Electrical

Safety By GSG

What is the definition

of a shock absorber?

A careless electrician.

Recall Basics of Electricity

1. Voltage

2. Amperage (Current)

3. Resistance

4. Circuit

Series

Parallel

What is "voltage"?

Voltage is a measure of the electrical force that

seems to push the current along.

The symbol for voltage is "V".

What is "voltage"?

Think of voltage as a lot of water

stored in a high water tank.

Because the water tank is high,

the water will have more force

behind it as it flows down the

water pipe.

This is why they put water tanks

up high! If the same tank was

placed at ground level, the water

pressure would not be as great.

What is “Amperage"?

Amperage is the unit used to measure the amount of

electrical current.

Amperage is often referred to as "current" by

electrical workers and engineers.

The symbol for amperage is "I".

Let's go back to the water tank.

If diameter of the pipe coming from

the water tank is large, a lot of

water (amperage) will flow through

the pipe.

If the pipe's diameter is small, a

smaller amount will of water flow.

If you need a lot of current to

operate the equipment, you'll need

large wires to run the current.

What is "amperage"?

What is “Resistance"?

Resistance is the unit (ohms)

used to measure the opposition to

the flow of electrical current.

It's that simple. In an electrical

circuit, components are usually

sources of resistance.

Any component that heats up due

to electrical current is a source of

resistance.

The symbol for resistance is "R".

What is a "circuit"?

A circuit is the complete

path for the flow of

current.

Electrical current may

flow through a circuit in a

series or parallel path.

What's a "series" circuit?

For example, water from high in the mountains may flow down

one stream (series) into a river that flows into the ocean.

What is a Parallel Circuit ?

Ex: The water flowing from a water falls on a hill will flow through

many different water branches (parallel) before it reaches the ocean.

Common

Mistakes at

Construction Sites

Common Mistakes in Construction sites

Common Mistakes in Construction sites

Common Mistakes in Construction sites

Common Mistakes in Construction sites

Common Mistakes in Construction sites

Common Mistakes in Construction sites

Common Mistakes in Construction sites

Common Mistakes in Construction sites

Common Mistakes in Construction sites

Common Mistakes in Construction sites

Common Mistakes in Construction sites

Common Mistakes in Construction sites

Types of

Electrical

Injuries

What kills – Voltage or Current ?

A common phrase heard in reference to electrical safety

goes something like this:

"It's not Voltage that kills, it’s Current!"

While there is an element of truth to this, there's more to

understand about shock hazard than this simple adage.

If voltage presented no danger, no one would ever print

and display signs saying:

“ DANGER - HIGH VOLTAGE”

How a Electrical shock occur ?

The principle that "current kills" is essentially correct. It is

electric current that burns tissue, freezes muscles, and

fibrillates hearts.

However, electric current doesn't just occur on its own; there

must be voltage available to motivate electrons to flow through

a victim.

A person's body also provide resistance to current, which must

be taken into account.

Obviously, the more voltage available to cause electrons to

flow, the easier they will flow through any given amount of

resistance. Hence, the danger of high voltage.

Hazards of Electricity

Shock

Arc

Blast

Effects of Electricity on the

Human Body

The four major types of electrical injuries are:

Direct

Electrocution

Electrical Shock

Burns

Indirect

Falls

Electrocution Vs Electrical Shock

‘Electrocuted’ and

‘Electrical Shock’ aren’t

always interchangeable.

‘Electrocuted’ can only be

used when an electrical

shock results in death.

If death does not occur,

the term ‘shocked’ should

be used.

Electric Shock

The electric shock is caused by a current passing

through the body.

The lethality of an electric shock is dependent on:

Current (the higher the current, the more likely it is lethal);

Duration (the longer the duration, the more likely it is lethal);

Voltage (the higher the voltage, the more likely it is lethal);

Pathway (if current flows through the heart muscle it is

more likely to be lethal).

Severity of Electrical Shock

The severity of injury

from electrical shock

depends on the amount

of electrical current and

the length of time the

current passes through

the body.

Electrical Shock

Touching a live wire

and an electrical

ground will cause a

shock.

Touching two live wires

of different voltages

will cause electrical

shock.

Electrical Shock

Electric shock is the passing of electric current through the

body.

The electrical current may

Prevent you from releasing your grip from a live

conductor.

Throw you into contact with a higher voltage conductor.

Cause you to lose your balance and fall.

Cause severe internal and external burns.

Kill you.

Electrical Injuries

The most common shock-related, nonfatal

injury is a burn.

Burns caused by electricity may be of three types:

Electrical burns,

Arc burns, and

Thermal contact burns.

Electrical Burns

An electrical burn is a burn

that results from electricity

passing through the body

causing rapid injury.

For a burn to be classified as

electrical, electricity must be

the direct cause.

Arc Flash An arc flash is a release of energy

caused by an electric arc. The flash

causes an explosive expansion of

air and metal.

The blast produces

A dangerous pressure wave

A dangerous sound wave

Extreme heat & Extreme light.

Arc Flash Temperatures as high as

35,000 F have been reached

in arc-blasts.

These dangers can result in

blast injuries, lung injuries,

ruptured eardrums, shrapnel

wounds, severe burns, and

blindness and can also result

in death.

Thermal Contact Burns

Thermal contact burns can

occur when electricity ignites

combustible material.

Thermal contact burns occur

when skin comes in contact

with overheated electric

equipment, or when clothing is

ignited in an electrical incident.

What route avoids your heart?

Right hand to left hand

Right hand to right foot

Right hand to left foot

Left hand to right foot

Left hand to left foot

Always use your right hand when working with live

power- and keep your left hand in your pocket!

What is Electrical Hazard?

An electrical hazard can be defined as:

A dangerous condition where a worker could make

electrical contact with energized equipment or a

conductor, and from which the person may sustain an

injury from shock; and/or,

There is potential for the worker to receive an arc flash

burn, thermal burn, or blast injury due to the electrical

contact.

Protection Against Electrical Hazards

Most electrical accidents result from one or more of the

following three factors:

Unsafe equipment or installation,

Unsafe environment,

Unsafe work practices.

Some ways to prevent these accidents are through the

use of insulation, guarding, grounding, electrical

protective devices, and safe work practices.

The Electrical Safety Model

What Must Be Done to Be Safe?

To make sure all employees are safe before, during

and after electrical work is performed, electrical

workers should follow the three-step process.

Electrical Safety Model:

1. Recognize hazards

2. Evaluate risk

3. Control hazards

How do your recognize hazards?

The first step toward protecting yourself is recognizing the many

hazards you face on the job. To do this, you must know which

situations can place you in danger. Some examples to recognize

hazards.

Inadequate wiring.

Exposed electrical parts.

Overhead power lines.

Electrical systems and tools

that are not grounded or

double-insulated.

Damaged power tools and

equipment .

Using the wrong PPE & Wrong

Power Tool.

Overloaded circuits.

Wires with bad .

Evaluating the Risks

After you recognize a hazard, your next step is to evaluate your

risk from the hazard. The closer you work to the "danger zone,"

the more likely you'll be exposed to the electrical hazard.

Wet conditions combined with other hazards also increase your

risk. You will need to make decisions about the nature of

hazards in order to evaluate your risk and do the right thing to

remain safe.

Another factor increasing your risk of injury is working around

combinations of hazards.

Evaluating the Risks (Contd..)

There may be important clues that electrical

hazards exist.

For example, if a GFCI keeps tripping while you are using a power

tool, that's a clue that there is a problem. A GFCI that trips indicates

there is current leakage from the circuit.

Don't keep resetting the GFCI and continue to work. You must

evaluate the "clue" and decide what action should be taken to control

the hazard.

A cable, fuse box, or junction box that feels warm may indicate too

much current in the circuits.

Evaluating the Risks (Contd..)

Some examples of evaluating the Risks.

Tripped circuit breakers.

Blown fuses.

An electrical tool, wire, or connection that feels warm.

A burning odor of electrical tools, cables, switches etc;

Damaged insulation.

Worn, frayed, or damaged insulation.

Any of these conditions, or "clues," tells you something

important: There is a risk of fire and electrical shock. The

equipment or tools involved must be avoided or rectified.

Control the Hazards

How Do You Control Hazards?

In order to control hazards, you must first create a safe

work environment, then work in a safe manner.

Generally, it is best to remove the hazards altogether

and create an environment that is truly safe.

Use as many safeguards as possible. If one fails,

another may protect you from injury or death.

Earthing & Grounding

Earth is used for the safety of the human body in

fault conditions while Grounding (As neutral earth) is

used for the protection of equipment.

Earthing is a preventive measure while Grounding is

just a return path.

Earthing is accomplished through bonding of a metallic

system to earth. It is normally achieved by inserting

ground rods or other electrodes deep inside earth.

Grounding means connecting the live part to the

earth (for example neutral of power transformer).

Electrical Protection

Installation of Circuit

Breakers & GFCI:

Circuit Breaker is

provided to protect

equipment, where as

GFCI (Ground Fault

Circuit Interrupter) is

provided to protect the

people.

Provide Double Earthing

Provide double Earthing is

required for welding

machine & electrical tools:

Double earthing gives low

resistance and also if any one

earth is out of order, second

will do the required work of

earthing the equipment.

De-energize circuits

Treat all conductors as if they are energized until they are

locked out and tagged.

Always test a circuit to make sure it is de-energised

before working on it.

(Lock-Out / Tag-Out) LOTO

Lockout/Tag-out is an essential

safety procedure that protects

workers from injury while

working on or near electrical

circuits and equipment.

Lock-out involves applying a

physical lock to the power

source(s) of circuits and

equipment after they have been

shut off and de-energized.

Provide proper enclosures

Prevent exposure to live electrical parts by isolating them.

Use correct size of cables

Prevent overloaded wiring by using the right size and type of wire.

Use Proper testing appliances Use approved portable meters and leads, not

improvised test lamps.

Close unused openings

Unused openings

in panels, cabinets,

boxes and fittings

must be effectively

closed.

Take proper precautions while working near

overhead power lines.

Best Safety Practice:

Survey the site for overhead

power lines.

Never get closer than 10 feet

to an overhead power line!

If work beneath live OH power

lines cannot be avoided,

barriers, and warning notices

should be provided.

Safety precautions during Welding

Connect electrical equipment

and work piece correctly.

Use the correct cable size.

Make sure all electrical

connections are tight, clean,

and dry.

Insulate yourself from work

piece and ground.

Remove metal jewelry.

Use proper PPE.

Other General Factors

Ensure that the locations of all buried electrical cables are

marked before work begins on any excavation.

You can prevent electrical shocks in two ways; de-

energizing the circuit prior to work or using safety

equipment on the energized circuit.

Ensure all rotating machinery components are protected

with proper guards. (Like chains, belts, wheels, fans etc).

Do not work in wet conditions.

Do not attempt to carry out repair works by yourself even if

it is of minor nature.

Summary

Electrical accidents don't happen without cause.

Sometimes it's equipment failure; Other times, it's operator

failure.

Electrical accidents are often fatal. No device that will

provide 100% protection.

Regardless, properly using required safety equipment

might reduce the seriousness of electrical shocks.

Take the necessary time to properly plan a job, it may help

avoid later delays caused by an accident.

Working with electricity can be dangerous. However,

electricity can be safe if properly respected.