TOPIC 2
ELECTRICAL SAFETY
LEARNING
OUTCOME
1
Describe the generation of
electricity
2
Explain how electricity is
trasmitted to users;
3
Determine hazards in the use of
electricity;
4
Describe on how to be safe in
using electricity; and
5
Discuss the legal requirements
pertaining to electrical safety
2.1 GENERATION OF ELECTRICITY
Electrical current: The flow of negatively charged particles called
electrons through an electrically conductive material, measured in Amperes.
Voltage: the potential difference between two points in the circuit, measured in Volts.
2 types of current:
• Direct current (DC) occurs when the current flows in one
constant direction. It usually comes from batteries, solar cells,
or from AC/DC converters. DC is the preferred type of power
for electronic devices.
• Alternating current (AC) occurs when the electric current
periodically inverts its direction.
2.1 GENERATION OF ELECTRICITY
• Our main concern is the generation of electricity that is required to power our homes and our
industries.
• Electricity is generated by generators, which are turned by reciprocating diesel engines, or by
turbines driven by water, wind turbines, gas or steam.
• The Three Gorges Dam in China and Bakun Dam in Bintulu both have a catchment area about
the size of Singapore, but the China HEP produces 22,000 MW of power, which is ten times
more than that produced by Bakun, as there is a vast difference between the capacity of the
rivers feeding the two dams.
• Wind turbines are rare in Malaysia as you need gale-force winds
blowing continuously for wind turbines to be productive.
• Nuclear power has been targeted since the 1970s but this plan was put
on the back burner when oil and gas were discovered in Malaysian
waters.
• The use of solar panels is also limited due to Malaysia’s equatorial
climate - rainfall is both heavy and frequent.
2.1 GENERATION OF ELECTRICITY
• Therefore, a large portion of the power in Malaysia (around 92 per
cent)is presently produced by steam turbine powered generators
using coal and gas as fuel.
• Hydroelectric power contributes 4.8 per cent, while oil and distillate
burning boilers generate 2.5 per cent of the power used in
Malaysia
2.2 TRANSMISSION OF
ELECTRICITY
• Electricity is generated at power plants. However this electricity has to be transmitted
all the way to our industries and homes before we can use it.
• We have several Independent Power Producers in this country, all of them selling
electricity to Tenaga Nasional Berhad (TNB).
• TNB then distributes the electricity to the industries and to consumers
B
A
• Transmission and distribution lines are not insulated.
• It is only at the final stage where electricity is distributed to consumers that the power
lines are insulated.
• Electricity is delivered using multi-coloured conductor wires,
• a neutral and a single wire earth return, and the colours may differ from country to
country.
C
D
2.3 HAZARDS IN THE USE OF ELECTRICITY
• Electricity related accidents: This happens when you switch on the
power and get a mild shock. The electric shock may not be enough to kill
or injure, but it is enough to cause you to jerk back. You stagger
backwards and fall to the floor. That fall may be enough to crack your
head and kill you. What is the problem? The terminal may have lost its
insulation properties; there may be a short circuit inside; there may be a
problem with grounding; and possibly your hands are wet.
• Electric shock and electrocution: this happens when you get a shock as
a result of touching a live wire, which means that the power was not
LOTO or even switched off.
2.3 HAZARDS IN THE USE OF ELECTRICITY
• Arc and arc flash. Welding uses an electrical source which provides low
voltage and a very high current. Arcing happens when an exposed
source of electricity (welding tip) comes near to a conductor substance
which is normally metal such as tools connected to groun and the
current jumps across the gap to complete the circuit, and in the
process, creates the arc. The arc temperature can easily reach 3,000 C,
which can easily blind your eyes.
• Fires and explosions. These are caused by arcing or sparking in the
presence of flammable material. It is interesting to note that electrical
arcs do not need oxygen, as electricity is just a massive flow of
electrons.
2.3 SAFE USE
OF ELECTRICITY
As far as possible, keep your distance
from live cables. Refer to Table 2.2;
Maintain your electrical equipment. The moment
you notice any signs of defect, or build-up of
heat, send the equipment for maintenance.
Allow only trained electrical technicians to
work on electrical equipment; and
Follow operating instructions when using
electrical equipment.
SYSTEMS OF
WORK
Have a safe operating procedure, by
carrying out a Job Hazard Analysis;
Have a Permit to Work (PTW) system in
place;
Carry out Lock Out Tag Out (LOTO)
before doing maintenance
Carry out a Tool Box Meeting (TBM) or
Pre-Job Briefing before any hazardous
job.
If you wish to generate a safe operating procedure for any job, start by
doing a Job Hazard Analysis (JHA). A Job Hazard Analysis is an analysis
of
all hazards that can manifest in every step of the job/task which includes
recommendations for appropriate controls. We can present the analysis
graphically as shown in Table 2.3.
PERMIT TO
WORK
How the job can be done safely (JHA)
What precautions have to be taken;
The PTW is not just permission to carry out
a dangerous job, but it also determines:
What foreseeable risks have to be
avoided;
Who is responsible for ensuring the same;
and
Who authorises the job.
LEGAL REQUIREMENTS
PERTAINING TO
ELECTRICAL SAFETY
The Electricity Supply Act 1990 (Act 447) is mainly concerned
with control of the supply of electricity
Safety and health issues are therefore left to the Occupational
Safety and Health Act 1994 (Act 514), which stipulates the
duties of employers, employees and manufacturers.
Under Section 15(2) (a) Employers have to ensure a plant and
system of work that is, as far as is practicable, safe and
without risks to health.
Section 15(2) (c) requires employers to provide information,
instruction, training and supervision to ensure safety and health
of employees at work.
Section 17 requires employers to ensure that other people
who are not their employees are not exposed to risks to their
safety or health.
Section 20 and 21 require manufacturers to ensure the plant or
substance supplied for use at work is safe and without risks to
health when properly used, and to conduct testing and inspection
to ensure user safety.
LEGAL REQUIREMENTS
PERTAINING TO
ELECTRICAL SAFETY
Section 24 requires employees to take reasonable care of the
safety of themselves and others, to use personal protective
equipment, and to cooperate with the management in
complying with Section 15(2) (c) above
The Factories and Machinery (Persons in charge) Regulations
1970 requires a competent Engine Driver to operate a Diesel