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Electrical Installation - IModule 1: Electrical Installation

FundamentalsGrade 11

Allocated time: 2 weeks

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Class Objectives

describe the workplace electrical hazards and the importance of safe work practices.

define Personal Protective Equipment and the importance of wearing safety clothes.

define safe procedures for using ladders, scaffolds and tools during Electrical Installation.

identify the different safety signs, and explain their meaning. identify the different safety signs, and explain their meaning; 5. define the fundamental concepts of electricity such as current, voltage, resistance, circuit, power, conductors, insulators, AC and DC; 6. define the concept of ‘circuit’ and differentiate between series and parallel circuits. 7. troubleshoot faults in simple virtual circuits using the virtual multimeter and taking into account the safety precautions.

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Why Electricity is dangerous !!!

So lets find the hidden dangers !!!! http://www.cl-p.com/electricsafetyworld/in

dex.html

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Electrical Safety

Why electricity is dangerous? Electrical Shock Burns Explosion

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Electrical Shock

How the electrical shock happens ?› Electrical passing through human body

What does the severity of a shock depends on:› Current (10 mA)› Voltage

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Electrical Shock A man receives a shock in two cases:

Current flows between parts of the body

Current flows through body to ground

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Electrical Shock

The severity of a shock depends on:› Amount of current.› The current’s path.› The length of time.

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Electrical Shock

Online Activity› http://

kerala.skoool.in/content/KS3%20LOs/science/electricity_rules/index.html

Homework

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Working Safely

In order to work safely you have to do the following:› Wear safety clothes› Use ladders and scaffolds correctly› Operate tools safely› Practice safe work habits

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Working Safely: Personal Protective Equipment (PPE)

What is PPE ? What are the basic

pieces of PPE ?› Gloves› Glasses› Shoes› Flame-resistant

clothing› Hard hat› Earplugs› Face shield

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Working Safely: Ladders & Scaffolding

To access a working area you may need a ladder or a scaffold.But you can’t use them without

supervision or training !!!!!!!

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Working Safely: Ladders

Tips to follow when you use a ladder:› Made of wood or

fiberglass (But Why ???)

Nonconductor

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Working Safely: Ladders

Should be set at a safe angle (Why???)

Avoid slipping or falling

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Working Safely: Ladders How to position the

ladder (safe angle)?› Use a simple

calculation› W= ¼*h

Find the horizontal distance (w) when the ladder touches the wall at a height (h=20m) ???› W= ____________ m

h

W

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Working Safely: Ladders

The ladder must have a firm support.

Use a ladder leveler

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Working Safely: Scaffolds

Tips to follow when you use a scaffold:› Wooden› Wheels must be

locked to prevent movement

› A ladder must be used to get onto it.

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Use of proper tools Tips to be used before

using electricity:› Switch OFF the power

before plugging the power socket.

› Change damaged cord

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Use of proper tools

Use Insulated tools when required to

work when the power is ON

Insulator

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Safe work methods Wear safety clothes (PPE). Turn the power off, and never work on

energized equipment unless it is absolutely necessary.

Use proper equipments and tools. Maintain good housekeeping (Why ?)

› Do not leave tools lying around the benches or workshop: to avoid tripping hazards, and lost tools and

materials. Take precautions to avoid fire (As what ?).

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Class ActivityFind the 7 deliberate mistakes (Fill in your

Table) !

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Safety Signs

Colored Signs & Logos Displayed at the workplace Provide safety awareness They must be obeyed strictly Different types of safety signs:

› Warning Signs› Advisory/Safe Condition Signs› Mandatory Signs› Prohibitive Signs› Signs for Fire Safety

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Warning Signs

Warn of any type of hazards

Triangular yellow with a black border.

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Advisory/Safe Condition Signs

Provide information about safe conditions.

They are square / rectangular green signs with a white symbol

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Mandatory Signs

Indicate that a specific course of action must be taken

Circular blue signs with a white symbol

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Prohibited Signs

Indicate that a certain behavior is not allowed

circular red signs with a black symbol

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Signs for Fire Safety

Shows the location of fire fighting equipment.

They are either square or oblong with a red background.

Examples include: fire alarm control, fire alarm do not switch off!

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Class Activity (Skill 2) Identify the following safety signs and

indicate the type to which they belong.

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Cont. Class Activity (Skills)

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Electrical Energy Fundamentals

Current: Current is the flow of electrons.

› With no voltage applied, there is no current flow.

› With more voltage applied, a larger amount of electrons will flow, which means a higher current.

› Unit: ampere (A)› Measured instrument: Ammeter.

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Electrical Energy Fundamentals (Current)

Current flow in a circuit

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Electrical Energy Fundamentals (Voltage)

Voltage: The driving force that causes electrons

to move through a conductor.› Called also: electromotive force (emf)

unit: of volt (V) Measured Instrument: A voltmeter

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Electrical Energy Fundamentals (Resistance)

The opposition to the flow of current through the conductor

Unit: ohms (Ω).› Like other forms of friction, resistance is

responsible for creating heat and loss of power.

Measured Instrument: Ohmmeter.

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Types of electric current

There are two types of electric current, depending on the direction of the current:

Direct Current (DC): current flows in one direction only.

Direct Current is provided by batteries and is used in battery operated devices such as flashlights, automobiles,…

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Direct Current

DC Circuit

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Types of electric current

Alternating Current (AC): it continually reverses the direction of flow.

This change in direction is represented by the sine wave.

voltage supplied to houses and businesses in the UAE is 230V.

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Alternating Current (AC)

AC Circuit

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Electrical Energy Fundamentals ( DC Power Supply)

Converts AC voltage from the power lines to a constant DC voltage regulated at various voltage levels.

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Electrical Energy Fundamentals (Power)

Power: The electrical power determines how fast a certain amount of energy is consumed by a load.

Unit: Watts, kilowatts (1,000 watts) and megawatts (1,000,000 watts).

Power is calculated using the formula,› P = VI = I2R = V2/R.

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Electrical Energy Fundamentals (Energy)

Electrical energy is measured in power-time units

called watt-hours or kilowatt-hours (kWh). 1kWh = 1000 watts power being used for one hour.

i.e: The energy consumed by a 100W lamp that is turned on 5 hours is W = P X t = 100 X 5 = 500 watt-hours.

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Electrical Energy Fundamentals (Conductors and Insulators)

Conductors : a material that allows current to flow through it easily

Insulators: a material in which current movement is difficult

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Electrical Energy Fundamentals (Multimeter):

A multimeter is used to measure current, voltage and resistance in an electrical circuit.

A Digital multimeter (DMM) provides a digital readout of the measurement quantity.

Some digital multimeters also offer the ability to test some electronic components.

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Multimeter: How to measure the current

To measure current using a DMM through the resistor circuit must first be broken.

The DMM must be set as an ammeter (the round function switch should be in the DC A position), and it must be connected in series with the circuit

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Multimeter: How to measure the Voltage

Voltage is always measured relative to some other point in a circuit.

To measure voltage across the resistor, the DMM must be set as a voltmeter (the round function switch points to the DC V position), and must be connected across / in parallel with the component

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Electric Circuit: In a water system, the pathway is the piping, which

moves the water from storage to where it is used. In electrical systems, the wires form the pathway

for current to flow. A simple electric circuit consists of the following

elements:› Power Source: For a residence, the electrical

generating stations could be considered the power source. However, batteries could be considered as primary power sources.

› Conductors: Wires provide a path for the current to travel.

› Loads: These are devices through which the electricity produces work. Examples: Lamp and Motor.

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Devices for controlling current

These devices include switches, fuses and circuit breakers.

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Loads

A load is any device that uses an electric current and converts the energy to another form. Loads include the following:

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Types of circuits

Series Circuit: In a series circuit, only one path is provided for the current to flow. The electricity flows through every device in the circuit, and if one device burns out, the circuit will not function.

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Types of circuits

Parallel Circuit: The parallel circuit has more than one path available for the current to flow. Each path goes to a load that can operate independently of the other branches and loads in the circuit. If one load, such as a lamp, burns out, the other branches would continue to operate.

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Types of Circuits

Loads such as lamps, heater, or motors may not operate properly in a series circuit, and are therefore usually connected in parallel. Only switches, fuses, and circuit breakers are generally connected in series.

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Lab Activity (1-8)

Simutech TEC software/ Edison