Electrical Safetyj 1365

8/3/2019 Electrical Safetyj 1365

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ELECTRICAL SAFETY

Electricity is the most commonly useditem in our daily use. When we are

making extensive use of electricity,aserious thought is also required to begiven to the dangers involved in its use.


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WHY ELECTRICAL SAFETY ?

15 to 20 accidents in factories, one turnout to be fatal (Safety analysis report)

More & more new areas are addedeveryday.

Probability of accident is more ascompared to other agency


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ELECTRICAL HAZARDS1. Electric shock

2. Electric burn3. Electric fires & Explosions

4. Other hazards


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WHAT IS ELECTRIC SHOCK ?

When a person comes in contact with :

Both wires of electric supply.

One wire of an energised circuit &

ground.Accidentally energised metallic part

while standing on ground.


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EFFECTS OF CURRENT FLOW IN HUMAN BODY

1 to 8 mA - not painful

8 to 15 mA -painful shock 15 to 20 mA -painful shock, muscular

control lost.

20 to 50 mA -breathing difficulties 50 to 100 mA -leads to death

200 mA & more -severe burns,clampdown of heart,leads to death.


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SEVERITY OF ELECTRIC SHOCK

1. Amount of current flow.

2. Path of current flow.3. Period of current flow

4. Nature of current

5. Frequency6. Resistance offered by body to flow of

current.


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CAUSES OF ELECTRIC SHOCK1. Insulation failure

2. Equipment failure

3. Poor maintenance

4. Wrong working method

5. Sub standard material6. Unauthorized personnel

7. Lack of training and knowledge


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WHAT IS ELECTRIC BURN ? When a person comes in contact with

live wire , due to heating effect ofelectricity, receives electric burn.

Electrical burns is another commonhazard associated with the use of

electricity.A flash over burn could be a serious

hazard dealing with very high voltages.


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TYPES OF ELECTRIC BURNS1. Contact burn

2. Flash / arc burn3. Scattering of vaporised metal

4. Arc eye & metal fume fever


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ELECTRIC FIRES &

EXPLOSIONS

Fires and explosions may also be

caused by electricity. The property of electric current to

heat the conductors and looseconnections causing sparks and arcslead to fires & explosions.


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CAUSES OF ELECTRIC FIRES &

EXPLOSIONS

1. Overloading2. Incorrect fuses /protective devices

3. Poor maintenance

4. Explosive atmosphere5. Static electricity


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OTHER HAZARDSSome other hazards of electricity:

Loose balance after violent jerk of

electric shock. Fallen from overhead heights.

Hit or strike against tools fallen from

height cause injury. Presence of flammable vapours area

cause fire & explosion.Contd


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Metallic segments thrown or ejected out ofbursting of ACB may cause injury to near by

person. Deafening sound produced by the blowing of

HT fuses or explosion may rapture the eardrum.

Insulating oil fumes and vapours may causeadverse effect on health.


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PROTECTION FROM ELECTRICAL INJURIES

AND PREVENTION OF ELECTRICAL ACCIDENTS

Earthing

Low voltage supply

Isolating transformers

Double insulated tools

Protection against leakage currents Overload protection

Contd


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Flame-proof equipments

Lightning protection Protection against static electricity


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GENERAL HAZARD CONTROL MEASURES

Use of National standards.

Observance of Rules & Regulations. Testing and inspection procedures.

Making and warnings.

Use of PPEs Electrical work procedures


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Training and education

Resuscitation techniques First aid of Fire Fighting.


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ELECTRICAL SAFETY RULES

(CHEMICAL INDUSTRIES)

IS 5571:1979IS 5571:1979 > Guide for selection of electricalequipment for hazardous area (1strevision)

IS 5572(Part 1):1944IS 5572(Part 1):1944 > Classification of hazardousarea for electrical installation.

ELECTRICAL INSTALLATIONS (CHEMICALELECTRICAL INSTALLATIONS (CHEMICALINDUSTRIES SCHEDULE XI PART II OF THE PFRINDUSTRIES SCHEDULE XI PART II OF THE PFR,1952,1952(Safety against dust,corrosion,flammability & explosibility)

DANGEROUS OPERATIONS (SECTIONDANGEROUS OPERATIONS (SECTION--87)87)

> Exposes any person to a serious risk of bodily injury,poisoning or disease.

Contd


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>High Noise: Noise induced hearing loss(notifiable disease no.22)

MANUFACTURE & REPAIR OF ELECTRICALMANUFACTURE & REPAIR OF ELECTRICALACCUMULATORS ( SCHEDULEACCUMULATORS ( SCHEDULE--IIIIII) > Hazardousprocess.

EXPLOSIVE OR INFLAMMABLE , DUST,GAS ETC.EXPLOSIVE OR INFLAMMABLE , DUST,GAS ETC.(SECTION(SECTION--37)37) > Process that produces, dust,gas,

fumes or vapours thats likely to explode onignition: All safety measure shall be taken toprevent any such explosion by effective enclosuresof all possible sources of ignition.


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ELECTRICAL SAFETYGENERAL RULES

The Factories Act,1948 & the Punjab Factories

Rules,1952:

LIGHTING ( SECTION 17 )LIGHTING ( SECTION 17 )> In every part offactory,provide & maintain sufficient & suitable lighting- Naturalor Artificial.

PRECAUTIONS REGARDING THE USE OF PORTABLEPRECAUTIONS REGARDING THE USE OF PORTABLEELECTRIC LIGHT ( SECTIONELECTRIC LIGHT ( SECTION--36A)36A)

> No portable light or portable tool of voltage exceeding 24V

shall be permitted for use inside a confined space.

>If flammables is likely to be present than no lamp or light otherthan flame-proof construction shall be permitted.


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PRINCIPLES OF EARTHING National regulations on electricity require that all

non-current carrying metallic parts of electricalequipment should be solidly connected to general

mass of earth with at least two earth connections.

Principle behind Earthing that any leakage currentwhich accidentally energizes non-current carrying

metallic parts should flow back through the generalmass of earth to the substation so the protectivedevices are actuated to cut off the supply as quicklyas possible.


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Requirements of Earthing

Earth connection should provide lowresistance path.

Setting & selection of protective devicesshould be such that it should operatefast to cut of the supply.


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What is Earthing ? Earthing means:

Direct connections of all non current

carrying parts of electrical equipments suchas metallic framework,motor body, cablearmoured, earth terminal of socket

outlet,transformer to a earth plate.*The earth plate is burried in ground whichhave a good electrical connection to thesurrounding earth.


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PURPOSE OF EARTHING1. To avoid electric shock to human

body.

2. To avoid risk of fire due to leakagecurrent through unwanted path.

3. To ensure that no current carrying

conductor rises to a potential wrtearth than its designed insulation.


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TYPES OF EARTHING1. Wire or strip earthing

2. Rod earthing

3. Pipe earthing

4. Plate earthing


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EARTHING RESISTANCE VALUES An healthy earth pit should have the value as

low as possible i.e 0.5 to 1 ohm.

Allowable earth resistance values for differentlocations:

4 ohm = Electrical system & metallic structures

7 ohm = Storage tanks 1 ohm = Main earth grid & pipe lines

* In our SRF (CB) all the 132 nos. of earth pitshave values between 0.5 to 0.9 ohm.


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STATIC ELECTRICITY When two electrically neutral but similarsurfaces come in contact,they transfer

electrons from one surface to another,bothbecomes electrically charged so that onesurface lose charge and other gaincharge.One will become +vely charged &

other vely charged and a spark dischargewill occur if strength increases.


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SOURCE OF GENERATION1. Liquids,gases flow in pipes,ducts, tanks,

trucks,vessels.

2. Liquids & gases under pressure fromnozzles.

3. Dragging a metal container along ainsulated floor.

4. Movement of driving or conveyer belts.5. Pneumatic conveying of plastic pellets &

blending.

6. Crystallization in an enamel coated vessel

using solvents with low conductivity.


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EFFECTS OF STATIC ELECTRICITY

Fire & Explosion

Discomfort & possible injury.

Contamination of process material


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ELECTROSTATIC IGNITIONFor static ignition,following conditions

must present:

1. Electrostatic charge generation must occur.

2. Means for static charges to accumulate.

3. The electrical field resulting from static

charge must be strong enough to provide aspark of sufficient energy to cause ignition.

4. An ignitable mixture of vapour-air or dust-airbe present.

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Electrical Safetyj 1365