The issues of electrical

hazards at site

and steps to prevent

Group Member: Ng Huoy Miin

Hoi Wei Han

Lim Zi Shan1

Contents

1. Basic Concepts.2. Hazard Recognition.3. Effects of Electricity on Human Body.4. Electrical Hazard Protection. 5. Work Practices.

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Basic Concepts

Electrical hazard :

● A dangerous condition where a worker could make an electrical contact with energized equipment or a conductor from which the person may sustain an injury from shock.

The law requires safe work practices

● Under Occupational Health and Safety Act

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Why should we be concerned about electrical hazards?

● Electricity has long been recognized as a serious workplace hazard.

● Exposing the employees to electric shock, electrocution, burns, fires, and explosions.

● In 1999, for example, 278 workers died from electrocutions at work ,almost 5 percent of all on-the-job fatalities that year (the Bureau of Labor Statistics.)

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Electricity accidents result from :

1. Unsafe equipment or installation.

1. Unsafe environment.

1. Unsafe work practices.

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What affects the flow of electricity?● Electricity flows more easily through some materials than others.

❖ Conductors:

➔ The substances such as metals.

➔ Generally offer very little resistance to the flow of electric current .

➔ A common but perhaps overlooked conductor is the surface or subsurface of the earth.

➔ Even air, normally an insulator, can also become a conductor,

as occurs during an arc or lightning stroke.

❖ Insulators:

➔ Glass, plastic, porcelain, clay, pottery, dry wood, and similar substances

➔ Generally slow or stop the flow of electricity6

HOW DOES WATER AFFECT THE FLOW OF ELECTRICITY?

● Pure water is a poor conductor.

● But small amounts of impurities in water like salt, acid, solvents, or other materials can turn water itself and substances that generally act as insulators into conductors or better conductors.

● The same is true of human skin.

● Dry skin has a fairly high resistance to electric current.

● But when skin is moist or wet, it acts as a conductor.

● Working with electricity in a damp or wet environment .

● Needs to exercise extra caution to prevent electrical hazards.

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The following is a list of a common electrical hazards found on construction sites:

❏ Improper grounding.❏ Exposed electrical parts.❏ Inadequate wiring.❏ Damaged Insulation.❏ Overloaded Circuits.❏ Damaged tools and equipments.❏ Wet conditions.❏ Overhead Power Lines.

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Improper grounding

➔ Improper grounding of circuitry and equipment.

➔ Grounding of the metal components of the electrical wiring system such as conduit, ceiling light fixtures, switch plates and so on at 0 volts.

➔ Plugging of metal components into circuits which is grounded improperly will cause it becomes energized.

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Improper Grounding

➔Unwanted voltage will not be safely eliminated.

➔Leakage of current to the ground.

➔Removal of the ground pin.

➔Removing of the ground pin removes a vital safety feature.

➔Electroshocked will occur!

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Exposed electrical parts

➔ Exposed wires or terminals are hazardous.

➔ Report these conditions to your supervisor.

➔ The missing circuit breakers of the electrical panels.

➔ Using of panel which the wires are exposed.

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➔ All the openings must be enclosed.

➔ The outer insulation of electrical cords must be in perfect condition.

➔ The incontact of temporary lighting system with potential shocks and broken bulbs.

Exposed electrical parts

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Inadequate wiring.

➔Using improperly rated extension cords.

➔The power tools being used is improperly rated extension cord.

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Inadequate wiring.

DIFFERENT TYPES OF WIRES WITH THEIR ELECTRICAL CURRENT RATING

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Overhead power lines.

➔Lack of concern of overhead power lines on construction site.

➔Storing of equipments or materials under overhead power lines.

➔Not maintaining a distance of at least 10’ between equipment and tools and overhead power lines.

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Overhead power lines.

➔Shocks and electrocutions occur where physical barriers are not in place to prevent contact with the wires.

➔Examples of equipment that can contact power lines : Crane, Ladder, Scaffold, Backhoe and so on.

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Overhead power lines

➔Not maintaining a safe distances between scaffolding and overhead power lines.

➔Overhead power lines are very dangerous.

➔Never attempt to contact an overhead power line.

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Damaged insulation.

➔ Inadequate or defective insulation is a hazard.

➔No prevention to conductors by insulation from contacting with each other or us.

➔Repairing the damaged cord with tape.

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Damaged insulation.

➔Using tools or extension cords with damaged insulation.

➔Hanging of extension cords from nails or sharp objects.

➔Running the extension cords through doors or windows.

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Overloaded circuits.

➔ Overloaded circuits can cause fires.

➔ Improper circuit breakers are used.

➔ Overloading an outlet.

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Overloaded circuits.

➔ Using power strips or surge protectors on construction sites.

➔ Should use a 3-way extension with a ground fault circuit interrupter (GFCI) instead.

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Wet conditions.➔ Wet conditions are hazardous.

➔ Damaged insulation will increase the hazard in wet location.

➔Using tools in wet locations.

➔Water increases the risk of electric shock.

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Damaged tools and equipment.

➔Double insulated tools are labeled.

➔It will be marked “Double Insulated”.

➔It will have the following symbol:

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Effects of Electricity on Human Body

Three major types of electrical injuries

1. Electrocution

1. Electrical Shock

1. Burns

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WHAT causes shocks?

Electricity travels in closed circuits normally through a conductor.

A person’s body sometimes may become an efficient

conductor of electricity, and mistakenly becomes part of the

electric circuit,

which can cause electric shock.

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➔ electricity flows between parts of the body

➔ through the body to a ground or the earth

Shocks occur when a person's body completes the

current path with:

➔ both wires of an electric circuit

➔ one wire of an energized circuit

and the ground;

➔ a metal part that accidentally

becomes energized due,

- to a break in its insulation; or

- another " conductor" that is

carrying a current.

When a person receives a shock,

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What is the Danger of Static Electricity?

1. when friction causes a high level of static electricity to build up at a specific spot on an object.

2. handling plastic pipes and materials

3. during normal operation of rubberized drive

4. machine belts found in many worksites.

● build up on the surface of an object under the right conditions

- can discharge to a person, causing a shock.

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✓ static electricity can potentially discharge

✓when sufficient amounts of flammable or combustible substances are located nearby and cause an explosion.

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What effects do shocks have on the body?

An electric shock can result in anything

1. from a slight tingling sensation

2. to immediate cardiac arrest.

The severity depends on the following:

1. the amount of current flowing through the body,

2. the current's path through the body,

3. the length of time the body remains in the circuit

4. the current's frequency.

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Burns

Burns are the most common shock-related injury.

An electrical accident can result in :

Arc burn Thermal BurnElectrical Burn

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Electrical burns1. are among the most serious burns 2. require immediate medical attention.3. They occur when electric current flows through tissues or bone,4. generating heat that causes tissue damage.

Arc or flash burns 1. result from high temperatures 2. caused by an electric arc or explosion near the body. 3. These burns should be treated promptly.

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Thermal contact burns1. are caused when the skin touches hot surfaces of overheated electric

conductors, conduits, or other energized equipment. 2. can be caused when clothing catches on fire,3. as may occur when an electric arc is produced.

In addition to burns and shock,electricity poses other dangers1. arcs that result from short circuits can cause injury or start a fire. 2. Extremely high-energy arcs can damage equipment,3. causing fragmented metal to fly in all directions. 4. Even low-energy arcs can cause violent explosions in atmospheres that

contain flammable gases, vapors, or combust

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What should you do if someone “freezes” to a live electrical contact?

Act quickly, and remember to protect yourself as well from electrocution or shock.

Shut off the current immediately

If this is not possible,

Use any non-conducting materials and safely push or pull the person away from the contact

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Step to prevent

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Protection against electrical hazards

GroundingGuarding

Personal Protective Equipments

Insulation

Circuit Protection Devices Safety Practices

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1. Insulation

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What Protection does Insulation Provide?

Insulators :

1. Glass, mica, rubber, or plastic used to coat metals and other conductors

- prevent shock, fires, and short circuits.

1. must be suitable for the voltage used and conditions such as temperature and other environmental factors (eg. moisture, oil, gasoline, corrosive fumes, or other substances ) that could cause the insulator to fail.

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Types of Insulation● Basic Insulation

- The insulation applied to live parts to provide

basic protection against electric shock.

● Supplementary Insulation

- An independent insulation, applied in addition to

basic insulation

- to ensure protection against electric shock in the

event of failure of the basic insulation.

● Double Insulation

- Insulation comprising of both basic and

supplementary insulation.

● Reinforced Insulation

- A single insulation system applied to live parts,

- provides a degree of protection against electric

shock equivalent to double insulation.

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How do you identify different types of insulation?

1. Before connecting electrical equipment to a power

source, it's a good idea to check the insulation for any

exposed wires for possible defects.

2. Insulation covering flexible cords such as extension

cords is particularly vulnerable to damage.

3. It also specifies that the insulation used should be

suitable for the voltage and conditions.

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2.Guarding

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What is Guarding?

Recommended locations are a room, vault, or similar enclosure;

a balcony, gallery, or elevated platform; a site elevated 8 feet

(2.44 meters) or more above the floor. Sturdy, permanent screens

also can serve as effective guards.

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It involves locating or enclosing electric equipment

tomake sure people don't accidentally come into

contact with its live parts.

Effective guarding requires equipment with exposed parts operating at 50 volts

or more to be placed where it is accessible only to authorized people

qualified to work with it.

What Protection does It Offer?

Signs may contain the word " Danger," " Warning," or " Caution," to alerts people to the hazard and

gives an instruction, such as " Danger/High Voltage/Keep Out."

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Conspicuous signs must be posted at the entrances to electrical rooms and

similarly guarded locations to alert people to the electrical hazard and to forbid entry to unauthorized people.

3. Grounding

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Grounding

a tool or electrical system means intentionally creating a low-

resistance path that connects to the earth.

This prevents the buildup of voltages that could cause an

electrical accident.

A secondary protective measure that provides protect

against electric shock. It does not guarantee that you

won't get a shock, be injured or killed by an electrical current.

However, it does substantially reduce the risks.

What Protection does It Offer?● to protect machines, tools, and insulation

against damage.

● One wire, called the " neutral" or " grounded"

conductor, is grounded.

● In an ordinary low-voltage circuit, the white or

gray wire is grounded at the generator or

transformer and at the building's service

entrance.

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● An equipment ground helps protect

the equipment operator.

● furnishes a second path for the current

to pass through from the tool or

machine to the ground.

● This additional ground safeguards the

operator if a malfunction causes the

tool's metal frame to become

energized.

● activate the circuit protection devices.

4.Circuit protection devices

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circuit protection devices

● Protects worker from overcurrent

● Short circuits by automatically shutting off the electricity

Well-known examples of these devices are

Fuses and Circuit breakers

Ground-fault circuit interrupters

Arc-fault circuit interrupters

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Fuses and circuit breakers

How do they work:

1. open or break the circuit automatically

- when too much current flows through them.

1. When that happens

- fuses melt and circuit breakers trip the circuit open.

➢ to protect conductors and equipment.

➢ prevent wires and other components from overheating

➢ open the circuit when there is a risk of a ground fault.48

Ground-fault circuit interrupters

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Ground-fault circuit interrupters

➔ are used in

➔ These devices interrupt the flow of electricity within as little as 1/40 of a second

- prevent electrocution.

➔ compare the amount of current going into electric equipment

the amount of current returning from it

Circuit conductors

Wet location Construction Site High Risk Area

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Ground-fault circuit interrupters

➔OSHA requires the use of GFCIs on all construction sites.

➔is a fast-acting circuit breaker.

➔It senses small imbalances in the circuit caused by current leakage to ground.

➔ If the difference exceeds 5 milliamperes，

- the device automatically shuts off the electric power.

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Arc-fault circuit interrupters➔ Design to distinguish between normal and dangerous arcing conditions

➔ Trips during an arc fault-(power discharge between two conductors)

- Avoiding the high current that cause fires and sparking

➔ Provide protection from the effects of arc-faults

- By recognizing characteristics unique

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5.Personal Protective

Equipment

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Personal Protective equipment

Foot protection

1. Footwear will be marked “Electric Hazards” - If it’s approved for electrical work

1. Footwear must be kept dry- even if it is marked “Electric Hazards”

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Head ProtectioN

1. Hard hat(insulated non-conductive)2.Class B &E3.Always wear your hat 4.Do not store anything in the top of your hat

while wearing it

Hand ProtectioN1. Rubber insulating gloves2. Classified by the level of voltage and protection 3. Should always be worn over rubber insulating

gloves 4. To provide the mechanical protection needed

against cuts, abrasions, and punctures.55

Personal protective equipment

1. Use, store and maintain in a safe, reliable condition

1. Wear nonconductive head protection- Due to not contact with exposed energized parts

1. Wear protective equipment for the face and eyes- From electric arcs or flashes ,flying objects- Resulting from electrical explosion

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Electrical Personal protective equipment with any of the following defects may not be used:

● An embedded foreign object

● Any other defect that damages theinsulating properties

● Holes, tears, punctures, or cuts are presents

● Texture changes- Swelling, softening, hardening, or

becoming sticky or inelastic

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Role of tools

Help protect workers against electric hazards.

1. It's important to maintain tools regularly

- prevents them from becoming dangerous.

Check each tool before using it.

1. If you find a defect, immediately remove it from service

2. tag it so no one will use it until it has been repaired or replaced.

Handle energized conductors

1. check to make sure it is designed and constructed

- withstand the voltages and stresses to which it has been exposed.

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6.Work practices

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Basic procedures to follow

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1.Deenergize The Equipment

2.Lockout & Tag Procedures

3.Maintain a safe distance from energized parts.

Ensure that the equipment remains deenergized use insulating protective equipment

Lock out/ Tag-out

1. Workers must ensure electricity is off and “locked-out” - before work is performed.

1. The switch must be tagged.

1. The tag lets others know why the switch is off.

1. Locks and tags are warning signs.

1. Must be trained in lock-out/ tag-out procedure.

Protect you from the dangers of

● the accidental

● unexpected startup of electrical equipment .

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Only qualified electricians

- who have been trained in safe lockout procedures

- To maintain electrical equipment.

Each key should fit just one lock.

- one individual lock and key should be issued to each maintenance worker

Only authorized worker

- Lockout and tag the equipment.

- Get permitted to remove it.

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Lock out/ Tag-out

Special training of employees need

● Familiar with the safety procedures for their particular jobs.

● Good judgment and common sense

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Thank You

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References ● http://www.dosh.gov.my/index.php/en/component/content/article/35

2-osh-info/accident-case/955-accident-case

● http://slideplayer.com/slide/5667899/

● https://www.osha.gov/Publications/3075.html

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