TOPIC 4: Electrical Safety Flashcards by Febbyjean Hartt Jumamoy

Q

The flow of electrical power or charge.
Causes 12% of young worker workplace deaths
About 5 workers are electrocuted every week.

A

Electricity

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Q

electrical movement (measured in amps)

A

Current

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Q

restriction to electrical flow

A

Resistance

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Q

a conductive connection to the earth which acts as a protective measure

A

Grounding

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Q

substances, like metals, with little resistance to electricity that alow electricity to flow

A

Conductors

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Q

substances with high resistance to electricity like glass, porcelain, plastic, and dry wood that **prevent electricity from getting to unwanted areas **

A

Insulators

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Q

measure of electrical force

A

Voltage

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Q

There are two classifications of electrical injuries:

A

direct
indirect

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Q

electrical injuries: direct

A

Electrocution due to electrical shock
Electrical shock
Burns

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Q

electrical injuries: indirect

A

Falls
Cardiac arrest

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Q

An () is received when electrical current passes through the body.

An () wil occur if a part of the body completes an electrical circuit by:
* Touching a live wire and an electrical ground *
* Static pressure build up within the body and touching something with a different pressure (example: Metal, wood, person)

A

electrical shock

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Q

SHOCK SEVERITY:
The severity of the shock depends on:

A

Path of current through the body
Amount of current flowing through the body (amps)
Duration of the shocking current through the body
Low voltage does not mean low hazard.

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Q

Effects of Electric Current in the Human Body

Below 1 miliampere

A

Generaly not perceptible

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Q

Effects of Electric Current in the Human Body

1 miliampere

A

Faint tingle

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Q

Effects of Electric Current in the Human Body

5 miliamperes

A

Slight shock felt; not painful but disturbing. Average individual
can let go. Strong involuntary reactions can lead to other
injuries.

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Q

Effects of Electric Current in the Human Body

6-25 miliamperes

A

Painful shock, loss of muscular control

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Q

Effects of Electric Current in the Human Body

9-30 miliamperes

A

The freezing current or “let-go” range. Individual cannot let go, but can be thrown away from the circuit if extensor muscles are stimulated.

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Q

Effects of Electric Current in the Human Body

50-150 miliamperes

A

Extreme pain, respiratory arrest, severe muscular contractions. Death is possible. 1,000–4,300 miliamperes

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Q

Effects of Electric Current in the Human Body

1000-4300
miliamperes

A

Rhythmic pumping action of the heart ceases. Muscular contraction and nerve damage occur; death likely. 10,000 miliamperes

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Q

Effects of Electric Current in the Human Body

10000 miliamperes

A

Cardiac arrest, severe burns; death probable

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Q

Among the most serious burns and require immediate medical attention.
Occur when electric current flows through tissues or bone, generating heat that causes tissue damage.

A

Electrical Burns

Q

Result from high temperatures
and pressure waves,
respectively, caused by an
** electric arc or explosion near
the body.** These burns should be
treated promptly.

A

ARC FLASH & ARC BLAST BURNS

Q

Caused when the skin touches
hot surfaces of overheated
electric conductors, conduits,
or other energized equipment.

A

THERMAL CONTACT BURNS

Q

When a person receives an electrical shock, sometimes the electrical stimulation causes the muscles to contract. This “freezing” effect makes the person unable to puLl free of the circuit.
It increases the length of exposure to electricity and because the current causes blisters, which reduce the body’s resistance and increases the current.

A

“Freezing” during shock

In addition to muscle contractions that cause “freezing,” **electrical shocks also can cause involuntary muscle reactions** These reactions can result in a wide range of other injuries from **FALLS** , including: (4)

* bruises * wounds * bone fractures * death

# Protection Against Electrical Hazards Electrical accidents are caused by a combination of unsafe factors including: (3)

* Unsafe equipment and/or instalation * Unsafe environment * Unsafe work practices

Protection Against Electrical Hazards (4)

1. Insulation 2. Guarding 3. Grounding 4. Circuit Protection Devices

Used to coat metals and other conductors **help stop or reduce the flow of electrical current.** This helps **prevent shock, fires, and short circuits.** (e.g. glass, mica, rubber, or plastic)

Insulation

Insulaion must be suitable for the voltage used and conditions (3)

* temperature * moisture * gasoline, corrosive fumes, or other substances that could cause the insulator to fail

Insulation Color coding

green/ green with yellow stripes - **Equipment grounding conductors** white/ grey - **Insulation covering grounded conductors** black/ red - **Ungrounded Conductors (Hot Wires)**

These are wires **specificaly designed to connect the metal parts of electrical equipment to the ground.** Their primary purpose is to **prevent electric shock** by ensuring that any fault current is safely directed to the ground, thereby protecting users and equipment.

Equipment grounding conductors

These are typicaly **neutral wires that return current to the power source.** They are connected to the ground at the main service panel, which **helps to stabilize the electrical system and provide a path for fault currents.**

Insulation covering grounded conductors

**Hot wires** are the **conductors that carry current from the power source to a device or appliance.** These wires are typicaly energized, meaning they carry live electricity, and **can cause electric shock if touched.**

Ungrounded Conductors (HotWires)

() involves **locating or enclosing electric equipment** to **make sure people don’t accidentaly come into contact with its live parts.** Effective () 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.

Guarding

**Recommended Locations:** * room, vault, or similar enclosure * a balcony, galery, or elevated platform; or a site elevated **8 feet (2.44 meters)** or more above the floor * Sturdy, **permanent screens** also can serve as effective guard

guarding

# guarding **Signages** **Conspicuous signs** must be posted at the entrances to electrical rooms and similarly guarded locations to alert people to the electrical hazard and to () e.g. “Danger”, “Warning”, “Caution”, “High Voltage Keep Out”

forbid entry to unauthorized people.

() **a tool or electrical system means intentionaly creating a low-resistance path that connects to the earth.** This prevents the buildup of voltages that could cause an electrical accident. () is normaly a **secondary protective measure** to protect against electric shock. It does not guarantee that you won’t get a shock or be injured or kiled by an electrical current.

Grounding

() **limit or stop the flow of current automaticaly** in the event of a ground fault, overload, or short circuit in the wiring system.

Circuit Protection Devices

** Open or break the circuit automaticaly when too much current flows through them.** When that happens, fuses melt and circuit breakers trip the circuit open. Philippines: 15-20 amps, 220 volts

Fuses and Circuit Breakers

**A fast acting circuit breaker designed to shut off electric power in the event of a ground fault** within as little as **1/40 of a second.** It works by comparing the amount of current going to and returning from equipment along the circuit conductors. **When the amount going differs from the amount returning by approximately 5 miliamperes, the GFCI interrupts the current.**

Ground-fault circuit interrupters (GCFI)

An () is an **unintentional electrical discharge or spark between two conductive surfaces,** often caused by damaged, corroded, or loose wiring, which **can lead to high temperatures and potentialy start a fire.** () differ from standard current flows and are **detected by Arc Fault Circuit Interrupters (AFCIs).** These devices **monitor the circuit for irregular current patterns, characteristic of arc faults,** such as sudden fluctuations or sparking sounds, and disconnect power if a fault is detected, preventing overheating and fires.

Arc-fault Devices

Electrical accidents are largely preventable through safe work practices. Examples of these practices include the folowing: (4)

* deenergizing electric equipment before inspection or repair * keeping electric tools properly maintained * exercising caution when working near energized lines, * using appropriate protective equipment.

An () is an **electric power transmission line suspended by towers or poles.** Since most of the insulation is provided by air, overhead power lines are generaly the **lowest cost method of transmission for large quantities of electric power.**

overhead power line

# Protection Against Overhead Power Lines * Ensure that you **maintain a safe distance to the lines** and, for very high voltage lines, ground any equipment such as cranes that can become energized. * **Ensure that the lines have been deenergized and grounded** by the owner or operator of the lines. * **Employees unqualified to work with electricity,** as well as mechanical equipment, should remain at least () away from overhead power lines. If the voltage is more than (), the **clearance increases by 4 inches (10 centimeters)** for each additional ()

10 feet (3.05 meters) 50,000 volts 10,000 volts

# Personal Protective Equipment Employees who work directly with electricity **should use the personal protective equipment** required for the jobs they perform. (7)

* rubber insulating gloves * hoods * sleeves * matting * blankets * line hose * industrial protective helmets

# Training for Employees All employees **should be trained to be thoroughly familiar with the safety procedures for their particular jobs.** Moreover, good judgment and common sense are integral to preventing electrical accidents. Basic procedures: (4)

* deenergize the equipment, * use lockout and tag procedures to ensure that the equipment remains deenergized * use insulating protective equipment * maintain a safe distance from energized parts

# Training for Employees **Electrical safe work practices training is required** for anyone working near energized, or potentialy energized electrical circuits of **fifty (50) or more volts to ground** to become () Training should also be provided to employees who are not exposed to energized parts, but operate electrical equipment

Qualified Electrical Worker

Mandatory () (or refresher) training is required a minimum of every **three (3) years or when conditions change.**

Retraining

# Sample checklist for basic electrical safety? **Inspect Cords and Plugs** * Check extension cords and plugs daily. Do not use, and discard cords and plugs if they are worn or damaged. * Have any extension cord that feels more than comfortably warm checked by an electrician. **Eliminate Octopus Connections** * Do not plug several items into one outlet. * Pul the plug, not the cord. * Do not disconnect power supply by puling or jerking the cord from the outlet. Puling the cord causes wear and may cause a shock

* Inspect Cords and Plugs * Eliminate Octopus Connections

# Sample checklist for basic electrical safety? **Never Break OFF the Third Prong on a Plug** * Replace broken 3-prong plugs and make sure the third prong is properly grounded. **Never Use Extension Cords as Permanent Wiring** * Use extension cords only to temporarily supply power to an area that doesnot have a power outlet. * Keep extension cords away from heat, water and oil. * Do not alow vehicles to pass over unprotected extension cords. Extension cords should be put in protective wireway, conduit, pipe or protected by placing planks alongside them.

* Never Break OFF the Third Prong on a Plug * Never Use Extension Cords as Permanent Wiring