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ELECTRIC SHOCK 06/21/22

Electric shock

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Page 1: Electric shock

ELECTRIC SHOCK

05/02/23

Page 2: Electric shock

Student Name:Jariwala Harekrishna H.

Department: Civil (A)

Pen No:150430106037

Guided By:Tejas G. Misrty.

05/02/23

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Contents:How shock occursPreventing electric hazardsOhm’s law of electricityEffects of electrical shock on human bodyHow it happens

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How Shock Occurs

• 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 • The path of the current through the body• The length of time the body is in the circuit.

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Other factors that may affect the severity Of shock are the: • Frequency of the current;

• Phase of the heart cycle when shock occurs

• General health of the person.

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• A difference of less than 100 mA exists between a current that is barely perceptible andone that can kill.

• Muscular contraction caused by stimulation may not allow the victim to free himself or herself from the circuit, and the increased duration of exposure increases the dangers to the shock victim.

• For example, a current of 100 mA for 3 seconds is equivalent to a current of 900 mA applied for0.03 seconds in causing ventricular fibrillation.

• LOW VOLTAGE DOES NOT IMPLY LOW HAZARD

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• A severe shock can cause considerably more damage to the body than is visible.

• For example, a person may suffer internalhemorrhages and destruction of tissues, nerves, and muscles.

• In addition, shock is often only the beginning in a chain of events.

• The final injury may well be from a fall, cuts, burns, or broken bones.

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How Electricity Hurts PeopleHow Electricity Hurts People

Current Impact on People1 mA no sensation1-3 mA sensation, no pain3-15 mA pain, most people can get away15-30 mA pain, half of people freeze30-75 mA pain, breathing difficult, asphyxiation75-200 mA possible ventricular fibrillation200-300 mA certain ventricular fibrillation300+ mA severe burns, heart stops

CurrentCurrent Impact on PeopleImpact on People1 mA 1 mA no sensationno sensation11--3 mA 3 mA sensation, no painsensation, no pain33--15 mA15 mA pain, most people can get awaypain, most people can get away1515--30 mA30 mA pain, half of people freezepain, half of people freeze3030--75 mA75 mA pain, breathing difficult, asphyxiationpain, breathing difficult, asphyxiation7575--200 mA200 mA possible ventricular fibrillationpossible ventricular fibrillation200200--300 mA300 mA certain ventricular fibrillationcertain ventricular fibrillation300+ mA300+ mA severe burns, heart stopssevere burns, heart stops

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Preventing Electrical Hazards• Electrical accidents appear to be caused by a combination of three possible

factors: unsafe equipment and/or installation; workplaces made unsafe by the

environment; and unsafe work practices.

• There are various ways of protecting people from the hazards caused by electricity.

• These include: insulation; guarding; grounding; electrical protective devices; and safe workpractices.

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Voltage is almost always a constant so electrical current levels are determined by the resistance to flow. When there is a potential for electrical shock we can protect ourselves by maximizing our resistance to current flow. This is done by wearing insulating shoes and gloves, and by not making direct contact with a source of ground potential such as plumbing or other sources of ground.

V = I RV = electrical potential (volts)

I = electrical current (amps)

R = resistance (ohms)

Ohm’s Law of Electricity

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Our skin provides us with a natural barrier or resistance of approximately 1,000 to 100,000 ohms depending on several factors including skin thickness and surface moisture.

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Lower levels of AC than DC will produce painful shocks in humans while lower levels of DC than AC can lead to fibrillation of the heart muscle. Women are more sensitive to the effects of both AC and DC than are men.

Effects of Electrical Shock on the Human BodyDirect Current Alternating Men Women Men Women

Perception Threshold 5.2 3.5 1.1 0.7 Painful Shock 0.5% 62 41 9.0 6.0 Painful Shock 99.5% 90 60 23 15 Ventricular Fibrillation 500 500 675 675All Units are in milliamps

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Extension cords are approved for temporary use only. If extended use is required, hard wiring such as a new outlet should be installed. Extension cords are easily frayed, a condition which may expose bare wires. If not properly placed, extension cords may also become a trip hazard.

Extension Cord Hazards

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Power cords are doubly insulated and should be replaced if the outer layer of insulation becomes frayed exposing wires.

Common Power Cord Problems

Exposed Wires

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Electrical Shock HazardsElectrical Shock Hazards

DonDon’’t use equipment with t use equipment with damaged insulationdamaged insulation

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Shorts cause a great increase in the flow of current through the cord producing heat and perhaps initiating a fire.

Overloads occur when more current flows through a cord than it is rated to handle. Power strips can be overloaded if too many high current draw devices are plugged in at one time.

ABCD

Outlet or Power Strip

Plug

Shor

t

Nor

mal

V = IR As resistance decreases, current increases.

Short circuit

Overloaded circuit

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Another common way in which power cords can be overloaded is by plugging one power strip into another. All of the current drawn by any device plugged into any of the strips must flow through a single cord

Overloaded Circuit

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Eyewashes should be located away from electrical devices and outlets. Outlets within six feet of a sink or other source of plumbing must be GFCI protected in order to minimize shock hazards. An unprotected outlet (non-GFCI) is illustrated above.

Outlet without GFCI

Water and Electricity

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A GFCI or ground fault circuit interrupter shuts off the flow of current upon sensing a fault condition such as an electrical shock. Switches quickly open in the GFCI device in order to prevent the shock victim from receiving a lethal amount of electricity.

SwitchesHot Line In

Neutral Line In

GFCIReceptacle

CurrentSensor

Function of a Typical GFCI

Load

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• A (GFCI) is an electrical device which protects personnel by detecting potentially hazardous ground faults and quickly disconnecting power from the circuit.

• Any current over 8 mA is considered potentially dangerous depending on the path the current takes, the amount of time exposed to the shock, and the physical condition of the person receiving the shock.

• A GFCI compares the amount of current in the ungrounded (hot) conductor with the amount of current in the neutral conductor.

• If the current in the neutral conductor becomes less than the current in the hot conductor, a ground fault condition exists.

• The amount of current that is missing is returned to the source by some path other than the intended path (fault current).

• A fault current as low as 4 mA to 6 mA activates the GFCI and interrupts the circuit.

• Once activated, the fault condition is cleared and the GFCI manually resets before power may be restored to the circuit

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Approved Treatment for Physical Shock Patients

1) Keep patient lying down

2) Keep airway open

3) Elevate patients’ legs if no bones are broken

4) Keep patient warm if conditions are cool or damp

5) Give fluids if patient is able to swallow

6) Never give alcohol to patient

7) REASSURE the patient

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Dry chemical extinguishers (also know as ABC extinguishers) are approved for fighting electrical fires. The label indicates the type of extinguisher that is present. Electrical fires should only be fought if the situation is well in hand. If you feel uncomfortable fighting a fire, pull the alarm and exit the building.

Small Nozzle

Test tag should be current

ABC indicated on label

Electrical Fires

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Preventing Electrical HazardsThese include: • Insulation• Guarding• Grounding• Electrical protective devices

• Safe work practices.

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Stay clear of bare wires.Stay clear of bare wires.

Use GFCIs, they save lives!Use GFCIs, they save lives!

Never retouch anything that Never retouch anything that has given you a shock.has given you a shock.

Protect cord insulation.Protect cord insulation.

Stay clear of power lines.Stay clear of power lines.

In Summary...In Summary...

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Thank youMade by:Jariwala Harekrishna H.Guided by:Tejas G. Misrty.