11 Electrical Safety

8/10/2019 11 Electrical Safety

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ELECTRICAL SAFETY


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Safety And Health OfficerCertificate Course

OBJECTIVES

At the end of this session, course participants

will be able :

To state definition of voltage, current and resistance

To explain 4 electrical hazards

To explain 2 principles of electrical safety

To state at least 4 factors that should be consider in

safe use of electricity

To identify electrical safety controls


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SCOPES

1. Definition

2. Electrical Installation

3. Electrical hazards and effects of electrical current

4. Principles of electrical safety

5. Safe use of electricity

6. Electrical safety controls

7. Conclusion


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INTRODUCTION

Electricity

- One of the main sources of energy and

has many uses to mankind (illuminate,

heating, cooling, running machines and

equipment


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Safety And Health Officer

Certificate Course

TERMINOLOGIES

Electricity is a form of energy produced from the flowof electrons. It is a general term that includes energy

related to electrical charges, whether static or

dynamic

3 factors that influence electricity are :a. Voltage (Volt) : Motive force of electrical energy

b. Current (Ampere) : Actual flow of electricity

c. Resistance ( Ohm) : Characteristics of a circuit

(path) where electricity is flowing and offersresistance to the current


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ELECTRICAL INSTALLATIONS

a) Circuit:-

i. Where electrical current flows

ii. Supplies a source of energy

iii. Equipped with conductors to enable

control of current flows


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b) Conductor:-

Contains metal that conducts electricitywithin the materials which is coveredwith an insulator (rubber) on the outside

c) Main Switch, Local and DistributionBoard

i. the main switch works to receive

electrical current supply from the sourceand switches (transfer) it to other partsthat requires it


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ii. It also stops electrical current flow the

circuit

iii. The Distribution Board contains the

main switch, circuit breakers and other

related switches. It receives electrical

current from an outside source beforeswitching/transferring


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d) Circuit Breaker

i. Works to break the circuit when an

overload occurs

ii. Avoids overheating that can cause

combustion

iii. Shaped like an enclosed switch

iv. Contains an automatic switch which

retracts from the on position to offposition when there is an overload of

electricity flow in the circuit


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e) Fuse

i. A thin piece of metal that will break

(when melted) if excessive current is en

encountered and causing the circuit to

break

ii. It will terminate the electricity supply


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f) External socket and plug

i. External socket

Entry to the circuit and allows tapping tolet electricity flow to the equipmentrequiring it

ii. Plug

Is connected to a flexible cable that

supplies electricity to the equipment,and is inserted into the external socketto complete another circuit


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ELECTRICAL HAZARD

a) Electrical Shocki. Occurs due to contact with a live wire together

with a flow through a human body

ii. It affects the normal functioning of the organsand nervous system such as causing weakmuscles and heart and respiratory systemfailure

iii. Death occurs if the heartbeat becomesabnormal and is interrupted for too long,insufficient flow of blood to the brain


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b) Lighting

ARC EYES

i. From UV light when looking at an electric arc or

welding flash

ii. Symptoms similar to conjunctivitis

iii. Temporary condition lasts for 3 or 4 days

iv. Does not affect contact lens


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c) Fire

i. From contact with an electric arc (ex: welding process)

ii. Overload of the conductor (ex: burning circuit)

iii. Discharge of static electricity

d) Electrostatic

i. Static electricity effects produced by an electric charge

trapped within an insulator. The charge can be transferred

whether within or outside the insulated object, or it can

concentrate on the conductor that is insulated from the earth

ii. Its characteristics : High voltage, low current

iii. If the static electricity charge is high, it can become a hazard

to a human and a risk of creating an ignition source incombustible surroundings


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EFFECTS OF ELECTRICAL CURRENT

Depend on:

a. Amount of electrical current

b. Bodys Resistance

c. Level of danger of electrocution shocks

d. Duration of flow


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OHMs LAW

Current (I) = Voltage (V)

Resistance (R)

Ampere : Volt

Ohm


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EXAMPLE:

For the effects of electrocution shock

Voltage (V) : 240 volt

Average body resistance (I) : 1000 ohm

Ampere (A) : 240 = o.24 amps

100


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KESAN SENTUHAN ELEKTRIK

National Safety Council -Indus. Safety & Health mgmt book

Current(mAmps)

Effects on humans

3 miliamps mild shock

7 miliamps Painful electrocution shock

20 miliamps Breathing difficulties

70 miliamps Risk of death

700 miliamps Body tissue scalding

3000miliamps Heart stop


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PRINCIPLES OF ELECTRICAL SAFETY

The principles of electrical safety are important in theprotection and prevention of people from electrocution

shock, fire and burning as a result of contact with

electricity

Two basic methods of prevention provide protectionfrom direct and indirect contact

a. Protection from direct contact

- provide insulation for the parts of the equipment

that can become electrically charged


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b. Protection from indirect contact

Provide effective earthing for isolated

metal that can become electricallycharged if the basic insulation fails


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SAFE USE OF ELECTRICITY

Considered factor:

Circuit protection

Isolating switch (insulator)

Maintenance and repair

Earthing

Protection


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Considered Factor:

Circuit Protection

All electrical equipment used must have

a fuse and circuit breaker that is suitable

to avoid the occurrence of overload


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Isolation Switch Must be labeled

Placed in a location that is easy to reach

All electrical equipments must have suchinsulators

Needs to be equipped with a lock

mechanism for locking when in the close(OFF) position.


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c) Maintenance and repair

i. prepare a safety work system when

performing maintenanceii. Formulate rules and perform

inspection/monitoring

iii. Implement a schedule or program for

maintenanceiv. Repairs must be carried out by certified

technicians

v. replacement of component such as fuse,

capacitor that is suitable

vi. Prepare access space around the

equipment to facilitate easy maintenance and

repair works


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d) Earthing

i. Earthing is required for all electrical

equipment

ii. Ensure that the earth circuit is

connected directly to earth (not through

a switch)


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Considered factor:Protection Install earth leakage protection such as

Residual Current Devices Install emergency stop switches, interlock

switches such as limit switch

Insulate all conductors

Install warning signage


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ELECTRICAL SAFETY CONTROLS

Government:The proper usage of electricity through

legislations and enforcement:

Electricity Supply Act 1990 Electrical Supply Regulations 1994

SIRIM Standards for Electrical Equipment

Occupational Safety and Health Act 1994(OSHA 1994)


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It is important to note that the OSHA 1994 that has

beenlegislated also outlines the obligations of employers,

manufactures, designers, producers and workers,

among which are:

a. On the part of employers

i. have a work safety system

ii. Provide training, instruction and information

to workersiii. Create preventive protective measures for

workers and contractors


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b. On the part of manufactures,

designers, producers

Have inspections, tests on the goods

produced to ensure the safety of users

c. On the part of workers

Comply to the rules that have been

established by the employers to ensure

safety at work


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CONCLUSION

Serious attention must be given to electrical hazards,seeing its vast spectrum of effects and results on

users

Two methods of prevention that have been outlined

are protection from direct contact and indirect contact The government has also formulated several statutory

provisions related to electrical safety, towards

ensuring the safety of users

Safe use of electricity also looks at several preventivemeasures that may be taken.

Documents

11 Electrical Safety