Electrical Safety

Electrical Safety/ Lock out Tag out

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Should we be concerned? -Statistics Death/1 Lac Employees Electricians Structrual Metal Workers Laborers Electrical Power Installer Roofers Painters Supervisior Plumbers & pipe fitters. Carpenter Concrete finishers Brickmasons & Stonemason Tile Setters Drywall Installer Carpet Installer

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Fatalities Among U.S.Construction worker Survey

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Electrical Hazards Accidents do not just happen, they are caused. Most electrical accidents result from one of the following three factors or any combinations • Unsafe equipment or installation, • Unsafe environment, or • Unsafe work practices.

The following are specific electrical hazards the worker is exposed to in the work place.

Hazards of Electricity

Shock Arc Blast 3

Hazard Classification PRIMARY

SECONDARY

ELECTRIC SHOCK

FALLING FROM HEIGHT

ELECTRIC FIRE AND EXPLOSION

DROPPING OF TOOLS AND OBJECTS

ELECTRIC FLASH

RELEASE OF TOXIC GAS AND UV RAY

ELECTRIC BURNS

Avoid Unsafe Practices 4

High Voltage Precautions

Should we be concerned? -Human susceptibility BODY AREA

RESISTANCE IN OHMS

DRY SKIN OHMS

1,00,000 TO 6,00,000

WET SKIN

1000 OHMS

INTERNAL BODY

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HAND TO FOOT

400 TO 600 OHMS

EAR TO EAR

(ABOUT) 100 OHMS

Severity of Electrical Shock • The severity of shock depends on the personal sensitivity and varies from person to person. • It also depends on age, sex, heart condition etc. • Even for the same person, electrical shock depends on many factors. The severity of electrical shock is the function of the current (mA) and the time for which it flows through the body. 50 mA current can flow for 200 ms through the body without much danger, whereas 500 mA current even for 50 ms could be fatal. • It depends on rate of flow of current, path of current through the body and duration of time the body is in the circuit.

Reasons for Electric Shock 1. 2. 3. 4. 5.

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Victim touches bare live conductor. Victim touches poorly insulated conductor. OC / SC due to equipment failure. Static electricity. Lightning.

Effect on BODY Nervous system effects  One can stop breathing at 30 mA alternating current at 50Hz  Heart fibrillation can occur at 75 to 100 mA at 50 Hz.  Fibrillation means the heart is twitching and there is no blood flow to the body.  The heart can be damaged because it is in the path of most common pathways:  Hand to hand  Hand to foot

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Current Effect Injury depends on amplitude & time. When 50 Hz current passes through human body, from left hand to both legs & to the earth, for one second, it has different effects at different values, as tabulated below; Current (mA)

Effect

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Up to 1

No sensation

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1 to 8

Sensation there, but not painful

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8 to 15

Painful shock, but muscular control still there.

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15 to 20

Muscular control lost, resulting in sticking

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20 to 50

Severe muscular contraction

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50 to 200

Ventricular fibrillation and possible death

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> 200

Severe burns, severe ventricular fibrillation resulting in death.

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Fatal – Due to contact with open electric circuit Brief Description: The deceased was engaged in repairing of grinding machine. After checking of grinding machine he changed the carbon brushes, he plugged in the machine to nearby distribution panel near the repair platform where he was sitting. After plugging, he switched ON the supply and at the same time, grinding machine slipped from his hands. While trying to hold the machine, his hands touched the open electric circuit and he got electrocuted.

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ELECTRICAL SHOCK INCIDENT IN PLANT Two persons were engaged in preheating process, Heating coils of two different pipe joints were connected from one transformer e.g heater-1 & heater-2. Before going for lunch, deceased instructed to his helper to switch off the power of heater number-2 but mistakenly, he switched off the power of heater number-1 & went for the lunch. Heater number-2 needer to be shifted to another place for heat treatment of other pipes. After lunch, the deceased himself removed the live wire from heater number-2 & tried to connect it on the other pipe. While doing so live wire touched to his body & got electrocuted. Due to elctric shock, his body thrown away & disconnected from the live supply. At the same time, workers working nearby saw him, immediately called their vehicle & shifted him hospital where he succumbed to his injury. 11

LTI – Due to contact with HV Supply

Brief Description: 6.6 KV breaker panel inspection job was taken, after removal of the breaker, one of the engineer was checking the chattering sound inside the breaker chamber, his left hand accidently came in contact with the live part causing severe electric shock. 12

FATAL - Main Fan House, Waste gas fan Excitation Transformer. Brief description: Electrician of M/s. Prince Engg. and Electrician of M/s. Thompet received electrical shock and burn injuries while working in Bus bar of main fan excitation Transformer.

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Immediate cause:  Direct Contact with Bus Bar of Excitation Transformer which was not properly isolated.  Inattention / Lack of Awareness of Hazards. Root cause:  Proper Work Permit procedure not followed (Job was executed beyond the scope of the Work Permit). 14

Prevention methods Proper Isolation • Earthing & Grounding • Insulation • Protective devices - ELCB, RCCB • Guarding • Safe work practices. (SOP, PTW, PPE, etc.) •

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OUR STRATEGY…. • • • • • •

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Safety should be build at design stage Pre-startup safety Clear HIRAC and SOP Pro active inspection PTW Maintenance as per OEM recommendation

SAFETY PRACTICES In all electrical work, it is very necessary that certain elementary safety practices are observed. It has been found that quite a large number of accidents occur due to the neglect of these practices. Exercise Care

 Place yourself in a safe and secure position to avoid slipping, stumbling or moving backward against live conductors or apparatus.  Do not rely for protection upon the care assumed to be exercised by others.  Make a habit of being cautious.  Be on the lookout for danger notice plates, danger flags, warning boards and signals, etc.  Warn others when they seem to be in danger near live conductors or apparatus. PERSONAL APPAREL

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 While working on live conductors, do not roll up sleeves as dry cloth gives some protection against shocks.  Do not wear shoes with nailed soles. Shoes should have sewn soles, or preferably rubber soles.

SAFETY PRACTICES While welding wear goggles, safety glasses or any other eye protection as instructed by the person-in-charge depending upon the type of work handled. Do not wear suspenders and arm bands with metal buckles or other metal parts. These might come in close proximity to live parts and cause serious, if not fatal, injury. TREAT EVERYTHING AS LIVE

 Treat all electrical conductors and apparatus always as live and consequently dangerous to human life, unless it is positively known to be dead and properly earthed and take precautions accordingly. THINK BEFORE YOU ACT

 Think carefully before you act. Make sure you are right. Watch out for the other man and make sure he is right.  Never speak to any person working upon live mains or apparatus, unless the person doing the work is aware of your presence.

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SAFETY PRACTICES

DANGEROUS VOLTAGES

 All voltages are dangerous. It shall be borne in mind that even low voltage shock may be fatal.  Every person-in-charge of work on any mains or apparatus shall ensure himself that the same is free from dangerous leakage or induction and has been effectively earthed locally before permitting men to work upon it. DANGEROUS AREAS

 When working in areas which contain or may contain live mains and apparatus, fix danger notice plates, barriers, rails or other guarding arrangement for the working area.

CAUTION AREA IN FRONT OF THIS ELECTRICAL PANEL MUST BE KEPT CLEAR FOR 36 INCHES OSHA - NEC REGULATIONS

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SAFETY PRACTICES WARNING BOARDS

 Warning boards shall be placed by the person-in-charge on all switchgear before men are permitted to work and should only be removed by the person who has placed them. VISITORS AND UNAUTHORIZED PERSONS

 Visitors and unauthorized persons shall not be allowed to proceed in the vicinity of live mains and apparatus, unless accompained by an authorized person whose responsibility it shall be to ensure that his instructions regarding safety are strictly complied with. WORKING IN DAMP SITUATIONS

 Extra precautions should be taken when working in abnormally damp area.

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SAFETY PRACTICES PORTABLE ELECTRICAL APPARATUS

 All portable electrical apparatus shall be regularly examined, tested and maintained to ensure that the apparatus and leads are in good order.  Ensure that all portable appliances are provided with 3-pin plug and socket connections and that the metal work of the apparatus is effectively earthed.  All loose wiring, such as flexible cables for portable lamps, tools and trailing cables and other portable and transportable apparatus, shall be tested regularly at frequent intervals to ensure safety. Damaged/Broken case

Damaged Cord – outer sheath broken 21

Ground prong missing on three-prong plugs. Some tools are double insulated and won’t have a ground prong. That’s OK.

Guide Lines for Using There Portable are more chances of Devices Accidents taking place while working with Portable equipments. (single phase 230V AC, 110V/220V DC , three phase 415V AC). Use of portable electrical equipment or any temporary electrical installation, electrical supply shall be approved by the authorized electrical engineer. Each Portable Equipment should have an Identification Tag, Electrical Certification date and Next Certification due date pasted on it. In addition every time before use, the healthiness of the items like Cable, Gland, Earthing etc. shall be checked once again. All portable appliances shall have a preventive maintenance schedule and checklist. Duly tested ELCB of proper rating and sensitivity shall be used on the incoming side of supply so as to safeguard the operating personnel against electrical shock. No interlock or protection shall be bypassed or made ineffective. Preferably there shall not be any joint in the flexible PVC cable, where joint cannot be avoided due to large length (>100 meters) required joint shall be properly insulated. Only 3 pin plug of approved quality shall be used for tapping supply from the switch socket. 22

ELECTRICAL EQUIPMENT INSTALLATION Earthing :- Earthing means Equipment earthing and System earthing. •

Earthing system is designed to the maximum fault current based on equipment rating. Manufacturer provide two earthing points. The design of Earthing is considered to take care of future expansions. Earth strips are connected to “ Earth Pits “ For the system earthing, neutral point is connected to earth pit either directly or through a resistance.

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ELECTRICAL FIRE Electricity heat the media through which it passes. The electrical equipment heats up during use and more so in case of heater, bulbs, faulty equipment, loose connection. If the heat generated by the equipment is more than heat dissipated in the area leads to failure of the equipment/ insulation / fire. In 30 % of Industrial fires - the Electricity is involved in one way or other. Electrical fire = A defect + A medium that can 24

ELECTRICAL FIRE

Electrical Fires are due to …….  Damage due to rodents, termites and pests  Static Electricity  Improper protection against mechanical damage

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ELECTRICAL FIRE Motors :The principal hazards of Motors are as under •

Insulation failure due to age, inherent defect, Moisture, overload, inadequate ventilation or accumulation of dust.

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Sparking and arcing at commutators due to wear, dirt and faulty adjustments.

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Burning of armature coil or motor coils due to short circuit.

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Burning of cables due to insulation failure from persistent overload and short circuit.

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Over heating, arcing and sparking at terminals due to improper connections.

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Mechanical breakdown which may have indirect effect causing fires.

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ELECTRICAL FIRE Transformers :Transformer fails because of following reasons • Oil contaminated with moisture • Loose internal connections • Overheating of oil due to leaks • Overloading • Internal failure

Switch Gear Panels :Switchgear fire because of following reasons •

Loose internal connections

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Overloading

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Internal Mechanism failure

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Improper setting

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ELECTRICAL FIRE Electrical fires could be avoided by following precautions :Use good quality (ISI) wires/cables.

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Avoid joints in wiring - soldering and proper mechanical joints should be made if the same cannot be avoided.

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Old wiring should be renewed after ageing.

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Fuses used for protection should be of adequate capacity. The ratings should not be increased without ascertaining reason of fuse blowing.

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Fuse boards should be away from combustible materials like paper, oil, curtains etc.

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Avoid using stream of water, Wet blanket or stream of Soda-Acid Extinguisher on live mains or equipments.

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Before fighting fire ensure all Electrical mains, equipment, neighbouring mains switched - off.

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Treat all the cables, mains or equipments as live unless and until isolated positively.

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ELECTRICAL FIRE Control of Electrical Fires :-

Electrical fires are termed as Class-C / E fires Hand appliances : Use of Sand buckets  Co2 or DCP type extinguishers Fixed Installations : Automatic DCP type  Multityre system installation  Halon / Co2 flooding installation

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DISCHARGE ROD

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ZEBRA CROSSING TO BUS COUPLER/TIE FEEDER

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ISOLATION CONDITION MENTIONED ON FEEDER

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ISOLATION CONDITION MENTIONED ON FEEDER

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ISOLATION/EMERGENCY OPERATION CONDITION MENTIONED ON FEEDER

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SLD & DIRECTION OF FLOW OF CURRENT MENTIONED ON PANEL

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INCOMER & BUSCOUPLER LOCATION MARKED

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What To Do: Check For :• Pulse If person's heart has stopped, start CPR (Cardiopulmonary resuscitation), if you are trained. • Breathing If person isn't breathing, begin mouth-to-mouth resuscitation, if you are trained.

• Treat for shock Keep person lying down. If unconscious, put them on their side to let fluids drain. Don't move the person if neck or spine injuries are possible. Cover the person to maintain body heat

Stay with patient until help arrives Inform medical personnel about patient conditions 37

Summary :-

Appliances and equipment should have the proper label Don’t overload electrical circuits Make sure all electrical equipment is properly grounded Ensure power is off before working on electrical devices If you are not sure and something appears wrong, call an Electrical Engineer / electrician / Electrical Control Room Never bypass fuses and protective devices 38

Thank you

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LOTO PROVISION IN VCB

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