Sreerampuram, L-Kota Mandal, Vizianagaram-535161

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SAFETY GUIDELINES FOR ELECTRICAL

PROCEDURE:
Electrical work can be performed safely if the rules are followed, right precautions are taken and
one stays aware of the surroundings.

1. Electrical Room Related Safety Measures

i. The Electrical installations for Medium, High and Extra High voltage shall have a danger
notice both in English or Hindi and local language of the district with a sign of skulls and
bones.
ii. Minimum PPE requirement, hazards & precautions to be taken, Unauthorized Access
Prohibited signage, schematic layout of the Electrical Area with emergency equipment
location etc. are to be displayed at the entrance of Electrical Room.
iii. Electrical Shock Chart with instructions in English or Hindi and the local language of the
district and where Hindi is the local language, in English and Hindi for the restoration of
persons suffering from electric shock have to be affixed in a conspicuous place.
iv. Single Line Diagram to be displayed inside Electrical rooms.
v. The Emergency Action Plan with emergency contact numbers, employees’ name who are
trained on CPR & first aid to be displayed in electrical rooms.
vi. First aid boxes, stretchers, Oxypack, Gas Masketc to be made available in electrical
rooms or near vicinity.
vii. The Electrical installations for high and extra high voltage shall have a running tap of
drinking water and emergency safety shower with drinking water connection and proper
drainage facility. In case of electric burns, the burnt portion should be cooled down using
drinking water. In every manned high and extra high voltage sub section, an artificial
respirator to be provided.
viii. Good housekeeping to be maintained within the electrical room. The floor of Electrical
Substation should be kept free from slip/ trip/ fall hazard like open cable riser, moving
checker plate or floor board etc.
ix. Along with the main exit door, Emergency Exit door is to be provided and should be in
accessible safe condition in the 415 V and above electrical rooms.
x. Emergency lights fed from alternate source like UPS, DG, Batteries etc. are to be made
available near all the entrance, staircases and other strategic locations of electrical rooms
and those emergency lights are to be easily identifiable. Fluorescent signages to be
provided near the exits and strategic locations of Electrical Room.

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2. PPEs to be used for Electrical Job
PPEs to be used as per electrical job requirement at different voltage level are given below:

Voltage level PPEs to be used

Upto 650V Safety Shoes, Safety Helmet, Safety Goggles, 8.5 ~ 9 Calories /cm2
Electrical jobs ATPV LV Arc flash suit, 12 Calories /cm2 ATPV Hand gloves, 12
Calories /cm2 ATPV Arc Face Shield
Above 650 V Safety Shoes, Safety Helmet, Safety Goggles,
Electrical jobs 40 Calories/ cm2 ATPV HT Kool coat (FR pant and FR shirt and
Double layer switching coat, Hand gloves (Inner & Outer), Hard Hat
is included in the HT Kool Coat Kit)

3. Electrical Equipment Related Safety Measures

i. All the equipment used in the Electrical room shall be of sufficient current rating for its
normal duty as well as during the fault current. The equipment shall be of sufficient
mechanical strength to with stand the fault condition to ensure human safety.

ii. Every switch board of Medium, High or Extra High voltage shall comply the following
provisions:

A clear space of not less than 1 meter in width shall be provided in front of the switch board.
If there is any attachment at the back of the switchboard, the space shall be either less than 20
cm or more than 75 cm in width from the farthest outstanding part of the switchgear. If the
space behind the switchboard exceeds 75 cm in width, there shall be passage-way from either
end of the switchboard clear to height of 1.8 meters.

iii. All disconnect switches are to be identified and labelled stating the source of the circuit
and the equipment / circuit it is feeding.

iv. Electrical equipment, machinery and work areas to be kept clean. Access to panels and
junction boxes to be kept clear.

v. Insulation mat of proper grade to be used in front of electrical switchgears of 415 V &
above for the safety of operating personnel.

vi. All panel doors must be locked, made vermin proof by sealing entry holes specially from
cable entry points.

vii. Bus coupler panel and its cubicle shall be handled with utmost care. Red painting of Bus
coupler, Adaptor panel & Tie feeder panel from all sides (front, top and back) to be done for
easy identification and Adaptor panel to be treated as a part of Bus coupler.

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 viii. Incoming barrier of power supply and phase barrier inside the switchgear panel to
be ensured.

ix. There should not be any loose wirings, exposed joints, distribution box or junction box in
cover open condition in the workplace.

x. No High Voltage and Extra High Voltage system/ switchgear which has been kept
disconnected for period of six months or more for any maintenance job shall be energized
without Testing.

xi. All apparatus, cables and supply lines shall be maintained in healthy conditions and tests
shall be carried out periodically as per relevant code of practice of the Bureau of Indian
Standards.

xii. Records of all Tests, Repairs and Maintenance work of all the equipment in the Electrical
Room shall be duly kept in the history registers /SAP PM system so that these records can be
compared with earlier ones.

xiii. Over Current Protection to be provided to disconnect the supply automatically if the
rated current of the equipment, cable or supply line is exceeded for a time which the
equipment, cable or supply line is not designed to withstand.

xiv. Earth fault or Earth leakage protection to disconnect the supply automatically if the earth
fault current exceeds the limit of current for keeping the contact potential within the
reasonable value.

xv. Gas pressure type (Buchholz relay), winding and oil temperature protection with
provision of alarm and tripping shall be provided on all oil type transformers of rating 1,000
KVA and above.

xvi. Transformers of capacity 10 MVA and above shall be protected against incipient faults
by differential protection.

xvii. Where a sub-station or a switching station with apparatus having more than 2,000 litres
of oil is installed, whether indoors or outdoors, following precautions to be taken:

a) The baffle walls of four hours - fire rating shall be provided between the apparatus-

• where there is a single phase transformer banks in the switch-yards of generating stations
and sub-stations;

• on the consumer premises;

• where adequate clearance between the units is not available.

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 b) provision shall be made for suitable oil soak pit. Where use of more than 9,000 litres of
oil in any one oil tank, receptacle or chambers involved, provision shall be made for the
draining away or removal of any leaked/ escaped oil and special precautions shall be taken to
prevent the spread of any fire resulting from the ignition of the oil from any cause and
adequate provision shall' be made for extinguishing any fire which may occur.

c) Spare oil shall not be stored in the vicinity of any oil filled equipment in any such
substation or switching station.

d) All the transformers and switchgears shall be maintained in accordance with the
maintenance schedules prepared in accordance with the relevant codes of practice of Bureau
of Indian Standards.

e) The transformers of 10 MVA and above rating or in case of oil filled transformers with
oil capacity of more than 2,000 litres are to be provided with fire fighting system as per IS –
3034 or with Nitrogen Injection Fire Protection system.

xviii. Dry type of transformers only shall be used for installations inside the residential arid
commercial buildings.

xix. All the generators with rating of 100 KVA and above shall be protected against earth
fault leakage.

xx. All the generators of rating 1,000 KVA and above shall be protected against faults within
the generator winding using restricted earth faults within the generator winding using
restricted earth fault protection or differential protection or both.

xxi. Following safety interlocks are essential for the safe operation of the switchgears:

a) Isolators and controlling circuit breaker shall be interlocked so that isolators cannot be
operated unless the corresponding breaker is in open position.

b) Isolator and corresponding earthing switches shall be interlocked so that no earthing

switch can be closed until the corresponding isolator is in open condition.

c) Where two or more supplies are not intended to be operated in parallel, the respective
circuit breakers or linked switches controlling the supplies shall be interlocked (electrically
and mechanically to extent possible) to prevent possibility or any inadvertent paralleling or
back feed.

d) When two or more transformers are operated in parallel, the system shall be so arranged
as to trip the secondary breaker of transformer in case the primary breaker of that transformer
trips.

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 e) Where two or more generators are operated in parallel and neutral switching is adopted,
interlock shall be provided to ensure that generator breaker cannot be closed unless one of
the neutrals is connected to the earthing system.

4. Safety measures to be adopted by persons working on Electrical equipment

i. Only authorized /qualified personnel to be allowed to work on electrical job. Relevant

certification to be obtained from Electrical Inspectorate as applicable.

ii. No one should wear loose clothing, metal watch straps, bangles or finger rings while
working on electrical appliances.

iii. Any electrical appliance or machinery never to be used by user while in wet condition.

iv. The tools & tackles like screw drivers, pliers, cleaning brushes, Hand lamps, torches etc.
should be properly insulated.

v. Cords or tools with worn insulation or exposed wires should not be used.

vi. Only double-sided steps or stable ladders of FRP (dual support) to be used for
maintenance of panels and Bus-bar.

vii. Before any maintenance job is carried out on or near the live parts, the power source
should be proved dead. All voltage indicators should always be tested on a known “Live”
source immediately before and after use.

viii. No person should carry out work including maintenance, repairs, cleaning and testing
etc. on any parts of apparatus which are normally live unless such parts are proved to be dead
and Permit is taken in appropriate Work Permit form & Lock Out Tag Out done.

ix. Before touching any equipment, which has been energized and after taking precautions
regarding switching off supplies, the equipment shall be earthed.

a) Many makes of the switchgear have special arrangements fitted to the switchgear so that
bus-bars or feeders may be earthed through the circuit breaker. This is the safest method and
should always be used if the equipment is available.

b) If the above equipment is not available, earthing should be carried out using a covered
flexible earthing lead which has been first clamped to earth bar and then touched on the parts
to be earthed by a suitably insulating rod. The earthing lead shall have the cross-section area
commensurate with the short circuit rating of the switchgear.

x. During inspection or maintenance of mechanism of Circuit breaker, care should be taken

to avoid fingers being trapped in any part of the mechanism and avoid the possibility of

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 anyone being struck by moving parts of the mechanism or the moving contacts. It is
recommended to discharge the stored energy in the mechanism like release of the spring etc.

xi. Test should be made for the correct operation and calibration of protective devices
periodically and particularly after faults. It is essential that the settings should be restored to
the correct values after the test.

xii. In no circumstances should attempts be made to rewire a non re-wireable fuse.

xiii. Before charging of an electrical equipment after maintenance, its insulation resistance
shall be checked and IR values shall be ensured as per relevant Indian Standard.

5. Electrical Earthing Requirements

i. System Earthing: Neutral conductor of a 3-phase, 4-wire system and the middle conductor
of a 2-phase, 3-wire system, one point of single phase supply or artificial neutral point
created by having earthing transformer in 3- phase 3-wire system shall be earthed by not less
than two separate and distinct connections with a minimum of two different earth electrodes
or such large number as may be necessary to bring the earth resistance to a satisfactory value
both at the generating station and at the sub-station. The earth electrodes so provided, shall
be interconnected to reduce earth resistance.

ii. Equipment Earthing: The frame of every generator, stationary motor, portable motor, and
the metallic parts (not intended as conductors) of all transformers and any other apparatus
used for regulating or controlling energy and energy consuming apparatus shall be earthed by
two separate and distinct connections with earth.

iii. All earthing systems shall be tested for resistance with the help of an "Earth Tester" on a
dry day during the dry season, not less than once a year for high and extra high voltages
(>650 Volts) and not less than once every two years for low, medium voltages(<=650 Volts).
The combined value of resistance to earth should not exceed 1 Ohm for all voltages.

iv. The earth pit identification number, latest earth resistance, date of testing and due date of
testing shall be displayed on every earth pit name plate.

v. Earth pits to be properly maintained and chemical treatment of soil to be done as per
requirement to keep the earth resistance to a satisfactory value.

vi. Earth pits should be properly covered to avoid damage from man/ material/ vehicular
movement. Earth Pits to be properly barricaded as and where applicable.

vii. No material shall be allowed to be stacked/ dumped/ accumulate and debris shall not be
deposited near/ within the earthing station area.

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 viii. Protection against lightning shall be provided in accordance with specific guidelines
given in IS: 2309 (Code of practice for the protection buildings and allied structure against
Lightning).

6. General Safety Measures

i. Proper earthing and double earthing. General earthing for big power station, upto 0.5 ohm, big
substation 1 ohm, small substation 2 ohm and tower and other places up to 8 ohms. Due to
minimum earthing resistance, leakage current passes through it and not through a person. The
earthing should be inspected, tested and maintained properly. There should be a regular practice
to check earthing. Minimum voltage between ground and the earthwire should be 30 V.

ii. Use of approved insulated tools, rubber mats, shockproof gloves and boots, tester, fuse puller
or tong, D.O. rod, discharge rod, safety belt, hand lamp, wooden or insulated ladder and not
wearing metal ring, chain etc.

iii. Switches on the live line. Fused switches and air-current breaks should be used.

iv. Avoid temporary wiring. Avoid hurry and chance taking. Avoid left hand touching.

v. Employ qualified and trained electrician.

vi. Low voltage (24 V AC or 110V DC) in hazardous area.

vii. Good insulated and tested wiring.

viii. Isolation of machine/equipment before use.

ix. Work permit system as given in 18:5216-1969. Follow this IS for electrical work.

x. Safety tags and safety warning notices.

xi. Use of m a chine/ equipment within their limits i.e. no overloading.

xii Placement of oil type transformer outdoor.

xiii. Auxiliary room, battery room and control room to be separated.

xiv. Two exits in each electric room.

xv. Switch gear of the supply company should be separated from that of the consumer' by a
fireproof wall.

xvi. Precautions against thermal and mechanical stress, moisture, dust and overvoltage.
Automatic voltage regulators and overvoltage relays to protect from overvoltages.

xvii. Guard on transmission lines to prevent fault due to birds.

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xviii. Vermin proof enclosure for indoor switchgear. ?

xiv. Use of electric shock guard (ELCB) and 3-pin plug and socket to have proper earth
connection.

xx. Use of reactors or current limiting impendences or underground neutrals to reduce fault
levels.

xxi. Use protective relays, circuit breakers and rated fuses to control the current and to isolate the
faulty equipment speedily and automatically. Check before closing an OCB for high voltage
lines.

xxii. Use of grounding mat of low ohmic value and all non current- carrying parts to be
connected to the grounding grid by duplicate earth and segregated non current carrying metallic
parts to be electrically bonded.

xxiii. Record of ground resistance values and the physical condition of the grounding mat.

xxiv. Temperature sensitive alarm and protective relays to make alert and disconnect equipment
before overheating.

xxv. Interlocks to put into and out of service equipment correctly.

xxvi. Testing for high voltage, timing, polarity and insulation resistance.

xxvii. Cleaning and application of silicon grease to insulators to reduce pollution deposits.

xxviii. Safe cable trenches and preferably armoured cables.

xxiv. Transformers with oil safely, D.O. fuse, L.T. fuse, MCB, MCCB and automatic fire
protection system.

xxx. Generators and motors with fire proof doors automatically actuated by fire detectors.

xxxi. Ready CO, type and other fire extinguishers.

xxxii. Double communication systems with critical areas.

xxxiii. Clear approach available for fire fighting squad.

xxxiv. Flame and shock detectors and central fire annunciation system for fire safety.

xxxv. Diesel pump set for required fire water pressure.

xxxvi. Good housekeeping including well maintenance of all electrical installations.

xxxvii. Adequate working space and means of access around each apparatus.

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xxxviii. First-aid boxes and respiratory equipment ready. Training for artificial respiration to
save life from shock.

xxxix. Prevent higher humidity and temperature near electric installations. Work with full
protection in raining.

xxxx Use of flameproof/explosion proof equipment in flammable/explosive areas.

xxxxi. Earthing and bonding of solvent carrying pipelines and equipment.

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