09 electrical safety sos (14!08!2013)

7/29/2019 09 Electrical Safety SOS (14!08!2013)

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WELCOME

ELECTRICAL SAFETY AT WORK

Safety theme for September 2013

Compiled by M. Zahid Siddiqui
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Electrical current is the flow of electrons through a conductor.

A conductor is a material that allows electrons to flow through it.

An insulator resists the flow of electrons.

Resistance opposes electron flow.

Fundamentals of Electricity



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Fundamentals of Electricity continued.


Current Flows in a Loop or Circuit

Circuits are AC (alternatingcurrent) or DC (direct current).

Current is usually AC.

AC current has five parts:

(1) Electrical source

(2) HOT wire to the tool.

(3) The tool itself

(4) NEUTRAL wire returnselectricity from the tool

(5) GROUND


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Fundamentals of Electricity continued.


How Shocks Occur

Current travels in closed circuits through

conductors (water, metal, the human

body).

Shock occurs when the body becomes apart of the circuit.

Current enters at one point & leaves at

another.


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Shocks Occur in Three Ways

Contact with both

conductors

Contact with oneconductor and ground

With a tool: contact with

hot metal part and

ground (1), (2) & (3)


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Take Electricity Seriously

Electricity is the second leading cause of death in construction.

Electrocutions make up 12% of construction fatalities annually.

Over 30,000 non-fatal shocks occur each year.

Over 600 deaths occur annually due to electrocution.

It doesn't take a lot of electricity to kill you. The amount of current

needed to light an ordinary 60-watt light bulb is five times what can kill a

person. Thus, all electrical equipment on construction sites is potentially

deadly.



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Take Electricity Seriously continued.


Severity of the Shock depends on:

Amount of current

Determined by voltage and resistance toflow

Path through the body

Duration of flow through the body

Other factors such as general health and

individual differences. LOW VOLTAGE DOES NOT MEAN

LOW HAZARD!


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Leading Causes of Electrical Accidents

Drilling and cutting through cables

Using defective tools, cables and equipment

Failure to maintain clearance distance of 10 feet

Failure to de-energize circuits and follow Lock out/Tag out procedures

Failure to guard live parts from accidental worker contact

Unqualified employees working with electricity

Improper installation/use of temporary electrical systems and equipment

By-passing electrical protective devices

Not using GFCI (ground fault circuit interrupters) devices

Missing ground prongs on extension cords



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Use of Flexible Cords

Are more vulnerable than fixed wiring.

Should not be used if recognized wiring

methods can be used instead.

Flexible cords can be damaged by: Aging

Door or window edges

Staples or fastenings

Abrasion from adjacent materials

Activities in the area Improper use of flexible cords can cause

shocks, burns or fire.


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Meaning of Hazard

Hazard means:

any potential or actual threat to the wellbeing of people, machinery or

environment

Electrical hazard safety means:

taking precautions to identify and control electrical hazards



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Electrical Hazard Awareness

It is essential to know about it Because failing to take the necessary

precautions can lead to:

injury or death

fire or property damage

Electrical hazards exist in almost every workplace. Common causes

of electrocution are:

making contact with overhead wires

undertaking maintenance on live equipment

working with damaged electrical equipment, such as extension

leads, plugs and sockets

using equipment affected by rain or water ingress



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Difference between incident and emergency:

An incident is something that has already happened that may need

attending too quickly, whereas an emergency is something that will need tohave attention because it may make the situation less harmful


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How do you respond to electrical incidents?

What should you do in an electrical emergency?

For low voltage electricity >50 V AC and 110 V DC

remove the source of electricity supply

commence CPR if trained call the emergency number on site

For high voltage electricity >1000 V

call the emergency number for your site

dont go near the casualty

dont touch the casualty or try to free them with anything



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Your respond to electrical incident

If you come across a person receiving an electric shock:

if possible, disconnect the electrical supply (switch?)

assess the situation never put yourself at risk

take precautions to protect yourself and anyone else in the vicinity

apply the first aid principles (e.g. DRSABCD)

assess the injuries and move the casualty to

a safe area if required

administer first aid if trained

seek urgent medical attention




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You could be the victim if you:

Dont follow proper procedures aroundelectricity

Use electrical equipment improperly

Use faulty electrical equipment

Following are the types of injuries due to

electric shock:

Falls

Electric shock; Electric burn;

Fires of electrical origin;

Electric arcing;

Explosions initiated or

caused by electricity.




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Effects of Current Flow

Levels of effect of current on human body

More than 3 milliamps (mA): painful shock

More than 10 mA: muscle contraction More than 20 mA: considered severe shock



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Effectsof Current Flow


Levels of effect of current on human body continued

More than 30 mA: lung paralysis - usually temporary

More than 50 mA: possible ventricular fibrillation (usuallyfatal)

100 mA to 4 amps: certain ventricular fibrillation (fatal)

Over 4 amps: heart paralysis; severe burns



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Effects of Current Flow continued.



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All electrical incidents must be reported

Electricity is invisible this in itself makes it

dangerous

It has great potential to seriously injure or kill

The company has a duty of care to its employees

and contractors

Everyone is exposed to electrical hazards, not just

electricians

Report all electrical shocks and near misses



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Protect yourself and your colleagues from electricity

Dont wear metal objects

Turn power off

Wear appropriate clothing Dont touch live parts

Dont install or repair

electrical equipment

Use qualified personnel

Clean and dry leads and

plugs before use

Use PPE



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Some more safety measures

Heed warning signs

Use the right equipment

Study the operation manual

Take care of extension leads

Use only approved extension lamps

Dont pull on leads

Use residual current devices RCDs

Use the proper fuses and circuit breakers



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Regular safety inspections

are a part of YOUR job...

Electrical equipment should be

checked each time before use fordefects

If not tagged or the tag is out of date

then report it and place it out of service



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Controlling Electrical Hazards

Employers must follow the OSHA Electrical Standards (Subpart

K)

Electrical installation

Subpart K includes four proactive methods:

Electrical Isolation

Equipment Grounding

Circuit Interruption

Safe Work Practices


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Power line to be approached safely


Up to and including to 33 kV

2.3 m when passing underneath and 3 m when

passing to the side

Above 33 kV

4 m when passing underneath and 6 m when

passing to the side



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Controlling Electrical HazardsCircuit Protective Devices

Circuit Breakers and Fuses

Only protect the building, equipment, and tools from heat build-

up!Never depend on circuit breakers or fuses to prevent shocks!

Ground Fault Circuit Interrupter (GFCI)

It is one of the device which will protect the worker from shockand electrocution!


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Circuit Protective DevicesResidual Current Device (RCD):

An RCD is a safety device that

disconnects a circuit when it detects animbalance of the electric current. Itworks on the principle that the electricityflowing into a circuit must be equal tothe current flowing out of a circuit. Whena person receives a shock, it means

some current is diverted through thebody directly to earth.


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Circuit Protective DevicesResidual Current Device (RCD) continued..

If the RCD detects an imbalance in the electrical current, indicating aleakage to earth, it immediately cuts the electricity supply to preventelectrocution.

An RCD cannot detect all types of faults, for example if a person receivesa shock between the active and neutral conductors. However, thesecircumstances are rare and the vast majority of incidents occur betweenthe active conductor and earth, which is protected by an RCD.

If a person comes in contact with a live electrical conductor, electricityflows through their body, causing an electric shock. Effects can vary froma tingling sensation or muscular pain to breathing difficulties, burns andheart failure.


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Circuit Protective Devices

Residual Current Device (RCD): continued..

RCDs are extremely sensitive, disconnecting within 10 to 50milliseconds of detecting a leakage current. This is usually 30

milliamps for domestic residences but may be lower in other locationssuch as hospitals. This stops the flow of electricity through someonesbody to earth. Importantly, this response time is much faster than thecritical section of the cardiac cycle and therefore significantly reducesthe risk of death or serious injury.

RCDs also protect against fire caused by faults in appliances, toolsand wiring. If these faults go undetected they could cause a fire orpersonal injury. RCDs provide a means of early fault detection.


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Residual Current Device (RCD): continued.

RCDs are required to be fitted at the meter box (main switchboard) ordistribution board for the residence.

Various brands of RCDs are available; however they can all beidentified by the test button located on the front of the device.

If you press the test button, or the RCD has detected an imbalance,

the on/off switch will jump to the off position.

Residual-current device is a generic term covering both RCCBs andRCBOs


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Power Line Corridor


MSI Regulation 5.28 defines a power line corridor as the area under

any overhead power line that has not been properly isolated, and 10

metres either side of the power line.

It is essential that these areas are respected. They are there for

the safety of everyone

Do not store equipment, machinery, buildings or structures in

power line corridors

Do not construct, fabricate or maintain structures, buildings,

machinery or equipment in power line corridors



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First obtain permission to dig


Be aware of the potential hazard from buried electrical cables for the

following activities:

excavation

drilling

trenching

levelling

digging

driving of stakes or pegs

Do not commence excavation work near buried cables unless a

permit has been issued by an authorised person

Do you know what precautionary measures need to be taken?



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The key messages are

The risk of electric shock from correctly installed and

maintained power sources is negligible, provided that sensible

precautions are taken by the operator and correct work

procedures are followed

Ensure that the right person is carrying out electrical work

licensed versus competent

Electricity is essential but, improperly used, it can be DEADLY!



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References 29 CFR 1926.400; Subpart K

National Electric Code (NEC)

AD EHSMS RF Version 2.0 February 2012

CoP 15.0 Electrical Safety


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End of the presentation


09 electrical safety sos (14!08!2013)

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