1. Chapter 3 PHYSICAL INJURY AND CONTROLS 3.2 Electrical Safety
BWU Occupational Safety & Health
Presented by
Dr. Mohd Nasrull Abdol Rahman

2. Learning Outcomes:
At the end of this section, students will be able to:
Explain the definition of current, voltage and resistant
Explain four electrical hazards
Plan two basic preventive steps related to electrical safety
Classify at least four factors that are normally considered in safe electrical usage (control measure)
Relate legal provision related to electrical safety

3. Electric
A type of energy. An efficient and easily available energy
Usage: Lighting, heating, energy application (oven, furnace etc.)
Terminology:
Electric is an energy resulted from conduction of electrons. It is a general term which includes the energy related to electric charges whether static or dynamic
Factors influencing electrical energy:
Voltage (Volt) : A representation of electrical potential energy
Current (Ampere): Represents the flow of electrons through a conductive material
Resistant (Ohm) : The characteristic of a circuit or path in which electric flows and the path offer a resistance to the flow

4. The advantages of electrical energy
Cheap
Clean
Easy to use
No storage is required
The characteristics of electrical energy
It cannot be seen
It cannot be heard
It cannot be smelled

5. The electrical installation includes:
Electric circuit
Conductors
Main switches, local switches and distributing board
Circuit breakers
Fuses
Socket and plug
The electric circuits are:
The path where the electric current flows
It provides the source of electrical energy
It includes the conductors to enable the current to be controlled

6. The conductors:
Includes metal component that allows the conductions of electricity at the center part and insulation material (rubber) at the outer part.
Main switches, local switches and distributing board
Main switches function to receive electric current from the electricity source and distribute it to other areas that need it.
Main switches and local switches also functions to stop the flow of electric current in a circuit.
Distributing board provides a location for the main switches, circuit breakers and other related switches. It receives electric current from the external source before distributing it to other area.

7. circuit breakers:
Function when there are excess electricity load
To prevent excess heat that can cause fire
In the form of closed switch
It has a mechanism to release the switch from ‘on’ position to ‘off’ position if excess current flows through the circuit
Fuses
A piece of thin metal that melts at the current value below the excessive current flow
It stops the electricity supply
Output socket and plug
Output socket enters a circuit when tapping is performed and it allows electrical energy to be supplied to equipment
Plug is connected to the flexible cable supplying electrical energy to equipment. It is inserted into the output socket and hence establishing another circuit

8. The effect of electrical hazards
Electric shock
Excessive brightness
Fire
Static electricity
Normally from life wire to earth wire
Causing muscular contraction shortened and thickening (cramp or spasm)
Can disturb the normal heart response
Can cause breathing failure

9. Excessive brightness (from arc eyes)
From ultra violet rays when looking at the electrical ark or the welding light.
Symptom like conjunctivitis
Temporary symptom will continue for 3 or 4 days
It makes the contact lens not effective
Fire
It is caused by the contact of electrical arc resulted from conductor short circuit or excessive equipment electrical load
Or the release of static electric charge

10. Static Electricity
It is the effect of trapped electric charge in the insulator. This charge can be distributed to either inside or outside of the insulated object. Or it can be concentrated on a conductor which is insulated from the earth.
High voltage, low current
Can result to electric shock and igniting source within flamable environment (if the static charge is high)

11. Electrical Safety
The effect of electric current varies depending on:
Age
Sex
Body electrical resistance
Health condition
The amount of flowing current and its voltage
The seriousness of the electric shock
The total time of the current flow

16. Principles of Electrical Safety
The main objective is to protect human from electric shock, fire and burning effect resulted from contact with electricity
Two fundamental preventive steps are:
Prevention from direct contact with electricity
Prevention from indirect contact with electricity
Provides insulator to parts of equipment that has potential to release electric charge
Provides effective earthling to isolate metals that could discharge electricity if main insulation fails.

17. Safe electricity usage
Factors to consider:
Circuit protection
Isolation switches
Maintenance and repair of damaged equipments
Earthling
Protection
All electrical equipments must be equipped with appropriate fuses and circuit breakers to prevent excessive loads.

18. Safe electricity usage
Isolation switches
All isolation switches must be labeled
Must be easily assessable at the working floor
Must be installed at each individual machine
Equipped with locking facility when it is ‘off’ position
Maintenance and repair of damaged equipments
Establish safe work system during maintenance
Establish related rules and inspection/monitoring
Establish maintenance program/schedule
Provides access area surrounding the equipments for maintenance and repair purposes
Executed by certified/competent electrician
Replacement of components such as fuses or capacitor must be of appropriate and correct type.

19. Safe electricity usage
Earthing
Must be provided for all electrical equipments
Earth circuit must be directly connected to earth (not going through switches)
Protection
Provide earth leakage protection such as Residual Current Devices.
Provide emergency stop switch and interlock switch (example: limit switches)
Insulate conductors
Installation of safety signboards.

20. Electrical safety controls
Establishing laws, rules and enforcement by the government
Electricity Supply Act 1990
Electricity Supply Regulations 1994
SIRIM standards
Occupational Safety and Health Act 1994 (OSHA 1994):

21. Electrical safety controls
Employers’ responsibility:
Establish Safe Work System
Provide training, information and instruction
Establish preventive and protective action plan for employees and contractors.
Equipment manufacturer, supplier and designer:
Establish testing and inspection to ensure users safety
Employees’ responsibility:
Follow the rules established by the employer.

22. Conclusions
Electricity has many hazards that can affect the employees’ safety and health.
There are two fundamental preventive steps that can be taken to protect human from electrical hazards.
This is followed by executing safe electricity usage discussed in the section.
The government also controls the safe electricity usage by establishing several act and regulations.

23. Class Activities
Explain the definition of current, voltage and resistant.
Explain four electrical hazards.
Plan two basic preventive steps related to electrical safety.
Classify at least four factors that are normally considered in safe electrical usage.
Relate legal provision related to electrical safety.

24. Group Discussion (Discuss among the group members)
Identify FIVE (5) types of electrical hazards at etc.
List down the effect of electrical hazards (such as Electric shock, Excessive brightness, Fire, Static electricity etc)
List down preventive steps/control measure that can be taken to protect human from electrical hazards.