lines and
the like for protecting him from mechanical and electrical injury. Such tools
and devices shall always be maintained in sound and efficient working
conditions.
2. No person shall work on any live electric supply line or apparatus and no
person shall assist such person on such work, unless he is authorized in that
behalf, and take sthe safety measures approved by the Inspector.
3. Every telecommunication on supports carrying a high or extra-high voltage
line shall, for the purpose of working thereon, be deemed to be a high
voltage line.
RULE 37 : Rules 37 to 41A :
These appertain to provisions in respect of supply to vehicles, cranes etc,
cables for portable or transportable apparatus, cables protected by
bituminous materials, street boxes and distinction of different and multiple
feed installations.
RULE 37 : Rules 43 to 46 :
These concern stipulations regarding protective equipment like fire buckets,
fire extinguishers, First-aid boxes, gas masks, Instructions for restoration of
persons suffering from electric shock, intimation of accidents, precautions to
be adopted by consumers, owner occupiers, electrical contractors, electrical
workmen and suppliers along with provisions for periodical inspection and
testing of installations.
RULE 61 : Connection with earth.
These rules lay down the requirements of connection with earth of systems
at low voltage in cases where the voltage exceeds 125 volts and of systems
at medium voltage.
RULE 61A : Earth leakage protective device
The supply of energy to every electrical installation other than low voltage
installation below 5 KW and those low voltage installations which do not
attract provisions of Section 30 of the Indian Electricity Act, 1910, shall be
controlled by an earth leakage protective device so as to disconnect the
supply instantly on the occurrence or earth fault or leakage of current.
Provided that the above shall not apply to overhead supply lines having
protective devices which are effectively bonded to the neutral of supply
transformers and conforming to Rule 91 of IE Rules,1956.
 Electrical Earthing is most neglected part of the electrical safety
for people and property
Let us discuss What is Earthing?
Application of Earthing
• Allow zero potential to supply system
• Provide zero connection for Neutral
• Protect human against lightning and earth fault condition
• Protect the premises against lightning and earth fault
condition
• Provide low resistance and safe path for lightning and fault
current
• All metallic enclosure and extraneous conductive parts are
at equipotential
• LV System Earth
• Equipment Earth
• Clean Earth for signaling and noise
• Create equipotential platform
 Glossary

• Reference to IS3043 – 1987 Reaffirmed 2006

• “Earth” means the Ground, reference zero potential
• Rely on the system earth to maintain the system voltage and
normal voltage supply
• Equipment earth connects all non-conductive parts to protect
human against electric shock
• Class I protection – use of barrier/insulation and connection of
protective conductor to equipment metallic enclosure in order to
protect against electric shock
• Class II protection – beside of the basic insulation, addition layer
of insulation apply to the enclosure. Therefore no extraneous
conductive part. The additional layer is independent to the basic
insulation so that under failure of basic insulation, it offers
additional protection
 Glossary

Reference to IS3043 – 1987 Reaffirmed 2006

• “Earth” means the Ground, reference zero potential
• Rely on the system earth to maintain the system voltage and
normal voltage supply
• Equipment earth connects all non-conductive parts to protect
human against electric shock
• Class I protection – use of barrier/insulation and connection of
protective conductor to equipment metallic enclosure in order to
protect against electric shock
• Class II protection – beside of the basic insulation, addition layer
of insulation apply to the enclosure. Therefore no extraneous
conductive part. The additional layer is independent to the basic
insulation so that under failure of basic insulation, it offers
additional protection
 Glossary

Reference to IS3043 – 1987 Reaffirmed 2006

• “Earth” means the Ground, reference zero potential
• Rely on the system earth to maintain the system voltage and
normal voltage supply
• Equipment earth connects all non-conductive parts to protect
human against electric shock
• Class I protection – use of barrier/insulation and connection of
protective conductor to equipment metallic enclosure in order to
protect against electric shock
• Class II protection – beside of the basic insulation, addition layer
of insulation apply to the enclosure. Therefore no extraneous
conductive part. The additional layer is independent to the basic
insulation so that under failure of basic insulation, it offers
additional protection
 Types of Earthing
• Supply System – Neutral Earth
• System Earth
• Electrical Safety Earth
• Lightning Earth
• Generator Earth
• Protection Earth (i.e. surge arrestor)
• Telecom / Computer Earth
• Shielding Earth
• Integrated Earthing System (Advocated)
• Electrostatic Earth (Clean Room / Hospital)
• Cathodic protection (prevent rusty)
 Functions of Earth
• Equipment Earth : Path for fault
current, lower touch voltage,
protection against electric shock
• Lighting Earth : Low resistance path to
diverse the current under lightning
attack
• Telecom Earth : Signal Earth, reduce
noise and interference, stabilize DC
supply voltage and prevent electric
shock
• Computer Earth : reduce interference,
maintain supply voltages
 Earthing System
• Two Alphabetic system description
• First Alphabet – arrangement at Supply side
– T represents system directly earthed, multi-earthed
– I represents live part and earth path are separated, single point
earthed through high impedance
• Second Alphabet – arrangement at Consumer side
– T represents extraneous parts directly earthed, the earth point
independent from Supply side
– N represents extraneous parts connected to the protective
conductor of supply
• TN systems have two category:
–S protective conductor and neutral conductor are two wires
– C protective conductor and neutral conductor are the same
conductor
 Earthing System
TN-S
‧protective conductor and neutral conductor are independent
• All exposed metallic part connected with protective
conductor PE
• System Characteristics:
– Low earth fault loop impedance
– High earth fault current
• Advantages: earth fault protection device operates faster;
allow multi point earth, better earthing continuity; minimize
the use of earth fault relay because of low earth fault loop
impedance
• Disadvantages: high earth fault level; under earth fault
condition, low power factor (high inductance of long cable)
Earthing System
 Earthing System
TN-C
‧protective conductor and neutral conductor are combined
into one
• All exposed conductive parts connected to PEN
• System Characteristics :
– Low earth fault loop impedance
– High earth fault current
– More than one earth fault loops
• Advantages : no earth wire required; allow of multi-point
earth, better earthing continuity; neutral never have float
voltage; impedance of earth fault loop could be predicted
• Disadvantages : If not multi-point earthed, and the neutral
earth broken, the exposed metallic part may have float
voltage; high earth fault level, intervenue the operation of
earth fault protective device, current operated type device is
not appropriated, voltage detected type could be employed
Earthing System
 Earthing System
TT
• Supply side has one point earthing only
• Exposed metal connected to consumer earth system
• System characteristics :
– High earth fault loop impedance
– Low earth fault current
– Utility company need not to provide earth for
consumer
• Advantages : Under earth fault condition, higher
power factor; save earth wires
• Disadvantages : high demand of E/F relays,
individual earth system need higher investment,
higher touch voltage; induce Potential gradient
Earthing System
 Earthing System
IT

• System not connected with the earth (high

impedance earth or isolated earth), all exposed
conductive part connect to earth
• Neutral is totally isolated
• Infinity earth fault loop impedance
• Deemed less chance of electric shock
• Many disadvantages: phase current equal to live
voltage (because of floating Neutral); no zero
reference, may cause arcing when earth fault occurs;
to small of earth fault level, current type earth fault
detector cannot work properly
 Earthing System
Modern Current Earthing System
• Code 12 stipulated that electric equipment used to install its own
earthing protection system (TT system) and Main Earth Terminal shall
connected with utility company earth point. For instance, star of
transformer or metallic earth from supply cable
Earthing System
t
 Earthing System

Earth Electrode
• Design concerns:
• Resistance/impedance to earth
• Heat capacity (during earth fault,max 40kA)
• The potential gradient around the electrode during faults
• Mechanical strength and ability in anti-corrosion
• Earth electrode shall be rod / pipe, tape, buried copper plate,
re-bar and superstructure
• More than one electrode could be connected, the electrode
could be a mixed system
• Long electrode generally effective than short one. However
electrode too long does not have significant effects; larger
size do not have great effects in earthing impedance
Earthing System
 Earthing System
Electric Shock Protection
• Every premises shall have basic consideration to its
electric equipment’s safety – Electric Shock Protection
• Means of electric shock – Direct contact or indirect
contact
• Direct contact means direct touch to the live parts
• Indirect Contact means human contact to non-conductive
metal, of which the extraneous part becomes live during
faults
• Electric Shock Protection shall meet the requirements in
Code 11B including equipotential zones and automatic
disconnection under fault
• IEC report 479-1(1984) had studied “The effects in inject
of current into human and concerns on the current
magnitude, duration and flowing path
Earthing System
 Earthing System
Supplementary Equipotential Bond
• Supplementary equipotential bond maintain an extent of
equipotential zone
• Code 11F refers, all touchable non-conductive parts and
connections shall be sound connected
• Size of individual supplementary bond shall reference to
Table11(1) in Code, min. size shall be 2.5mm2 yellow and
green earth wire
• Other requirements:
– Min. size of bonding connecting two appliances enclosures shall
not be less than the size any of the protective conductors
– Min. size of bonding connecting appliances and non-conductive
parts shall not be less than half size of protective conductor
– Min. size of bonding between two non-conductive parts shall not
be less than half size of protective conductor of appliance
 Earthing System

Protective Conductor
• 4 type of conductor : Circuit Protective Conductor CPC, Main
Equipotential Bond Conductor, Supplementary Bonding Conductor,
Earthing Conductor
• Protective conductor could be : individual conductor, metallic armour
or sheath of cable, part of live cable, rigid metallic
conduits/Trunking/Pipe duct, containment of metallic sheath
• Reference to Code 11C and diagram11(1)
• Size of individual protective conductor shall refer to Code Table11(1),
and Table11(2), or substitue K-value to calculate equivalent area
• With difference protective device, protective conductor area refer to
Table11(3) to Table11(7)
• Calculation of size of Equipotential conductor and supplementary
bonding conductor refer to Code 11E and 11F
• Size of earth conductor shall meet the requirements in Code 11H
 PREREQUISITES FOR SAFETY

To sum up, with regard to safety one has to adopt a safe system of work
that ensures :-
• Compliance with relevant legislation.
• All fixed and portable installations are safe and tested.
• All electrical appliances and cables are tested and maintained.
• Only safe equipment is used.
• This system applies to all places of work.
• There are no short cuts to safety
• Legislation and Code of practice place absolute duties on employers,
employees and the self-employed to comply with all matters regarding
electrical safety that are within their control.
 Conventional Earthing (PIT) Type
• Metal pipe in specific to a diameter ( GI/CI).
• Prone to swift corrosion due to straight contact with the soil.
• Decompose of metal components and grounding plate.
• Insufficient and inadequate Galvanization standard. Variation in Ohmic value,

which may impact and trim down equipments life hence gigantic recurring
maintenance costs and potential threat to the safety of human life.
• Conventional and traditional method of earthing necessitates frequent
maintenance and has a diminutive life, this may be required to transform in
every 3-4years.
• The most commonly used substances are Sodium Chloride (also known as
common salt), Calcium Chloride, Sodium Carbonate, Copper Sulphate, Soft

Coke and Charcoal get washed away over a period of time and salt is known
to be a corrosive electrolyte, this may decay the pipe and conductor used for
earthing hence may not present consistent ohmic value.
• Much cumbersome and protracted process to install and have a need of very
deep holes in the earth any where between 40-100 feet. Circulation of short
circuit current is comparatively fewer in terms of charge dissipation hence
produces soaring potential at the pit resulting in low fault current as measure
up to preferred tripping circuit of fault protection relays.
 Compound Earthing - Electrode

IT employs highly secured strip in pipe in various sizes as per grounding

requirements instead solitary GI /CI pipe.
• Earthing Electrode does not at all get nearer in direct contact with the soil.
• Sealed maintenance free chemical filled Electrodes installed with high quality
particular & specific unsolvable chemical compounds prevent and protect
against any decompose.
• Compliant to IS: 3043 1987 code of practice for earthing . Electrode and
conductors are adequately galvanized (80-100 microns) and deliver steady &
consistent Ohmic value.
• Ultramodern techniques and compliant to earthing standard along with
reliable chemical filled maintenance free AlfredKim electrodes / GBFC
(grounding back fill compound) lasts longer with no recurring maintenance
and hassles.
• GBFC is a permanent & maintenance free (No recharging with salt or
chemical which may be corrosive) and maintain earth resistivity with time.
These compounds sets firmly and not dissolves or decompose or otherwise
pollute the soil.
 Compound Earthing - Electrode

Compact unit, make a hole in the ground by 6” to 8” in diameter to the desired

depth of the size of an Earthing Electrode (2/3 meters), trouble-free and
painless process to install, occupies lesser leg room and can be mounted in
less than an hour.
• Earthing Electrode is bound with exceedingly conductive soil to ensure the
dissipation of charge from the electrode is extremely high and the current
mass/ solidity across the electrode is exceptionally low resulting into soaring
fault current that is sufficient and adequate enough to trip the fault relays.
 USED OF GALVANISED - IRON

In the last three decades the transmission and distribution of electricity has
been taken over by extensive use of Alluminium conductors and cables. It is
a delibrate decision of Government of India To conserve the scarce
resources of copper.

It is the modern practice today to opt for chemical/compound electrode earthing

Which is more efficient and long lasting and easy to install.
 CONCLUSIONS AND RECOMMENDATIONS

The overall requirements to ensure safety are :

1. Any installation, use and maintenance of equipment must reflect specific
safety requirements with regard to adverse conditions i.e. weather
conditions, exposure to corrosive or flammable environments, operation in
adjusty atmosphere etc.
2. Recommended clearances and creepage distances in accordance with the
system voltage should be maintained.
3. Connections should always be suitable and adequate for the purpose for
which they are being used. The use of electrical tape alone for connections
is forbidden.
4. It must be ensured that any protection for electrical installations and
equipment e.g. fuses and earth leakage circuit breakers (ELCBs), are
suitably rated, sufficient and within safe working limits. In the case of ECLBs
the test trip button should be operated regularly to check its healthiness.
5. Protective devices for under voltage, over current, short circuit, earth fault etc.
should be incorporated in accordance with regulations and recommended
codes of practice.
 CONCLUSIONS AND RECOMMENDATIONS
6. Portable electrical tools should either be all insulated or of double insulation
construction where possible. Where portable equipment with earthed
metalwork is used, it is recommended that portable or fixed earth leakage
protection be used. This is particularly important in harsh environments.
7. All electrical installations and equipment must have adequate means to
enable them to be isolated from the electric supply in order to prevent
danger.
8. All isolator switches should be easily accessible and passageways to them
kept clear at all times.
9. All switches and fuse ways must be clearly labeled as to indicate the circuit or
function controlled and all switches and distribution covers must be kept
closed at all times unless being worked on by a competent authorized
person.
10. Whereever possible, suitable interlocks should be provided to ensure correct
switching sequence and fail-safe disconnection.
11. Adequate working space i.e. access and lighting must be provided to all
electrical equipment on which or near which work is being carried out which
may give rise to danger.
 CONCLUSIONS AND RECOMMENDATIONS

12. There should be adequate arrangements to ensure that electrical

equipment that has been made ‘dead’, whilst work is being carried out on or
near such equipment, cannot be electrically charged if this would then
present danger.

This can be physically achieved by ensuring that a ‘lock-out’ system is used,

i.e. the isolator controlling equipment is physically locked in the ‘off’ position.
Where a ‘lock-out’ system cannot be used then there should be a procedure
for ensuring that fuses are removed and held by the authorized person
carrying out the work.
Any work being undertaken on an electrical installation or equipment should be
subject to a safe system of work and the Permit-to-Work Procedure.
13. Where work on electrical equipment is being undertaken by ‘in-house’
competent persons then suitable protective equipment must be provided.
Examples of such equipment may be goggles, gloves, insulating mats,
insulated tools and test probes.
 CONCLUSIONS AND RECOMMENDATIONS

14. Notices giving details of emergency resuscitation procedures in the event of

electrick shock should be displayed at those locations where the risk of
electric shock is greater e.g. sub-stations and electrical test areas.
15. Only competent authorized persons, i.e. those with sufficient experience and
training, should be engaged in any work on an electrical installation or
equipment.