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ELECTRICAL SAFETY IN

POWER DISTRIBUTION

BY

EZE, MONDAY NDUBUISI

08084501883, 07068301351

IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE

MEMBERSHIP OF INSTITUTE OF SAFETY PROFESSIONALS OF

NIGERIA

SEPTEMBER, 2014.

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ABSTRACT

While there are many circumstances that can lead to an electrical accidents, it is helpful to identify

and document known hazardous conditions that can occur in electrical facilities and equipment.

Conditions that can be reproduced in a laboratory, intended to duplicate real-life conditions, can be

used to increase knowledge of the possible hazards and as a guide for manufacturers to develop safer

and more fire resistant electrical systems. The need for electrical energy which has grown drastically

high, due to advancement in technology, which are mainly electrically driven. This advancement has

equally bring about high electrical accidents, due to unsafe working condition and unsafe practices

at work. Hence, the need to reduce the accident at work become a necessity in order to increase

productivity and making environment safe for the workers. The first stage in electrical hazard effect

management process is to identify the associated hazards in different tasks related to electrical

engineering and other industries that electrical power is of great need to drive the machineries. After

this has been done, it is pertinent to evaluate or access the extent of the damage the hazard could

cause, this will enable the operators of the facilities to put in place control measures base on

hierarchical level of controls, in the to enhance the control measures a recovery measures is put in

place as back up, in case the control measure fails.

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ACKNOWLEDGEMENT

With much pleasure and gratitude, I extend my sincere thanks to the Almighty God and all those

that helped me in all the activities leading to this project, both in their individual and institutional

Capacities. I will forever be indebted for their cooperation and support. It is hardly possible to

thank them individually here.

My heartfelt gratitude goes to my sponsor, Mr. Sunday Akinbode Ogungbe, Managing Director

of Paper House Limited for his guidance, kind gestures and his support to me .Special thanks also

go to Dr. Wilson Arikpo , Public Relation Officer of Institute of Safety Professionals of Nigeria

(ISPON). I wish to thank the Head of Electrical/ Electronics Engineering Department, Prof

Adegbenro and the staff of University of Lagos, Electrical Department.

My profound gratitude goes to my mother, Mrs. Elizabeth Eze for her prayers and financial

Support. Thank You All!!

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LIST OF FIGURES

Figure 1……………………………………………………Electrical Burn

Figure 2……………………………………………………………...A Fuse

Figure 3……………………………………………………Circuit Breaker

Figure 4…………………………………...Arc Fault Circuit Interrupters

Figure 5………………………………Ground Fault Circuit Interrupters

Figure 6…………………………………..Earth Leakage Circuit Breaker

Figure 7………………………………………………….Guarding System

Figure 8…………………………………………………..Earthing System

Figure 9………………………………………………………Disconnector

Figure 10…………………………………………………...House Keeping

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CHAPTER 1

ELECTRICITY

1.1 Introduction

Electricity is the set of physical phenomena associated with the presence and flow of electric

charge. Electricity gives a wide variety of well-known effects, such as lightning, static electricity,

electromagnetic induction and electrical current. In addition, electricity permits the creation and

reception of electromagnetic radiation such as radio waves.

In electricity, charges produce electromagnetic fields which act on other charges. Electricity occurs

due to several types of physics:

electric charge: a property of some subatomic particles, which determines their

electromagnetic interactions. Electrically charged matter is influenced by, and produces,

electromagnetic fields.

electric potential: the capacity of an electric field to do work on an electric charge, typically

measured in volts.

electric current a movement or flow of electrically charged particles, typically measured in

amperes.

electromagnets: Moving charges produce a magnetic field. Electrical currents generate

magnetic fields, and changing magnetic fields generate electrical currents.

electric field: is created by a charged body in the space that surrounds it, and results in a

force exerted on any other charges placed within the field.

electrochemistry: The ability of chemical reactions to produce electricity, and conversely

the ability of electricity to drive chemical reactions has a wide array of uses.

electric circuit: is an interconnection of electric components such that electric charge is

made to flow along a closed path (a circuit), usually to perform some useful task.

electric power: electric power is the rate at which electric energy is transferred by an

electric circuit. The SI unit of power is the watt, one joule per second.

electronics: electronics deals with electrical circuits that involve active electrical

components such as vacuum tubes, transistors, diodes and integrated circuits, and

associated passive interconnection technologies.

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1.2 Problem Statement

Hospital Emergency Rooms provide life-saving measures to tens of thousands of individuals

injured/maimed/impaired as a direct/indirect result of the effects of electric current passing through

their bodies usually through a careless act. Over a thousand individuals are electrocuted annually.

Electrical accidents in the home and on-the-job are initiated as a result of improper use and care

of electrical equipment, extension cords, and plugs. Causes for these events include inattention

through repetition, unexpected and inexperience and overconfidence. We can eliminate a large

percentage of these injuries and death through the application/use of safe tool/electrical practices.

1.3 Objectives

The aim of the study of electrical safety covers both the applications of electrical energy at

industrial and domestic level. The objectives are

To identify hazards that could lead to electrical accident

To access the hazards surrounding electrical works/task

To put in place control measures necessary to curtail the electrical accident likely to

occur.

To be able to put in place recovery measures in case the control measures fails

To educate workers on safety tips in an electrical environment

1.4 Motivation

The passion to research on electrical safety can be link to professional experience in defunct Power

Holding Company of Nigeria, where I worked as an Industrial Trainee Student in Operation and

Maintenance department, Protection, Control and Metering department where safety is imperative

even though it was not fully practice.

1.5 Scope of Study

The project cover details about electricity from the history, applications , the hazards in electricity,

management of electrical hazards, application of Hazards Effect Management Process (HEMP)

to electrical hazards, safety tips and practices that can enhance safety of workers , managing the

risks of electrical work, electrical working a confined spaces , safe work method statement, low

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voltage isolation and access , safety in restoring power, risk controls on energized and de-energized

electrical works, importance of earthing system to electrical safety, proper house keeping.

1.6 Brief History

Electrical phenomena have been studied since antiquity, though progress in theoretical

understanding remained slow until the seventeenth and eighteenth centuries. Even then, practical

applications for electricity were few, and it would not be until the late nineteenth century that

engineers were able to put it to industrial and residential use. The rapid expansion in electrical

technology at this time transformed industry and society. Electricity's extraordinary versatility

means it can be put to an almost limitless set of applications which include transport, heating,

lighting, communications, and computation. Electrical power is now the backbone of modern

industrial society.

1.7 Applications

In electrical engineering, electricity is used for:

• electric power where electric current is used to energise equipment;

• electronics which deals with electrical circuits that involve active electrical components

such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive

interconnection technologies.

1.8 The Hazards of Electricity

Electricity is invisible - this in itself makes it dangerous. It has great potential to seriously injure

and kill. The average can receive critical injuries as a result of even very short exposures to

everyday 240-volt single-phase alternating current supply voltages. Major electrical risks exist

when insulation protection is not maintained in a safe condition or is placed in a hostile

environment causing it to fail.

It must also be remembered that there are other electrical hazards and risks with potentially fatal

consequences where a residual current device or safety switch might be inoperative. This can occur

when the electrical plant has a fault and there is contact by the operator between the active

(positive) and the neutral (negative) conductors forming a short circuit through the body with no

leakage to earth, and therefore insufficient residual current for the RCD to operate. It is therefore

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necessary to manage workplace electrical safety as an integral part of day-to-day operations in

order to ensure the integrity of electrical installations and electrical plant.

1.9 Management of Electrical Hazards

General principles One of the general principles in implementing the Occupational Health Safety

and Welfare Regulations, 1995, is ‘hazard management’. Hazard management consists of four

stages. Those stages are hazard identification, risk assessment and risk control and recovery

measures.

1.9.1 Hazard Identification

A hazard is something that has the potential to harm the health, safety and welfare of people at

work. Examples of electrical hazards that may be found in the workplace include frayed flexible

supply cords, cracked electrical plant covers, flexible supply cords which have been run over by

vehicles, electrical plant used in wet areas and electrical plant which is moved frequently such as

vacuum cleaners. These are all considered electrical hazards. To identify hazards to health, safety

and welfare:

• Check records of injuries and incidents (including near misses) that have occurred in the

workplace or in other similar workplaces.

• Read publications such as OHSW and Electrical Regulations, Codes of Practice, Guidelines

from IEEE.

• Conduct walk-through inspections of the workplace using a checklist to identify potential

electrical hazards. This checklist may include, but is not limited to, checking all flexible supply

cords, electrical plant, the way the electrical plant is used and the areas that it is used in.

• Ask employees if they have ever experienced problems with electrical plant to identify

electrical hazards. Hazard identification should be an integral part of workplace culture. This

involves regular workplace inspections in consultation with employee representatives and

encouraging employees to report any hazardous situations that may occur in the workplace.

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1.9.2 Risk Assessment

When hazards have been identified, the risk associated with each hazard needs to be assessed to

evaluate the probability and consequences of injury, illness or disease arising from exposure to an

identified hazard or hazards. When performing a risk assessment consider the following:

• the nature of the hazard

• how it may affect health and safety

• the likelihood that the hazard will cause injury, illness or disease, (how much, how often and

how long employees are exposed).Put simply, the identification of a frayed and worn electrical

cable on an appliance is the identification of a hazard. An appreciation of the associated risk, that

is, a risk that is likely to cause serious injury or a fatality, is an example of risk assessment. Clearly

such a situation would require immediate action, which would include removing the faulty item

from service until it can be replaced or repaired. This is a form of risk control, which will be

covered in more detail in the following stage. The risk assessment also takes into account the way

that the work is organised, the layout and condition of the work environment, the training and

knowledge needed by the person to perform the work safely and the type of control measures that

are available. The assessment of risk is a process of gathering information and making decisions.

There is no single correct answer, as people will make certain decisions about the risk because

they have different ideas about what is acceptable. For this reason it is important that those who

will be affected by the decisions made (the employer, relevant employees and their representatives)

should be involved in the assessment.

1.9.3 Risk Control

When hazards have been identified and the risks assessed, appropriate control measures should be

developed and implemented. The aim is to eliminate or minimise the risk. There are many ways

for employers to control risks to health and safety in the workplace. As far as possible a hazard

should be controlled at its source rather than trying to make the employee ‘work safely’ with

dangerous electrical plant or in a dangerous environment. Controlling the hazard at the source is

much more effective in the prevention of injury, illness or disease. To do this, action needs to be

taken to control risks through a preferred sequence of risk control programs.

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1.9.4 Recovery Measures

Once the control measures have been implemented it is important to evaluate how effective those

measures have been. This is performed by simply re-assessing the risks associated with the hazard

and establishing whether the controls have eliminated or minimised the risk of injury, illness or

disease. And if the control measures fail, contingency plan are on ground such as:

provision of first aid kits

emergency response team such as ambulance service

fire fighting equipment such as fire extinguisher.

Regular fire drill at the operational station.

Training and continuous re- training of staffs

1.9.5 Review

A review of the hazard management process should be performed at regular intervals. This can be

part of a regular inspection or when work practices or the work environment changes, to ensure no

new hazards have been introduced.

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CHAPTER 2

ELECTRICAL HAZARDS

2.1 Introduction

Electrical hazards are caused by the improper use of machinery or apparatus, electrical outlets,

electrical equipment, such as cables and power cords the improper maintenance of apparatus,

outlets, and electrical equipment. When used or maintained improperly, electrical equipment or

devices can overheat or produce electrical fires. Frayed cords or exposed wires can easily electrify

you or your students. Causes of hazards are:

apparatus with deteriorated power cord insulation

a bent or broken prong on a plug

a broken prong on a plug protruding from an outlet

an overloaded circuit

flammable fumes near electrical apparatus

metal tools used near energized conductors

dangling jewelry near an energized conductor

a circuit that someone is working on with both hand water spill on electrical equipment

2.2 Types of Electrical Hazards are, namely

Electrical Shock

Electrical Burns

Fall

Electroocution

Electrical Fire

Arc blast

Heart failure

2.2.1 Electrical Shocks

Electricity travels in closed circuits, and its normal route is through a conductor. Electric shock

occurs when the body becomes a part of the electric circuit. The current must enter the body at one

point and leave at another. Electric shock normally occurs in one of three ways. Individuals-while

in contact with the ground- must come in contact with both wires of the electric circuit, one wire

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of an energized circuit and the ground, or a metallic part that has become "hot" by contact with an

energized conductor. The metal parts of electric tools and machines may become energized if there

is a break in the insulation of the tool or machine wiring. The worker using these tools and

machines is made less vulnerable to electric shock when there is a low-resistance path from the

metallic case of the tool or machine to the ground. This is done through the use of an equipment

grounding conductor a low resistance wire that causes the unwanted current to pass directly to the

ground, thereby greatly reducing the amount of current passing through the body of the person in

contact with the tool or machine. If the equipment grounding conductor has been properly

installed, it has a low resistance to ground, and the worker is protected.

Severity of the Shock

The severity of the shock received when a person becomes a part of an electric circuit is affected

by three primary factors: the amount of current flowing through the body (measured in amperes),

the path of the current through the body, and the length of time the body is in the circuit. Other

factors that may affect the severity of shock are the frequency of the current, the phase of the heart

cycle when shock occurs, and the general health of the person. The effects of electric shock depend

upon the type of circuit, its voltage, resistance, current, pathway through the body, and duration of

the contact. Effects can range from a barely perceptible tingle to immediate cardiac arrest.

Although there are no absolute limits or even known values that show the exact injury from any

given current, the table shows the general relationship between the degree of injury and amount

of current for a 60-cycle hand-to-foot path of one second's duration of shock.

Electrical hazards can burn equipment and cause a fire in your Classroom or house these hazards

can also cause serious injuries to you or your students. Specifically, current passing through a body

may produce one or more of the following symptoms:

Shock should not be confused with electric shock. Shock is an excitation or disturbance of

the normal function of nerves or muscles.

Involuntary muscle reaction: a person who experiences an electric shock may not be able

to control her or his muscles. In addition, muscles that a person normally does not control,

such as the heart, may operate abnormally.

Muscle paralysis: an electric shock may prevent muscles from moving (for example, arm

muscles cannot flex) or operating (for example, the heart cannot pump blood).

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Burning of tissue and organs Tissue and organs may be burned so badly that they

hemorrhage.

Death (electrocution): Death can result from electrocution, which is caused by electric

shock.

2.2.2 Electrical Burns

Electrical burns can be caused by a variety of ways such as touching or grasping electrically live

objects, short-circuiting, inserting fingers into electrical sockets, and falling into electrified

water. Lightning strikes are also a cause of electrical burns, but this is a less common event.[8] With

the advances in technology, electrical injuries are becoming more common and are the fourth

leading cause of work-related traumatic death. One third of all electrical traumas and most high-

voltage injuries are job related, and more than 50% of these injures result from power line contact.

Electrical burns can be classified into six categories, and any combination of these categories may

be present on an electrical burn victim:

Low-voltage burn. A burn produced by contact with a power source of 500 volts or less is

classified as a low-voltage burn. The current at this voltage is not enough to cause tissue

damage along its path except at the contact site. This type of burn may be mild, superficial, or

severe depending on the contact time.

High voltage burn. This burn is very severe as the victim makes direct contact with the high

voltage supply and the damage runs its course throughout the body. Exterior injuries are

misleading as most of the damage occurs underneath the skin. In this case, sub dermal tissues

are severely damaged.

Arc burn:No contact is required with an arc burn as the electricity ionizes air particles to

complete the circuit. The heat generated can be as high as 4,000 degrees Celsius - hot enough

to vaporize metal and ignite a victim’s clothing. A form of explosion dissipates excess energy

from the arc. In addition, a high-amperage arc can produce a pressure wave blast in excess of

1000 pounds per square inch of pressure. This can throw the victim and cause severe injuries.

Flash burn. Flash burns are caused by electrical arcs that pass over the skin. The intense heat

and light of an arc flash can cause severe burns. Although the burns on the skin are largely

superficial and cover a large area, tissues beneath the skin are generally undamaged and

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unaffected. This typically occurs when the frequency of the AC current is significantly higher

than the 50 or 60 Hz used in land-based electrical distribution systems (such as in aircraft).

Flame burn. Flame burns are caused by Low-voltage burn. A burn produced by contact with

a power source of 500 volts or less is classified as a low-voltage burn. The current at this

voltage is not enough to cause tissue damage along its path except at the contact site. This type

of burn may be mild, superficial, or severe depending on the contact time. .

Oral burns. This is caused by biting or sucking on electrical cords, and it most commonly

happens to children. Electrical current typically passes from one side of the child’s mouth to

the other, possibly causing deformity.

Figure 1: electrical burn

The most common shock-related injury is a burn. Burns suffered in electrical accidents may be of

three types: electrical burns, arc burns, and thermal contact burns. Electrical burns are the result of

the electric current flowing through tissues or bone. Tissue damage is caused by the heat generated

by the current flow through the body.

Electrical burns are one of the most serious injuries you can receive and should be given immediate

attention. Arc or flash burns, on the other hand, are the result of high temperatures near the body

and are produced by an electric arc or explosion. They should also be attended to promptly.

Finally, thermal contact burns are those normally experienced when the skin comes in contact with

hot surfaces of overheated electric conductors, conduits, or other energized equipment.

2.2.3 Fall

Each employee on walking/working surfaces must be protected from falling through holes

(including skylights) more than six feet above lower levels. Each employee on a walking/working

surface must be protected from objects falling through holes (including skylights) and from

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tripping in or stepping into holes (including skylights) by covers and falling from height above the

ground level . Wall openings: Each employee working on, at, above, or near wall openings

(including those with chutes attached) where the outside bottom edge of the wall opening is six

feet or more above lower levels and the inside bottom edge of the wall opening is less than 39

inches above the walking/working surface, must be protected from falling. Established floors,

mezzanines, balconies, and walkways. Each employee on established floors, mezzanines,

balconies, and walkways, with an unprotected side or edge six feet or more above a lower level,

must be protected from falling. Each employee at the edge of an excavation six feet or more in

depth must be protected from falling when the excavations are not readily seen because of plant

growth or other visual barrier. Each employee at the edge of a well, pit, shaft, and similar

excavation six feet or more in depth must be protected from falling. Each employee must be

protected from falls into or onto dangerous equipment, regardless of the fall distance. When an

employee is exposed to falling objects, the employer must have each employee wear a hard hat

and must implement an additional measure of protection such as erecting toe boards, screens, or

guardrail systems; or erect a canopy structure; or barricade the area and prohibit employees from

entering the barricaded area.

2.2.4 Electrical Arcing

In addition to the explosive blast, called the arc blast of such a fault, destruction also arises from

the intense radiant heat produced by the arc. The metal plasma arc produces tremendous amounts

of light energy from far infrared to ultraviolet. Surfaces of nearby objects, including people, absorb

this energy and are instantly heated to vaporizing temperatures. The effects of this can be seen on

adjacent walls and equipment - they are often ablated and eroded from the radiant effects.

2.2.5 Electrocution

Electrocution is death caused by electric shock, either accidental or deliberate. The word is derived

from "electro" and "execution", but it is also used for accidental death. The term "electrocution,"

coined about the time of the first use of the electric chair in 1890, originally referred only to

electrical execution and not to accidental or suicidal electrical deaths. However, since no English

word was available for non-judicial deaths due to electric shock, the word "electrocution"

eventually took over as a description of all circumstances of electrical death from the new

commercial electricity.

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2.2.6 Electrical explosion

A high current electrical fault can create an 'electrical explosion' by forming a high

energy electrical arc which rapidly vaporizes metal and insulation material. This arc flash hazard

is a danger to persons working on energized switchgear. Also, excessive magnetic pressure within

an ultra-strong electromagnet can cause a magnetic explosion.

2.2.7 Electrical Fires

Electrical fires are fires involving potentially energized electrical equipment. The US system

designates these "Class C"; the Australian system designates them "Class E". This sort of fire may

be caused by short-circuiting machinery or overloaded electrical cables. These fires can be a severe

hazard to fire fighters using water or other conductive agents: Electricity may be conducted from

the fire, through water, to the fire fighter's body, and then earth. Electrical fire have caused many

firefighter deaths.

Electrical fire may be fought in the same way as an ordinary combustible fire, but water, foam,

and other conductive agents are not to be used. While the fire is or possibly could be electrically

energized, it can be fought with any extinguishing agent rated for electrical fire. Carbon dioxide

CO2, FM-200 and dry chemical powder extinguishers such as PKP and even baking soda are

especially suited to extinguishing this sort of fire. PKP should be a last resort solution to

extinguishing the fire due to its corrosive tendencies. Once electricity is shut off to the equipment

involved, it will generally become an ordinary combustible fire.

.

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CHAPTER 3

MANAGING THE RISKS OF ELECTRICAL WORK

3.1 What Is Electrical Work?

Electrical work means connecting electricity supply wiring to electrical equipment or

disconnecting electricity supply wiring from electrical equipment. Installing, removing, adding,

testing, replacing, repairing, altering or maintaining electrical equipment or an electrical

installation. In the course of carrying out any electrical work either low or high voltage, hazard

management process should be carried out on the job/task to be done. They are;

identify the hazards.

access the risks

A risk assessment involves considering what could happen if someone is exposed to a hazard and

the likelihood of it happening. Risks associated with electrical work may arise from:

the properties of electricity, electricity is particularly hazardous because electrical currents

are not visible and do not have any smell or sound.

how and where the electrical work is carried out. Electrical work may be carried out in

difficult conditions, including in wet weather conditions, confined spaces and in

atmospheres that present a risk to health and safety from fire or explosion.

the competence of the persons carrying out the electrical work.

If energised or ‘live’ electrical work is proposed to be carried out, a risk assessment must be

undertaken before the work starts and it must be carried out by a competent person and recorded.

The following risk factors associated with carrying out electrical work should be considered:

sources of electrical risks, including energy levels at the workplace

the nature of the electrical work to be carried out\

potential or actual high fault current levels (i.e. risks associated with arc flash)

availability of isolation points

work practices

the type of plant, machinery and equipment to be used

availability of suitable test instruments

availability of properly rated PPE

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the workplace and working environment, for example:

wet weather conditions in and around trenches, pits and underground ducts

ladders, scaffolds, portable pole platforms, elevating work platforms, poles and towers

3.2 Electrical Work in a Confined Spaces

The followings must be considered before electrical work is carried out in a confined space;

ability to safely rescue persons.

the competence of people carrying out the work, noting that licensing requirements may

apply for the electrical work under local electrical safety laws.

Also consider individual workers’ needs, for example;

Is the worker experienced in, and have they been properly trained for, the working

conditions?

Is the worker physically fit for the proposed work, for example are they able to climb to

heights to work on an overhead conductor or are they mentally alert and not fatigued?.

Does the worker have a visual or hearing impairment, for example do they have a visual

colour deficiency or hearing loss?

Does the worker take any medication that may increase their vulnerability to work in

electrical environments?

Is the worker working excessively long hours?

Does the worker suffer from claustrophobia?

3.3 Control the Risks

Once hazards have been identified and the risks assessed, appropriate control measures must be

put in place. Electrical safety generally depends on appropriate training, work planning, and

correct testing procedures and techniques.

The ways of controlling risks are ranked from the highest level of protection and reliability to the

lowest. This ranking is known as the hierarchy of risk control. You must work through this

hierarchy to choose the control that most effectively eliminates or minimises the risk in the

circumstances, so far as is reasonably practicable. This may involve a single control measure or a

combination of two or more different controls.

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3.3.1 Elimination

The most effect control measure is to remove the hazard or hazardous work practice. For example,

working de-energised rather than energised eliminates significant electrical risks. That is why the

World Health Safety Regulations prohibit energised electrical work subject to certain exceptions.

3.3.2 Substitution

Replacing a hazardous process or material with one that is less hazardous will reduce the hazard,

and hence the risk. For example, it may not be reasonably practicable to eliminate energised

electrical work altogether; however, even if it is necessary (for one of the legally permissible

reasons) to work on an energised electrical part, it may be possible to de-energise the surrounding

parts.

3.3.3 Isolation

Preventing workers from coming into contact with the source of the electrical hazard will reduce

the relevant risks.

3.3.4 Engineering controls

Use engineering control measures to minimise the risk, for example insulation, guarding and

installing residual current devices to prevent electric shock.

3.3.5 Administrative controls

Administrative controls involve the use of safe work practices to control the risk, for example the

provision of suitable and adequate training, establishing exclusion zones, use of permits and

warning signs.

3.3.6 Personal protective equipment (PPE)

PPE includes protective eyewear, insulated gloves, hard hats, aprons and breathing protection. The

PPE should be rated for the work to be done. If working on energised equipment, the PPE must be

able to protect the user from the maximum prospective energy available at the work site.

Administrative controls and PPE do nothing to change the hazard itself. They rely on people

behaving as expected and require a high level of supervision. Exclusive reliance on administrative

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controls and PPE must only occur where other measures are not reasonably practicable or as an

interim control while the preferred control measure is being implemented.

However, administrative controls such as procurement and personnel policies and procedures are

very important in relation to electrical risks, as they will help to ensure that electrical work is

carried out by a qualified electrician as required by law.

Review the control measures: You should check that your chosen control measure does not

introduce new hazards.

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Chapter 4

RISK CONTROLS – WORKING ON DE-ENERGISED

4.1 Working on De-energised Electrical Equipment

Electrical work (whether energised or de-energised) must only be carried out by appropriately

licensed or registered electrical workers. For more information about the applicable electrical

licensing or registration laws contact the local regulator in the relevant jurisdiction.

General principles – verification of de-energised electrical equipment

These provisions do not apply to work carried out by or on behalf of electricity supply authorities

on the electrical equipment, including line-associated equipment, controlled or operated by the

authority to generate, transform, transmit or supply electricity. This exemption does not extend to

the electricity generation sector.

A person conducting a business or undertaking carrying out electrical work must ensure that,

before electrical work is carried out on electrical equipment, the equipment is tested by a competent

person to determine whether or not it is energised.

The person conducting a business or undertaking must ensure that:

each exposed part is treated as energised until it is isolated and determined not to be

energized.

each high-voltage exposed part is earthed after being de-energised.

A person conducting a business or undertaking must ensure that electrical equipment that has been

de-energised to allow for electrical work to be carried out cannot be inadvertently re-energised.

The safe work procedure ‘TEST FOR ‘DEAD’ BEFORE YOU TOUCH’ must be applied at all

times. Even if the electricity supply is believed to have been isolated, it must be assumed that all

conductors and electrical components are energised until they have been proven de-energised.

Testing for ‘dead’ must be undertaken as appropriate for the duration of the electrical work. Testing

is undertaken prior to touching, taking into account all relevant factors including the nature of the

conductor, nature of the isolation, nature of work, if there has been a change or the area has been

left idle (unattended) for a period.

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The testing method (including the tester used) must be safe and effective. The electrical worker

carrying out the testing must understand testing procedures and be competent in the use of the

tester.

4.2 Safe Work Method Statements

A person conducting a business or undertaking must ensure that electrical work on energised

electrical equipment is carried out in accordance with a safe work method statement.

Safe work method statements are required in relation to prescribed ‘high risk construction work’,

in addition to energised electrical work.

4.3 Work on Cables (including Cutting Cables)

Where work is to be carried out on a cable, the cable should be de-energised. Cables must be

treated as energised and the procedures for working on energised electrical equipment followed

until positive tests can be made that prove the cable is de-energised. If the cable’s connections are

exposed the connections and attached live parts should be proved to be de-energised and identified

before work starts. Cutting cables presents particular risks. Both ends of the cable should be

checked for isolation prior to cutting. Schematic diagrams or ‘as built’ diagrams should be checked

carefully to establish secondary or metering circuits in multi-cored cables prior to cutting.

Additional precautions should be taken to ensure insulated or covered cables are de-energised,

whether the cables are low voltage, high voltage or control cables. For example, the action of

cutting a multi-core control cable is likely to create a risk if secondary current from a current

transformer is present. This risk may not be initially apparent; that is, the cable cutters may not be

damaged when the cable is cut. A high voltage may develop across the open-circuited secondary

winding causing an electric shock, arcing or a fault at a later stage.

4.4 Low Voltage Isolation and Access

Working de-energised on low voltage electrical equipment or circuits requires the electrical

equipment or circuits to be effectively isolated from all relevant sources of electricity supply. This

may be done using opening switches, removing fuses or links, opening circuit breakers or

removing circuit connections.

The standard steps in low voltage isolation are:

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Consulting with the person with management or control of the workplace and notifying any other

affected persons as appropriate.

4.4.1 Identifying the circuits requiring isolation

Disconnecting active conductors from the relevant source(s), noting there may be multiple

sources and stand-by systems/generators/photovoltaic systems as well as auxiliary supplies

from other boards

If a removable or rack out circuit breaker or combined fuse switch is used it should, if

reasonably practicable, be racked out or removed then locked open and danger tagged

Securing the isolation

Locking the isolating switches where practicable or removing and tying back relevant

conductors to protect the persons carrying out the electrical work.

Tagging the switching points where possible to provide general information to people at

the workplace.

Testing to confirm the relevant circuits have been de-energised and any other relevant

conductors in the work area

Re-testing as necessary, for example, if the person carrying out the work temporarily leaves

the immediate area, checks and tests must be carried out on their return to ensure that the

electrical equipment being worked on is still isolated to safeguard against inadvertent

reconnection by another person.

4.4.2 The effectiveness of isolation procedures relies on:

Isolation points being readily available/accessible and being suitable for the type of

isolation (switching) being conducted.

The necessary hardware.

Having isolation procedures documented and accessible to electrical workers in the

workplace.

The provision of instruction, information and training of electrical workers involved with

the electrical equipment.

Appropriate supervision to ensure safe work procedures, including isolation procedures,

are followed.

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Safe isolation procedures (including the use of locks and tags) should be developed in consultation

with relevant workers. If the workers are represented by a health and safety representative, the

consultation must involve that representative.

4.4.3 Securing the isolation

A person conducting a business or undertaking must ensure that electrical equipment that has been

de-energised to allow electrical work to be carried out on it is not inadvertently re-energised while

the work is being carried out.

For work on low voltage electrical equipment or circuits, ensure that the correct point of isolation

is identified, an appropriate means of isolation is used and the supply cannot be inadvertently re-

energised while the work is carried out.

A fundamental principle is that the point of isolation should be under the control of the person who

is carrying out the work on the isolated conductors.

Tagging systems should also be used at the point(s) of isolation where possible for general

information.

The isolation should be secured by locking off and tagging the electrical equipment as follows.

Instruction, information, training and supervision

Appropriate instruction, information, training and supervision must be provided to ensure that

electrical equipment that has been de-energised to allow electrical work to be carried out is not

inadvertently re-energised. This includes appropriate instruction, information and training on

isolation proced..ures to everyone who may be affected at the workplace.

4.4.4 Locking off

Isolation points should be fitted with control mechanisms that prevent the electrical equipment

from being inadvertently re-energised. The control mechanism should require a deliberate action

to engage or disengage the device. It should be able to withstand conditions that could lead to the

isolation failing, for example vibration.

This may include switches with a built-in lock and lock-outs for switches, circuit breakers, fuses

and safety lock-out jaws (sometimes called ‘hasps’).

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All circuit breakers, switches and combined fuse switch units should be locked off to secure the

isolation where possible.

Alternative controls may include an additional component, for example a clip, screw, bolt or pin

that can be inserted to prevent a switch from being operated. These types of controls should be

used in conjunction with additional control measures, such as danger tags and permit systems.

If more than one person is working on the same de-energised electrical installation, individuals

should ensure their own personal lock is applied to the isolation point, otherwise the principles of

tagging apply (see below).

No-one should operate an isolator or knowingly use equipment where the isolator has a control

mechanism attached.

In situations where isolation points are accessible by other persons at the workplace ensure, so far

as is reasonably practicable, that the isolation method or system is not able to be inadvertently or

easily compromised.

4.4.5 Tagging systems

Danger tags involves using suitable warning or safety signs as well as locks or other controls to

secure the isolation. Where possible, a tag should be attached to normal locks at all points of

isolation used to de-energise electrical equipment from its electricity supply. A tag does not

perform the isolation function.

Danger tags are not required when using dedicated personal isolation locks.

Danger tags are used for the duration of the electrical work to warn persons at the workplace that;

the electrical equipment is isolated or out of service.

the electricity supply must not be switched back on or reconnected.

reconnecting electricity may endanger the life of the electrical worker(s) working on the

equipment.

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4.4.6 The danger tag should:

be durable and securely fixed to the isolator.

clearly state the warning, including any warning about specific hazards relating to the

isolation (for example, multiple points of supply).

be dated and signed by the worker or workers involved in carrying out the work or, where

appropriate, by the supervisor in charge of the workers.

be attached in a prominent position on each isolation point (i.e. the point or one of many

points used to isolate electrical parts) or device.

only be removed by the signatories to the tag. If unavailable and unable to return, measures

must be put in place to manage risks associated with removing the lock or tag (e.g. thorough

investigation to ensure all workers and others at the workplace are safe).

If the work is incomplete, for example at a change of shift, the last person removes their danger

tag or lock and replaces it with a warning tag e.g. out of service or caution. When work is resumed,

the person in charge of the work removes the warning tag (out of service or caution) and each

person then applies their danger tag and/or lock. When work is finally completed, each person

removes their danger tag and/or lock. Where a formal permit system is used, all reasonable steps

must be taken to ensure that the designated sign-on and tagging procedures are followed.

4.4.7 Out of service tags

Out of service or caution tags are used to identify electrical equipment that is not safe to use or fit

for purpose. The out of service or caution tag should:

be durable and securely attached.

clearly state the nature of the defect or reason why the electrical equipment is unsafe.

be attached on a prominent position on each isolation point.

only be removed by a competent person after fixing or rectifying the defect and making

the electrical equipment safe, or replacing with a danger tag in preparation to work on the

equipment.

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4.4.8 Restoring power

All reasonable steps must be taken to ensure that restoring electricity supply following isolation

does not pose risks to health and safety at the workplace. For example:

appropriately terminating all conductors.

carrying out appropriate testing on any new, altered or repaired electrical equipment, for

example tests for insulation resistance, earth continuity, polarity, correct connection and

function testing.

removing safeguards, including temporary bonds and short-circuiting devices.

notifying all workers working on the electrical equipment and other affected workers at the

workplace that electricity is to be restored.

taking precautions as appropriate to ensure that other electrical equipment is not

inadvertently energised.

carrying out a visual inspection to ensure that all tools, surplus material and waste has been

removed from the workplace.

When electricity is restored tests must be carried out to confirm that polarity is correct, actives are

switched .

4.4.9 Leaving unfinished work

If work is left unfinished, the workplace must be left in a safe state including, for example, by:

terminating any exposed conductors.

physically securing any exposed conductors or surrounding metal work.

tagging, taping off the electrical equipment and the workplace area.

informing affected persons at the workplace the work is not complete and advising of

potential hazards.

taking any necessary precautions to ensure that electrical equipment cannot become

inadvertently re-energised.

ensuring that the status of switchboards and electrical equipment are clearly and correctly

labelled

28

handing over adequate information to workers taking up the unfinished work to allow them

to continue the work safely.

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CHAPTER 5

RISK CONTROLS – ENERGISED ELECTRICAL WORK

5.1 Prohibition on Energised Electrical Work

A person conducting a business or undertaking carrying out electrical work must ensure the work

is not carried out on energised electrical equipment unless:

it is necessary in the interests of health and safety that the electrical work is carried out

while the equipment is energised (e.g. it may be necessary for life-saving equipment to

remain energised and operating while electrical work is carried out on the equipment)

it is necessary that the electrical equipment to be worked on is energised in order for the

work to be carried out properly.

it is necessary for the purposes of testing to ensure the equipment is de-energised.

there is no reasonable alternative means of carrying out the work

These requirements in relation to energised electrical work do not apply to work carried out by or

on behalf of electricity supply authorities on the electrical equipment, including line-associated

equipment, controlled or operated by the authority to transform, transmit or supply electricity.

These authorities may be covered by separate electrical safety requirements.

Energised electrical work is electrical work carried out in circumstances where the part of electrical

equipment being worked on is connected to electricity or ‘energised’.

Electrical work must not be carried out on electrical equipment while energised only because it is

merely more convenient for the electrical equipment to stay energised while the work is being

carried out.

Energised electrical work must not be carried out unless the safety risk to those persons directly

affected by a supply interruption is higher than the risk to the licensed or registered electrical

workers proposed to carry out the energised electrical work. Only in extremely rare circumstances

would it be possible to justify that it is not practicable to have a short break in supply. Most

electrical installations suffer no harm through unplanned interruptions of this kind to the network

supply. In some cases a short break may allow for the insertion (and removal) of insulated barriers.

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A Person conducting a business or undertaking requiring electrical work to be carried out may

provide operational reasons appearing to justify energised electrical work. Requiring electrical

work to be carried out while the equipment is energised when it could be avoided places an onerous

responsibility on the business or undertaking commissioning the work to minimize the risks.

Should an incident occur as a result of carrying out energised electrical work, the business or

undertaking commissioning the work is at risk of being found not to have provided a safe

workplace. This could contravene the primary duty of care under the WHS Act.

Energised electrical work is generally prohibited unless one or more of the exceptions under the

WHS Regulations applies and the work is carried out in accordance with the WHS Regulations.

5.2 Planning and Preparation

If electrical work is to be carried out on energised electrical equipment a person conducting a

business or undertaking must ensure before the work commences that:

a risk assessment is conducted by a competent person in relation to the proposed work and

recorded

the area where the electrical work is to be carried out is clear of obstructions so as to allow

for easy access and exit

the point at which the electrical equipment can be disconnected or isolated from its

electricity supply is:

clearly marked or labelled, and

cleared of obstructions so as to allow for easy access and exit by the worker who is to carry

out the electrical work or any other competent person, and

capable of being operated quickly

the person authorises the electrical work after consulting with the person with management

or control of the workplace.

Requirements relating to the point of supply under the third dot point above do not apply if the

work is to be carried out on the supply side of the main switch on the main switchboard for the

equipment and the point at which the equipment can be disconnected from its electricity supply is

not reasonably accessible from the work location.

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5.3 Risk Assessments

A risk assessment involves considering what could happen if someone is exposed to a hazard and

the likelihood of it happening. Risks associated with electrical work may arise from:

the properties of electricity, electricity is particularly hazardous because electrical currents

are not visible and do not have any smell or sound

how and where the electrical work is carried out. Electrical work may be carried out in

difficult conditions, including in wet weather conditions, confined spaces and in

atmospheres that present a risk to health and safety from fire or explosion.

the competence of the persons carrying out the electrical work.

If energised or ‘live’ electrical work is proposed to be carried out, a risk assessment must be

undertaken before the work starts and it must be carried out by a competent person and recorded.

5.4 Consultation Between Duty Holders

All persons conducting a business or undertaking at a workplace have a duty to manage electrical

risks at the workplace while electrical work is being carried out, not just those carrying out the

electrical work.

Electrical work will often be carried out at a place that is not under the management or control of

the person conducting the business or undertaking carrying out the electrical work. For example,

the place where work is carried out may be under the management or control of:

if the place is a permanent workplace—the person conducting a business or undertaking

from that workplace

if the place is a public place—the relevant local or state authority.

These persons will also have duties in relation to the health and safety of the electrical worker(s)

and other persons at the place where the electrical work is being carried out.

All duty holders must, so far as is reasonably practicable, consult, cooperate and coordinate

activities with each other to ensure compliance with their work health and safety duties. In addition

to the general duty to consult, the person conducting a business or undertaking carrying out the

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electrical work must ensure the electrical work is only authorised (among other things) after

consulting with the person with management or control of the workplace.

Consultation should ensure that all relevant persons are aware of any scheduled electrical work to

be carried out and also any relevant risks to health and safety arising from that work.

Arrangements should also be put in place to ensure, so far as is reasonably practicable, that all

persons at the place receive suitable and adequate information and instruction, for example about

the need to comply with warning or safety signs and stay out of any no go zones.

5.5 Residential Premises

Occupiers of residential premises (as a person at a workplace) must take reasonable care that their

acts or omissions do not adversely affect the health or safety of other persons, including that of

electrical workers at their premises.

Carrying out energised electrical work

A person conducting a business or undertaking must ensure that electrical work carried out on

energised electrical equipment is carried out:

by a competent person who has tools, testing equipment and PPE that are suitable for the

work, have been properly tested and are maintained in good working order

in accordance with a safe work method statement prepared for the work, and

subject to the exception explained below—with a safety observer present who is

competent:

to implement the control measures in an emergency

to rescue the worker who is carrying out the work if necessary, and

has been assessed in the previous 12 months as competent to rescue and resuscitate

a person.

The person must ensure, so far as is reasonably practicable, that the person who carries out the

electrical work uses the tools, testing equipment and PPE properly.

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Additionally:

workers carrying out the electrical work must have or be provided with suitable and

adequate information, instruction and training in:

planning and preparation requirements for the carrying out of energised electrical work

safe work procedures, particularly those documented in safe work method statements

proper use of the relevant tools, testing equipment and PPE

first aid facilities must be provided at the workplace and they must be readily accessible

emergency contact numbers should be made available at the workplace

fire fighting equipment that is suitable for electrical fires should be accessible

the person with management or control of the workplace must be consulted before the

electrical work is authorised

energised conductors should be insulated where necessary to prevent inadvertent contact

or flashovers

unauthorised persons should be prevented from entering the work area, for example

through the use of barriers and signage.

Many of these requirements require consultation, cooperation and coordination between multiple

duty holders at the workplace.

Safe work method statements prepared for energised electrical work must describe consultation

arrangements with the person with management or control of the workplace, including any

authorisation procedures and position descriptions.

5.6 Safe Work Method Statements

Safe work method statements document a process for identifying and controlling health and safety

hazards and risks. They may also incorporate a risk assessment.

Safe work method statements must be developed in consultation with relevant workers. If the

workers are represented by a health and safety representative, the consultation must involve that

representative.

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Safe work method statements must:

identify the electrical work.

specify the hazards associated with that electrical work and risks associated with those

hazards

describe the measures to be implemented to control the risks

describe how the risk control measures are to be implemented, monitored and reviewed,

and may include the risk assessment prepared for the relevant work.

Safe work method statements must be written in a way that makes them readily understandable by

the workers who are to use them.

A copy must be readily accessible to any worker who is to carry out the electrical work covered

by the statement. Safe work method statements must be kept up-to-date. They must, for example,

be revised if a decision is made to change relevant safe work procedures at the workplace.

5.7 Risks Associated With Electrical Work Control Measures

Isolation and access

Correctly isolating supply but not discharging residual energy e.g. a capacitive charge may

be present in power supplies, single-phase motors or high power factor fluorescent fittings.

Insulation and equipment failing or partially breaking down.

Earth connection failing to stop an electric shock in earthed conductive parts when step

and touch potentials exist.

Carrying out the task causes a person, something a person may be handling or something

a person is in contact with to intrude into minimum safe approach distances.

A power system conducting fault current or being subject to high inrush currents.

Instructions or markings on the parts being inadequate, incorrect or both.

Using equipment not designed for, or capable of, an operation e.g. opening a ‘no load –

bus tie’ under load conditions or relying on an open circuit breaker as an isolation point.

Another person energising circuits while a worker is working on them, or a vehicle hitting

a pole.

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Natural elements (i.e. lightning or wind) causing static charges, overhead mains to clash or

a high-voltage circuit to fall onto a low-voltage circuit.

The inter-core capacitive effects of long multi-phase cables.

Changes to wiring not being reflected in drawings i.e. the drawings are not ‘as built’ e.g. a

live control or supervision circuit being present though the drawing indicates otherwise.

If there has been an error in wiring, opening the isolator may not de-energise the

switchboard e.g. if incorrect connection (incorrect polarity) occurred in the service to an

installation, opening the main switch will open circuit the neutral rather than the active.

Intentionally disabling an interlock to perform a task e.g. opening the shutter of a ‘rackable’

circuit breaker test to prove de-energised in the orifice.

Inadvertently disabling an interlock while performing a task e.g. in a switchboard with an

integrated circuit breaker, isolator and earth switch, the operator accidentally moving the

isolator into the earthed position.

Poor direction and insufficient knowledge e.g. a worker is instructed to apply a set of earths

and short circuits at a Ring Main Unit (RMU). The worker correctly observes the isolator

is open, however they assume the earth switch can be closed because the isolator is open.

As most RMUs are configured so the earth switch earths the cable, not the busbar, it is

possible the worker would be earthing and short-circuiting a live circuit.

When applying a set of portable earths and short-circuits, accidental or inadvertent contact

is made with live parts. If this occurs, the worker is using a device that is conducting fault

current.

The threshold value (lowest level of indication or reading) of a test device causing a

misleading interpretation of a test to prove de-energised. Depending on the device used, an

indication that parts are not energised in a high-voltage situation does not mean that low-

voltage and direct current voltages are absent.

Application of earthing and short-circuiting devices that depend on a conductive path

through a fuse or circuit breaker that is not fit for purpose.

Ineffective connection to the general mass of the earth e.g. the electrode, grid or temporary

electrode that the earth and short circuits relies upon in a situation where a single phase

becomes energised.

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Application of the short circuit portion of portable earthing devices prior to the earth tail

being connected to the earth.

Arcing and splattering associated with the application of earths and short circuits, causing

a risk. The arcing or splattering may result from using the device in situations that range

from energised conductors to residual energy such as capacitance. If the parts are energised,

the worker can draw the arc from one phase to the other, causing a phase-to-phase fault.

A potential electric shock path existing once the earth tail is connected to earth. A worker

may touch another live part and the earthed connector at the same time, for example in a

Common Multiple Earthed Neutral (CMEN) area, even when working on high-voltage,

contact between the earthed connector and a low-voltage phase can cause an electric shock.

Working near sources of arcing, explosion or fires, Arcs, explosions and electrical faults can cause

burns. Workers should be protected from the effects of burns. Examples include: materials

providing a conductive path between sources of potential, for example uninsulated tools falling

across busbars.

abnormal conditions on circuits such as:

lightning striking mains

circuits of different voltages touching each other e.g. high-voltage contacting low-voltage

circuits

high voltage in the secondary circuit of a current transformer if an open circuit occurs when

current is flowing in the primary circuit.

abnormally high voltages when synchronising different supplies. For example, if the

waveforms are 180° out of phase, twice the peak-to-peak voltage may be imposed

voltage multiplication effects, including:

ferro-resonance where the capacitive and inductive components of underground cables and

transformers can significantly increase voltages when single-phasing occurs.

re-strike can occur if capacitors are energised, de-energised and re-energised in rapid

succession.

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leakage or electrical discharge causing insulation to be compromised, for example a

combination of a build-up of contaminants on insulators, wet weather or tracking through

air voids in pitch filled insulating chambers

failure of insulating mediums.

5.8 Working in Unsafe Atmospheres

After faults and fires, often in emergencies, electrical workers may be exposed to unsafe

atmospheres. Toxic gases and lack of oxygen can cause illness and death. General workplace

health and safety risk control measures should be used in these situations.

The method of extinguishing fires should be addressed. Typically, carbon dioxide or powder type

devices are used against electrical fires. Extinguishers including water, foam and wet chemical

should not be used as they significantly increase the risk of electric shock.

Modifying or repairing existing low-voltage electrical installations

Electrical drawings/tables not reflecting ‘as installed’ installations.

More than one source of supply or energised circuit may be available on the premises or at

the equipment.

The supply becoming energised during the work.

Automatic starting of machinery after supply is restored.

Managing metallic shavings ingress into conductive parts of equipment.

A conductor considered to be de-energised was found to be energised.

Old installations (where several modifications may have been made, circuits have not been

identified, or the insulation has deteriorated).

Voltages on disconnected conductors, particularly neutrals.

Installations where the MEN system is used, the rise in the earth potential due to a high

impedance return path to the distribution neutral.

Lack of information about isolation, sources of supply or the location of electrical

conductors.

Lack of clear safe access to locate electric cables (other hazards may be present such as

exposed conductors).

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Damage to conductors in metallic conduits where earthing continuity of the conduit has

not been maintained.

Equipment located in hazardous areas, which includes bolt-on or screw-on covers, can be

dangerous if opened without obtaining specialist advice.

Working alone on energised equipment.

Drilling into switchboards/electrical enclosures.

Contact with cables in walls, floors or roof spaces.

Contact with cables during excavation work or cutting/drilling concrete.

Exposure to asbestos material/switchboards.

Variable frequency devices.

Multiple circuits located within the one conduit.

Use of conductive/flammable cleaning solvents creating an explosive atmosphere.

5.9 Testing and Fault Finding Low-Voltage Equipment and Installations

Risks arise as it is difficult to find faults or malfunctions in electrical equipment when the circuits

are not energised or when the equipment is not operating, especially if feedback circuits or sensors

are involved. Risks can include:

electrical drawings/tables not reflecting ‘as installed’ installations

exposed energised terminals or conductors

terminals or conductors being energised under different conditions of operation of the

equipment

loose or disconnected test leads or wiring becoming energised

test equipment and leads bringing electrical hazards closer to the worker

test equipment inappropriate for the task (particularly test probes)

inadequate test points

inadvertent attempts to start machinery by other persons

incorrect or poorly maintained testing instruments

inadequate knowledge of equipment or causes of faults

lack of information about circuits or equipment

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equipment located in hazardous areas, which includes bolt-on or screw-on covers, can be

dangerous if opened without obtaining specialist advice

testing or fault finding alone on energised equipment

testing or fault finding in cramped or restricted work situations

rotating or moving machinery (crush hazards)

overriding of interlocks or forcing of control equipment

re-setting of protective devices in energised switchboards

electrical installations where unauthorised electrical work has been undertaken.

High fault currents – working, testing or fault finding energised

When working, testing or fault finding on energised electrical equipment, a fault current of up to

20 times the rated current of the supply transformer can flow for short duration during fault

conditions.

Arcs can have the energy to cause an explosion and/or melt metallic switchboard cubicles and

equipment. Arcs may cause severe burns to the skin and flash burns to the face and eyes. Inhaled

hot gases and molten particles can cause serious internal burns to the throat and lungs. Injury can

also occur through the impact from flying debris and dislodged components. Circuit protection

devices may not operate in such circumstances. Testing, fault finding or working on or near low

voltage equipment

Voltages between phases and between phases and neutral.

Voltages between phases and earth.

Voltages across open switch contacts, for example voltage across a light switch on an

incandescent lighting circuit or the voltage across a bus tie where one side is de-energised

Voltages on disconnected conductors (particularly neutrals).

Voltages from sources near the work being performs harmonics, for example 3rd harmonic

150 Hz in neutrals and earths where there is a large fluorescent light load and switch mode

power supplies

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5.10 Preventative Actions Checklist

INITIAL ASSESSMENT

Yes No

Can the work be undertaken while the electrical equipment is

de-energised?

If Yes, proceed to Part 2. If No, is it:

necessary in the interests of health and safety that the

electrical

work is carried out on the equipment while the equipment

is energised?

OR

necessary that the electrical equipment to be worked on is

energised in order for the work to be carried out properly?

OR

are there no reasonable alternative means of carrying

out the work?

If your answer to any of these is ‘yes’ proceed to Part 3 after

considering whether part of the installation or equipment may

be de-energised while the work is carried out.

If you cannot answer ‘yes’ to any of these proceed to Part 2—you

must work de-energised.

WORKED ON DE-ENERGISE Yes No

Do you have approved test instruments suitable for the task?

Have you checked that the test instruments are functioning correctly?

Have you isolated the supply e.g. by switching off?

Have you taken precautions to ensure that the supply remains

isolated

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Have you taken precautions to ensure that the supply remains

isolated by locking off and/or tagging, or disconnecting the load side

of the isolator and tying back disconnected conductors?

Have you conclusively tested that the equipment is

de-energised?

You must carry out the electrical work in accordance with

any safe work method statement that must be prepared

for the work.

PART 3: WORK ON OR NEAR ENERGISED EQUIPMENT Yes No

Has a risk assessment been conducted by a competent person which

identifies all electrical hazards and non-electrical hazards, both

actual

and potential?

Is the work area clear of obstructions to allow for easy access?

Is the isolation point clearly marked or labelled and capable of being

operated quickly?

Has the person with management or control of the workplace been

consulted about the proposed electrical work?

Do you have a safe work method statement for the task

at hand? This should state the control measures required

to eliminate or minimise the risks

Are you trained, competent and confident in applying the particular

procedures or techniques that are required for

the task?

Have you checked to ensure that your tools and accessories are

insulated and have been inspected and maintained to ensure they are

serviceable?

Is your test equipment appropriate to the task and functioning

correctly?

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Are you wearing the appropriate clothing and associated PPE for the

task e.g. safety helmet and boots, insulating gloves?

Do you have the appropriate insulating mats and sheeting?

Is a safety observer present?

Note: a safety observer is not required for electrical work if it only

involves testing and the risk assessment shows that there is no

serious

risk associated with the work.

Are the necessary first aid facilities provided and accessible and are

unauthorised persons prevented from entering the work area?

REMEMBER:

Do the work very carefully.

Follow the safe work procedures.

Assume all exposure conductors are energised.

Be aware of the voltage to the earth of all exposed

conductors.

Yes No

Have the installations/circuits/equipment been restored to

a safe and operable condition?

Have all tags and locking-off devices been removed?

5.11 Components Control Measures

5.11.1 Fuse

Normally, a fuse is a copper wiring with a set current fusion value. If the current exceeds the set

fusion value, the fuse will blow and the current is cut-off, thus preventing overloading. A fuse

interrupts excessive current (blows) so that further damage by overheating or fire is prevented.

Wiring regulations often define a maximum fuse current rating for particular circuits. Overcurrent

protection devices are essential in electrical systems to limit threats to human life and property

damage. The time and current operating characteristics of fuses are chosen to provide adequate

protection without needless interruption. Slow blow fuses are designed to allow harmless short

43

term currents over their rating while still interrupting a sustained overload. Fuses are manufactured

in a wide range of current and voltage ratings to protect wiring systems and electrical equipment.

Self-resetting fuses automatically restore the circuit after the overload has cleared, and are useful

in environments where a human replacing a blown fuse would be difficult or impossible, for

example in aerospace or nuclear applications.

Figure 2: a fuse

5.11.2 Circuit Breakers

All newer homes are protected by circuit breakers. Unlike a fuse that must be replaced when it

blows, a circuit breaker that has “tripped” can be mechanically reset to resume operations once the

problem has been resolved. Each circuit breaker contains a permanent metal strip that heats up and

bends when electricity moves through it. If a circuit shorts out or becomes overloaded, the metal

strip bends enough to “trip,” flipping a switch that immediately shuts off power to the circuit.

Circuit breakers also protect branch circuits, which can be sized for 120-volts or 240-volts.

Figure 3: Circuit Breaker

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5.11.3 Arc Fault Circuit Interrupters (AFCIS)

AFCIs are new protective devices that replace standard circuit breakers in the electric service

panel. AFCIs provide enhanced protection against additional fire hazards known as arc faults. An

arc fault is a dangerous electrical problem caused by damaged, overheated, or stressed electrical

wiring or devices. Without AFCIs, arc faults may be hidden from plain view until it is too late.

Figure 4 : Arc Fault Circuit Interrupters

5.11.4 Ground Fault Circuit Interrupters (GFCIs)

Since the 1970s, Ground Fault Circuit Interrupters (GFCIs) have saved thousands of lives and have

helped cut the number of home electrocutions in half. GFCIs are electrical safety devices that trip

electrical circuits when they detect ground faults or leakage currents. A person who becomes part

of a path for leakage current will be severely shocked or electrocuted. These outlets prevent deadly

shock by quickly shutting off power to the circuit if the electricity flowing into the circuit differs

by even a slight amount from that returning.

A GFCI should be used in any indoor or outdoor area where water may come into contact with

electrical products. The 2008 edition of the National Electrical Code currently requires that GFCIs

be used in all kitchens, bathrooms, garages, and outdoors.

GFCIs should be tested once a month to confirm that they are working properly.

45

Figure 5: Ground Fault Circuit Interrupters

The night light should go out when the test button is pushed. If the light does not go out, then the

GFCI may have been improperly wired or damaged and does not offer shock protection. In this

case, contact a licensed electrician to check the GFCI and correct the problem.

5.11.5 Earth Leakage Circuit Breaker

Current leakage protection is also called Residual Current Protection (RCD) or Earthing Fault

Current Protection. Earth leakage circuit breakers monitor the operation of the "neutral" or "live"

wires in the electrical circuit. During an imbalance in the electrical circuit, or when not all the

current flows to the electrical appliance through the "live" wire and returns through the "neutral"

wire, part of the current flows away (leaks) into other sources. The earth leakage circuit breaker

will immediately detect such an imbalance and cut-off the electrical source in 0.4 seconds. Rating

of the tripping current shall not exceed 30mA.

Figure 6 : Earth Leakage Circuit Breaker

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5.11.6 Insulation

One way to safeguard individuals from electrically energized wires and parts is through insulation.

An insulator is any material with high resistance to electric current.

Insulators-such as glass, mica, rubber, and plastic-are put on conductors to prevent shock, fires,

and short circuits. Before employees prepare to work with electric equipment, it is always a good

idea for them to check the insulation before making a connection to a power source to be sure there

are no exposed wires. The insulation of flexible cords, such as extension cords, is particularly

vulnerable to damage.

5.11.7 Extra-low voltage

Using electrical tools with an extra-low voltage of less than 50 V may minimise injury in case of

electric shock. When extra-low voltage is used, an earthing connection may not be required.

5.11.8 Guarding

Live parts of electric equipment operating at 50 volts or more must be guarded against accidental

contact. Guarding of live parts may be accomplished by:

location in a room, vault, or similar enclosure accessible only to qualified persons;

use of permanent, substantial partitions or screens to exclude unqualified persons;

location on a suitable balcony, gallery, or platform elevated and arranged to exclude

unqualified persons; or

elevation of 8 feet (2.44 meters) or more above the floor.

Entrances to rooms and other guarded locations containing exposed live parts must be marked with

conspicuous warning signs forbidding unqualified persons to enter. Indoor electric wiring more

than 600 volts and that is open to unqualified persons must be made with metal-enclosed

equipment or enclosed in a vault or area controlled by a lock. In addition, equipment must be

marked with appropriate caution signs.

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Figure 7: Guarding System

5.12 Safe Work Practices

Employees and others working with electric equipment need to use safe work practices. These

include: de-energizing electric equipment before inspecting or making repairs, using electric tools

that are in good repair, using good judgment when working near energized lines, and using

appropriate protective equipment.

5.13 Training

To ensure that they use safe work practices, employees must be aware of the electrical hazards to

which they will be exposed. Employees must be trained in safety-related work practices as well as

any other procedures necessary for safety from electrical hazards.

De-energizing Electrical Equipment. The accidental or unexpected sudden starting of electrical

equipment can cause severe injury or death. Before ANY inspections or repairs are made -- even

on the so-called low-voltage circuits-the current must be turned off at the switch box and the switch

padlocked in the OFF position. At the same time, the switch or controls of the machine or other

equipment being locked out of service must be securely tagged to show which equipment or

circuits are being worked on.

Maintenance employees should be qualified electricians who have been well instructed in lockout

procedures. No two locks should be alike; each key should fit only one lock, and only one key

should be issued to each maintenance employee. If more than one employee is repairing a piece of

equipment, each should lock out the switch with his or her own lock and never permit anyone else

48

to remove it. The maintenance worker should at all times be certain that he or she is not exposing

other employees to danger.

5.14 Overhead Lines

If work is to be performed near overhead power lines, the lines must be de-energized and grounded

by the owner or operator of the lines, or other protective measures must be provided before work

is started. Protective measures (such as guarding or insulating the lines) must be designed to

prevent employees from contacting the lines.

Unqualified employees and mechanical equipment must stay at least 10 feet (3.05 meters) away

from overhead power lines. If the voltage is more than 50,000 volts, the clearance must be

increased by 4 inches (10 centimeters) for each additional 10,000 volts.

When mechanical equipment is being operated near overhead lines, employees standing on the

ground may not contact the equipment unless it is located so that the required clearance cannot be

violated even at the maximum reach of the equipment.

Protective Equipment. Employees whose occupations require them to work directly with

electricity must use the personal protective equipment required for the jobs they perform. This

equipment may consist of rubber insulating gloves, hoods, sleeves, matting, blankets, line hose,

and industrial protective helmets.

Tools. To maximize his or her own safety, an employee should always use tools that work properly.

Tools must be inspected before use, and those found questionable, removed from service and

properly tagged. Tools and other equipment should be regularly maintained. Inadequate

maintenance can cause equipment to deteriorate, resulting in an unsafe condition.

Tools that are used by employees to handle energized conductors must be designed and constructed

to withstand the voltages and stresses to which they are exposed.

Good Judgment. Perhaps the single most successful defense against electrical accidents is the

continuous exercising of good judgment or common sense. All employees should be thoroughly

familiar with the safety procedures for their particular jobs. When work is performed on electrical

equipment, for example, some basic procedures are:

1. Have the equipment de-energized.

49

2. Ensure that the equipment remains de-energized by using some type of lockout and tag

procedure.

3. Use insulating protective equipment.

4. Keep a safe distance from energized parts.

50

CHAPTER 6

EARTHING

6.1 Definition of Earthing

In electrical engineering, ground or earth can refer to the reference point in an electrical circuit

from which voltages are measured, a common return path for electric current, or a direct physical

connection to the Earth. A typical earthing electrode consisting of a conductive rod driven into the

ground.

6.2 Reasons for Earthing

Electrical circuits may be connected to ground (earth) for several reasons. In mains powered

equipment, exposed metal parts are connected to ground to prevent user contact with dangerous

voltage if electrical insulation fails. Connections to ground limit the build-up of static electricity

when handling flammable products or electrostatic-sensitive devices. In some telegraph and power

transmission circuits, the earth itself can be used as one conductor of the circuit, saving the cost of

installing a separate return conductor.

For measurement purposes, the Earth serves as a (reasonably) constant potential reference against

which other potentials can be measured. An electrical ground system should have an appropriate

current-carrying capability to serve as an adequate zero-voltage reference level. In electronic

circuit theory, a "ground" is usually idealized as an infinite source or sink for charge, which can

absorb an unlimited amount of current without changing its potential. Where a real ground

connection has a significant resistance, the approximation of zero potential is no longer valid. Stray

voltages or earth potential rise effects will occur, which may create noise in signals or if large

enough will produce an electric shock hazard.

6.3 Earthing system

Electrical power distribution systems are often connected to ground to limit the voltage that can

appear on distribution circuits. A distribution system insulated from ground may attain a high

potential due to transient voltages caused by arcing, static electricity, or accidental contact with

higher potential circuits. A ground connection of the system dissipates such potentials and limits

the rise in voltage of the grounded system.

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Figure 8: Earthing system

Equipment earthing conductors provide an electrical connection between non-current-carrying

metallic parts of equipment and the earth. According to the U.S. National Electrical Code (NEC),

the reason for doing this is to limit the voltage imposed by lightning, line surges, and contact with

higher voltage lines. The equipment earthing conductor is usually also used as the equipment

bonding conductor.

6.4 How Earthing System Work

Equipment bonding conductors provide a low impedance path between non-current-carrying

metallic parts of equipment and one of the conductors of that electrical system's source, so that if

a part becomes energized for any reason, such as a frayed or damaged conductor, a short circuit

will occur and operate a circuit breaker or fuse to disconnect the faulted circuit. Note that the earth

itself has no role in this fault-clearing process since current must return to its source, not the earth

as is sometimes believed (Kirchhoff's circuit laws). By bonding (interconnecting) all exposed non-

current carrying metal objects together, they should remain near the same potential thus reducing

the chance of a shock. This is especially important in bathrooms where one may be in contact with

several different metallic systems such as supply and drain pipes and appliance frames. The

equipment bonding conductor is usually also used as the equipment earthing conductor.

Permanently installed electrical equipment usually also has permanently connected grounding

conductors. Portable electrical devices with metal cases may have them connected to earth ground

by a pin in the interconnecting plug (Domestic AC power plugs and sockets). The size of power

ground conductors is usually regulated by local or national wiring regulations.

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6.5 Earthing of a Power Distribution System

Distribution power systems may be solidly grounded, with one circuit conductor directly

connected to an earth grounding electrode system. Alternatively, some amount of electrical

impedance may be connected between the distribution system and ground, to limit the current that

can flow to earth. The impedance may be a resistor, or an inductor (coil). In a high-impedance

grounded system, the fault current is limited to a few amperes (exact values depend on the voltage

class of the system); a low-impedance grounded system will permit several hundred amperes to

flow on a fault. A large solidly-grounded distribution system may have thousands of amperes of

ground fault current.

In a polyphase, AC system, an artificial neutral grounding system may be used. Although no phase

conductor is directly connected to ground, a specially constructed transformer (a "zig zag"

transformer) blocks the power frequency current from flowing to earth, but allows any leakage or

transient current to flow to ground.

6.6 Effect of Ungrounded Systems

Where the danger of electric shock is high, special ungrounded power systems may be used to

minimize possible leakage current to ground. Examples of such installations include patient care

areas in hospitals, where medical equipment is directly connected to a patient and must not permit

any power-line current to pass into the patient's body. Medical systems include monitoring devices

to warn of any increase of leakage current. On wet construction sites or in shipyards, isolation

transformers may be provided so that a fault in a power tool or its cable does not expose users to

shock hazard.

Circuits used to feed sensitive audio/video production equipment or measurement instruments may

be fed from an isolated ungrounded technical power system to limit the injection of noise from the

power system.

6.7 Lightning Protection Systems

Lightning protection systems are designed to mitigate the effects of lightning through connection

to extensive grounding systems that provide a large surface area connection to earth. The large

area is required to dissipate the high current of a lightning strike without damaging the system

53

conductors by excess heat. Since lightning strikes are pulses of energy with very high frequency

components, grounding systems for lighting protection tend to use short straight runs of conductors

to reduce the self-inductance and skin effect. Busbars are used for ground conductors in high-

current circuits.

6.8 Electrical Bonding

Strictly speaking, the terms grounding or earthing are meant to refer to an electrical connection to

ground/earth. Bonding is the practice of intentionally electrically connecting metallic items not

designed to carry electricity. This brings all the bonded items to the same electrical potential as a

protection from electrical shock. The bonded items can then be connected to ground to bring them

to earth potential.

6.9 Earthing Mat

In an electrical substation a ground (earth) mat is a mesh of conductive material installed at places

where a person would stand to operate a switch or other apparatus; it is bonded to the local

supporting metal structure and to the handle of the switchgear, so that the operator will not be

exposed to a high differential voltage due to a fault in the substation. In the vicinity of electrostatic

sensitive devices, a ground mat is used to ground static electricity generated by people and moving

equipment.

6.10 Isolation (Disconnector)

It means physically disconnected from all possible sources of supply. Generally every AC power

line transformer acts as an isolation transformer, and every step up or down has the potential to

form an isolated circuit. However, this isolation would prevent failed devices from blowing fuses

when shorted to their ground conductor. The isolation that could be created by each transformer is

defeated by always having one leg of the transformers grounded, on both sides of the input and

output transformer coils. Power lines also typically ground one specific wire at every pole, to

ensure current equalization from pole to pole if a short to ground is occurring.

Electrical engineering, a disconnector, disconnect switch or isolator switch is used to ensure that

an electrical circuit is completely de-energised for service or maintenance. Such switches are often

found in electrical distribution and industrial applications, where machinery must have its source

54

of driving power removed for adjustment or repair. High-voltage isolation switches are used in

electrical substations to allow isolation of apparatus such as circuit breakers, transformers, and

transmission lines, for maintenance. The disconnector is usually not intended for normal control

of the circuit, but only for safety isolation. Disconnector can be operated either manually or

automatically (motorized disconnector).

Unlike load break switches and circuit breakers, disconnectors lack a mechanism for suppression

of electric arc, which occurs when conductors carrying high currents are electrically interrupted.

Thus, they are off-load devices, intended to be opened only after current has been interrupted by

some other control device. Safety regulations of the utility must prevent any attempt to open the

disconnector while it supplies a circuit. Standards in some countries for safety may require either

local motor isolators or lockable overloads (which can be padlocked).

Disconnectors have provisions for a padlock so that inadvertent operation is not possible (lockout-

tagout). In high-voltage or complex systems, these padlocks may be part of a trapped-key interlock

system to ensure proper sequence of operation. In some designs, the isolator switch has the

additional ability to earth the isolated circuit thereby providing additional safety. Such an

arrangement would apply to circuits which inter-connect power distribution systems where both

ends of the circuit need to be isolated.

Figure 9 : Disconnector

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CHAPTER 7

HOUSE KEEPING

Figure 10 : House Keeping

7.1 Concept of House Keeping

Workmen are frequently injured, by stumbling, stepping on, or bumping into tools, material and

other objects left lying around, or by objects falling from above. To ensure good housekeeping

following precautions should be observed:

Walks, stairways, fire escapes and all other passageways shall be kept clear of all

obstructions.

Tools and materials should not be placed where they may cause tripping or stumbling

hazards or where they may fall and strike anyone below.

Puddles of oil and water create slipping hazards and should be cleaned up promptly.

Nails in boards, such as those removed from scaffolds, forms and packing boxes, constitute

hazards and should be removed. The boards should be carefully stacked or stored.

Dirty and oily waste rags should be deposited in approved containers and disposed off as

soon as practicable to avoid fire hazard.

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Broken light bulbs, glass metal and scrap and other sharp objects should be dumped in

places or containers provided specially for them.

Discarded fluorescent and other gas filled tubes shall be disposed off safely.

Places where persons work or pass in emergencies, shall be provided during time of use

with adequate lighting (natural / artificial / or both) for operations or special type of work

performed.

General lighting shall be of a uniform level widely distributed.

In big installations / offices emergency lighting shall be provided.

Adequate ventilation shall be provided in work places by natural / artificial means.

7.2 Electrical Safety for Buildings

All electrical installations for Bureau owned, operated, or leased buildings including, but not

limited to, gage stations, marina docks, cabins, and shelters must:

Be installed, repaired, and/or maintained by a licensed electrician.

Have a disconnect that will allow the electricity to be de-energized and that can be locked

out.

Be grounded or employees protected by ground-fault circuit interrupters (GFCIs). GFCIs

will not protect equipment.

If subjected to wet conditions, be protected from water; employees must be protected by

ground-fault circuit interrupters.

Have an arc lash hazard assessment and be labeled with the required precautions for live

electrical work.

7.3 Equipment

Normal use of electrical equipment causes wear and tear that results in insulation breaks, short

circuits, and exposed wires. If there is no ground-fault protection, it can cause a ground fault that

sends current through an employee’s body.

Use ground-fault circuit interrupters (GFCIs) on all 120-volt, single-phase, 15- and 20-

ampere receptacles on all field equipment.

Use double-insulated tools and equipment, distinctively marked.

57

Visually inspect all electrical equipment before use. Remove from service any equipment

with frayed cords, missing ground prongs, cracked tool casings, or other hazards.

Use only equipment that is listed and labeled by a nationally recognized testing laboratory

for the intended use.

7.4 Extension Cords

Normal wear on cords can loosen or expose wires. Cords that are not 3-wire type, not designed for

hard usage, or that have been modified increase your risk of contacting electrical current.

Do not modify cords or use them incorrectly.

Use factory-assembled cord sets and only extension cords that are 3-wire type.

Use only cords, connection devices, and fittings that are equipped with strain relief.

Remove cords from receptacles by pulling on the plugs, not the cords.

Use of extension cords (flexible cords) for permanent installation of appliances and

equipment is prohibited.

Replace extension cords that are damaged so individual wires can be seen through the

protective sheathing. Do not repair.

If an extension cord insulation is cut, it is better to cut the damaged section out and add a

new plug than to try and repair the insulation. Never repair insulation using electrical tape,

which does not have equivalent insulation and it is easily damaged.

7.5 Power Lines

Overhead and buried power lines are especially hazardous because they carry extremely high

voltage. Fatal electrocution is the main risk, but burns and falls are also hazards.

Look for overhead power lines and buried power line indicators.

Stay at least 10 feet away from overhead power lines and assume they are energized.

Use nonconductive wood or fiberglass ladders when working near power lines.

De-energize and ground lines when working near them. Call the electrical utility to do

this.

Call the electrical utility for work that it is responsible for, such as tree trimming.

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7.6 Safety do’s and don’t

s/n Do’s Don’t

1 Before replacing a lamp or handling a

fan, make sure that the supply is

switched off.

Do not connect single pole switch or fuse in

a neutral circuit, but always connect in the

live or phase wire.

2. Place Safety Tagging or other warning

boards on main switch before

commencing work

Do not close any switch, unless you are

familiar with the circuit which it controls

and know the reason for its

being open

3. Before working on any circuit or

apparatus,make sure that the

controlling switches are open and

locked.

Do not touch or tamper with any electrical

gear or conductor, unless you have made

sure that it is dead

and earthed. High voltage apparatus may

give leakage shock or flash over even

without touching

4. Always treat circuit as live until you

have proved them to be dead, the

insulation of the conductor may be

defective.

Do not work on live circuit without the

orders of the authorized person. Make

certain that all safety precautions have been

taken

5. Cultivate the habit or turning your

face away whenever the flash or an arc

may

occur.

Do not disconnect earthing connection or

render it ineffective of the safety gadgets

installed on mains and apparatus.

6. Guard against arcs as well as high

voltage; remember that burns from arc

are very severe.

Do not tamper with the meter board and cut-

outs,

unless you are authorized to do so

7. See that all the splices and

connections are securely made.

Do not expose your eyes toan electrical arc.

Painful

59

. injury may result even with short exposure.

8. Use extreme care when breaking an

inductive circuit as dangerously high

voltage is likely to result.

Do not close or open a switch slowly or

hesitatingly. Do it quickly and positively

9. Thoroughly discharge to earth all

cables before working on cores.

Do not place any part of yourbody in circuit

either to ground or across the terminal when

making a connection or doing operation

10. Test rubber gloves periodically.

Do not touch an electrical circuit when your

hands are wet, bleeding from a cut or have

an abrasion

11 Place rubber mats in front of

electrical switchboard

Do not work on energized circuit without

taking extra precautions, such as the use of

rubber gloves. Do not use metal case flash

light around apparatus which is energized.

12 Preach and practice safety at all the

time. Good work can be spoiled by an

accident.

Do not wear loose clothing, metal watch

straps, bangles or finger rings while

working on appliances. Do not hang clothes

and such other things on electric fittings. Do

not touch the circuit with bare fingers or

hand or other makeshift devices to

determine whether or not it is live.

13 Work deliberately and carefully.

Haste causes many accidents. Be sure

of what you are doing.

Do not work on pole or any elevated

position if there is a live part on it, without

the safety belt and rubber gloves and unless

60

the authorized person stand on the ground

nearby to direct operation and give warning.

14 Always obey the safety instructions

given by the person in-charge.

Do not use a ladder without a lashing rope,

otherwise the ladder should be held firmly

by another person. Do not remove Safety

Tags or other signs or interface with safety

barriers or go beyond them

15 Always report immediately to the

person in-charge or to any other

proper authority of any dangerous

condition or a practice, which you

may observe.

Do not bring naked light near battery.

Smoking in the battery room is prohibited.

Do not allow visitors and un-authorized

person to touch or handle electrical

apparatus or come within the danger zone of

high voltage apparatus.

16 Ensure that all portable appliances are

provided with 3 pin plug and socket

connections. Also the metal work of

the apparatus is effectively earthed.

Do not use a lamp in a metal holder fixed to

the end of a loose flexible wire as a portable

hand lamp. Do not disconnect a plug by

pulling the flexible cable

or when the switch is on

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CHAPTER 8

PERMIT TO WORK

8.1 Definition of Permit to Work

The Permit-to Work procedure provides a formal control system aimed at the prevention of

accidents and damage to property where foreseeable hazardous work is carried out.

The Permit-to-Work consists of documents which:

Details the work to be done.

Details the precautions to take.

Identifies all the foreseeable hazards.

States the control measures to be implemented.

Cancellation.

List other permits in operation.

Permits themselves do not make a job free from risks, they rely upon effective control and co-

ordination in order that hazards are identified and risks are suitably assessed.

The Health and Safety Executive identify the following requirements of a Permit-to-Work;

Type of Permit – i.e. Electrical, Asbestos etc.

Unique Permit Number.

Location of work.

Details of the work to be carried out.

Identification of hazards.

Precautions required.

Personal Protective Equipment required.

Authorisation to commence work.

Any extension of permit time.

Handback.

Cancellation.

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8.2 Conditions for a Permit

The company will expect Permits-to-Work to be issued to ether high and low voltage work in the

following situations;

A. Working in confined spaces.

B. Work in control and switching.

C. cable jointing work

D. Working with Asbestos

E. working on overhead lines.

F. Work on underground cable.

G. work on high voltage electrical equipment.

8.3 Competent Persons

The use of Competent Persons is a prime requirement of the Permit-to Work system. Although

Competency has never been defined in either case or statute law, the Health and Safety at Work

Regulations define a person as being Competent when that person;

“Has sufficient training and experience or knowledge as to enable him to assist in securing

compliance, on the part of the employer, with the necessary safety legislation and maintenance

procedures”.

It is expected that those persons designated as Competent to have had:

Valid certificated training, where this is deemed necessary, including an element of health and

safety appreciation, relevant to the Permit to be issued.

Experience of the work to be carried out.

Knowledge of the Permit-to-Work procedures.

8.4 Monitoring the Work

As far as is reasonably practicable, the Competent Person shall be responsible for monitoring the

work at regular intervals, to ensure that the operatives are adhering to the conditions of the permit.

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8.5 Completed Work

When the work has been completed the Competent Person will inspect the site to ensure that:

The works have ceased.

All tools and equipment have been removed.

The work area has been left in a satisfactory and safe condition.

When the Competent Person is satisfied that these conditions have been met the permit will be

cancelled and copies filed with the contract documents (if appropriate) and in the Permit file. These

permits should be kept for 12 months.

8.6 Out of Working Hours

Whenever possible, work that requires a Permit-to-Work should be carried out only during normal

working hours. However, there will be occasions when this is not possible and the Competent

Person must ensure that he is available to monitor contractor or staff compliance throughout the

duration of the permit irrespective of when it takes place.

Details of PPE

Method statement of work to be carried out.

Monitoring of the atmosphere.

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Chapter 9

PERMIT TO WORK 2 (ELECTRICAL SYSTEMS)

9.1 High Voltage

The Permit-to-Work system for High Voltage applies to contractors and staff who may have need

to enter any High Voltage substations. It DOES NOT allow for switching of the H.V. circuits or

for maintenance of the equipment, this can only be carried out by authorised SEEBOARD staff.

The duration of the Permit-to-Work will be no longer than a maximum of one day. For

work that may take longer than the one day, a separate permit should be issued for each

day.

Requirements to be met to enable access to the substation;

The Competent Person must ensure that access to the substation will not in any way effect

the H.V. switchgear or controls.

The Competent Person must stay at the substation if access is required for 1 hour or less.

For periods of more than 1 hour the Competent Person must be available on the premises

and be within immediate communication with those in the substation.

Only those staff named on the Permit-to-Work will be allowed in the substation.

The substation must not be left unlocked and unattended.

9.2 Low Voltage

Low voltage is regarded as a voltage exceeding 50v AC or 120v DC between conductors or earth,

but not exceeding1000v AC or 1500v DC between conductors or 600v AC or 900v DC between

any conductor and earth.

Requirements to be met when working on low voltage electrical installations;

The Competent Person must ensure that before disconnection or isolation of any

distribution board or circuit that feeds a distribution board, the electrical equipment

effected has been identified and if appropriate the users notified.

That staff and contractors are aware of the need to lock-off all isolation switches in the

OFF position.

65

The Competent Person should issue a Permit-to-Work when any of the following work is

carried out on low voltage electrical installations;

Switching off any switch fuse, distribution board, or mains circuit board that may affect

the University’s IT systems, the safety of any person, or the electrical supply to fire alarm

systems.

Work on remote and automatically controlled low voltage switchgear.

The duration of the Permit-to-Work will be issued for a maximum of 5 working days and

should be location specific.

66

Chapter 10

ELECTRICAL EMERGENCY RESPONSE TECHNIQUES

10.1 Electrical Rescue Techniques

Approaching the accident.

Never rush into an accident situation.

Call rescue telephone lines as soon as possible.

Get the aid of trained electrical personnel if possible.

Approach the accident scene cautiously.

Examining the scene:

Visually examine victims to determine if they are in contact with energized

conductors. Metal surfaces, objects near the victim or the earth itself may be energized. You may

become a victim if you touch an energized victim or conductive surface. Do not touch the victim

or conductive surfaces while they are energized. De-energize electrical circuits if at all possible.

10.2 Methods to De-energize:

An extension or power cord probably powers portable electrical equipment.

Unplug portable electrical equipment to remove power.

Open a disconnecting device or circuit breaker to de-energize fixed electrical equipment.

10.3 Hazards and Solutions:

Be alert for hazards such as stored energy, heated surfaces and fire.

If you can’t de-energize the power source use extreme care:

Ensure that your hands and feet are dry.

Wear protective equipment such as low voltage gloves and overshoes if available.

Stand on a clean dry surface.

Use nonconductive material to remove a victim from the conductor.

10.4 High Voltage Rescue:

Special training is required for rescues if high voltage is present.

67

Protective equipment such as high voltage gloves and overshoes must be worn.

Special insulated tools should be used

10.5 Insulated Tools:

Insulated tools, with high voltage ratings, are a lifesaver!

Use devices such as hot sticks or shotgun sticks to remove a victim from energized

conductors.

In some cases, nonconductive rope or cord may be used to remove a victim from a

conductor.

10.6 Rescuing the Victim:

Stand on a dry rubber blanket or other insulating material if possible.

Do not touch the victim or conductive material near the victim until the power is off.

Once power is off, examine the victim to determine if they should be moved.

Give “First Aid.”

10.7 First Aid:

A victim may require Cardio-Pulmonary Resuscitation (CPR).

If the victim is breathing and has a heartbeat, give first aid for injuries and treat for shock.

Ensure the victim gets medical care as soon as possible.

Provide medical personnel with information on voltage level, shock duration & entry/exit

points.

The treating/attending physician must have detailed specific information to properly

diagnose and care for the victim. The physician must determine whether the victim should

be sent to a “Trauma or Burn

10.8 Center:

Stay with the victim until help arrives.

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CHAPTER 11

CONCLUSION

The health and safety programs have been elaborated in order to prevent the risk of work related

incidents and to facilitate safety when working in electrical environment especially at distribution

level. Health and safety laws requires the employers to look after the health, safety and welfare of

their employees. They also must consider who could be affected with their work, their clients,

contractors and visitors to their premises. Employers also have a duty identify, assess and control

safety risks and must write down the significant findings of their risk assessment if they have five

or more employees.

Providing a safe working environment need not be a difficult or time consuming exercise,

particularly if in a low risk environment. The most important thing is to make safety part of our

business culture driven by a commitment from the top of the organization. Benefit of working

safely include fewer accident, reduce insurance premiums, a better motivated workforce and peace

of mind.

Employees who ever involve in Electrical works both at construction and operational level, they

have to know their right, safety and safety and health and what the company care and responsible

on them. All the regulations and conditions at site are important to everybody who is at the site

because they are always at risk. The company has to ensure the works under its control and carried

out in such a way to minimize the risk to health and safety for employees and any other person

who could be affected. If the aforementioned control measures are fully implemented, a safe

working environment will be guarantee.

We must always remember it is our right to live, invariably it is our right to work in a safe

environment, through cooperative efforts between employers and employees can learn to identify

and eliminate or control electrical hazards, because safety is everyone’s business.

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REFERENCES

1. Charles K. Alexander, Matthew N. O Sadiku, (2004) "Fundamentals of Electric Circuits

"2nd Edition, McGraw, Hill publishing.

2. Institute of Safety Professionals of Nigeria (2012) "General Health Safety Environment

Training Manual" Nigeria.

3. Institute of Safety Professionals of Nigeria, (2012) "Contractor Employee Health Safety

Environment Training Manual Level 3", Nigeria.

4. Electrical Safety Foundation International (2008 ) " Electrical safety Workbook",

5. Occupation Safety & Health Council (2006) "Note on Electrical Safety ".

6. Occupational Safety and Health Administration (2006)," Fire Service Features of

Buildings and Fire Protection Systems ", United State of America.

7. Code of Practice (2012) " Managing Electrical Risks in Workplace " Australia,

8. John J. Shea, "Identifying Causes for Certain Types of Electrically Initiated Fires in

Residential Circuits" Electrical Eaton Corporation, Pittsburgh.

9. North Delhi Power Limited, (2007) "Electrical Safety Manual" (A Tata Power and Delhi

Government Joint Venture),India.

10. Workplace Safety & Environmental Protection (2012), "Electrical Safety Guide For

Non- Electrical Workers ".

11. Frederick F. Franklin, (1991) "A survey of Electrical Fire".

12. International Association of Oil and Gas Procedures(1993)"Guideline on Permit to

work "

13. Nagrath I.J, Kothari D.P,(2006)"Power System Engineering",Tata McGraw-Hill

Publishing Company Limited, India.

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