Lesson

LESSON TITLELesson

LESSON TITLELesson 101

Orientation and Basic Principles

Purpose

In this lesson, students will receive a brief overview of both instructor and student obligationsto the apprenticeship training program. The lesson will also discuss the advantages of being part of the Independent Electrical Contractors (IEC) apprenticeship program and will introduce the law of electric charges and theories of current fl ow.

Homework (Due at the beginning of this class)

For this lesson, you should: • Thoroughly read the material contained within Lesson 101.• Complete Objective 101.3 Worksheet.• Complete Lesson 101 NEC® Worksheet.• Read and complete Lesson 101 Safety Worksheet.

ObjectivesBy the end of this lesson, you should:

101.1 Possess a working understanding of the apprenticeship policies and procedures of the IEC chapter sponsoring your training program.

101.2 Evaluate the advantages of being part of the IEC apprenticeship program.101.3 Develop a basic comprehension of the law of electric charges and theories of current fl ow.

Electrical Curriculum

Year One 2010-2011Instructor Manual

101-2 Orientation and Basic Principles

101.1 Chapter Policies and Procedures

15 minutes

At this point, thoroughly explain the layout and importance of the student manual. Homework assignments are listed at the beginning of each lesson. These assignments are to be completed prior to that class. For example, before the next class the students should have completed the homework shown at Lesson 102-Homework.

Take time to verify that each student’s “book kit” is complete. Explain the layout of additional student material. Emphasize that students should bring a pencil (or pen), extra paper, and a calculator along with the required textbooks to each class. Each student should also check the “Tools” section for each lesson to determine if additional tools should be brought to the next class.

The instructor should review next week’s material before assigning the worksheets for that lesson to determine if students will require additional instruction.

Read your chapter’s policies and procedures to understand:

What you can expect of the instructor• Your rights as an apprentice• Your responsibilities as an apprentice•

Attendance• Homework• Class participation•

45 minutes

Discuss how you will conduct your class. You should expect mutual respect among all parties: they should arrive on time, be prepared, act properly, etc.

Explain when you expect homework to be submitted. Explain that quizzes may be over material covered in class or assigned as homework. Point out to students that you will not be reading their reading assignments to them. The reading assignments are not optional. These will not necessarily be covered in class. You will discuss only the more diffi cult to comprehend material and answer any questions the students might have. However, exam questions WILL include material addressed in the reading assignments, homework exercises, and lecture.

Consult your instructor policies or get copies of your chapter’s apprenticeship policies and procedures from your supervisor.

Year 1 2010-2011 (Instructor Manual)

Orientation and Basic Principles 101-3

101.2 Advantages of the IEC Apprenticeship Program

IEC was formed in 1957. It is a nationwide association of merit shop electrical contractors with the primary purpose of providing quality training for apprentice electricians, using a curriculum recognized by the United States Department of Labor.

IEC promotes pride in workmanship and development of qualifi ed electricians.

IEC (merit shop) contractors compensate their employees based on merit, that is: ability, experience, and work ethic.

Apprenticeship consists of fi eld training concurrent with classroom instruction. IEC Apprenticeship offers apprentices the opportunity for faster advancement than training programs that rely solely on fi eld training. Instructors have the support of IEC through continuous training at both local and national conferences.

You may frequently see the IEC PRIDE logo. P.R.I.D.E. stands for Promoting Responsible Independent Dedicated Electricians.

The purposes of the P.R.I.D.E. campaign are to:

• exceed our customers’ expectations both in quality of product and service• provide a working environment that promotes teamwork• to promote the concerns of electricians proud to identify themselves as “independent”• provide a safe workplace • encourage personal growth• expand the skilled labor force• promote professionalism in your company through quality management• infl uence state and federal legislation• support usage of the National Electrical Code (NEC®)

30 minutes

Emphasize that the “independent” philosophy holds great value for those who are willing to put forth their best efforts and accept nothing less.

Year 1 2010-2011 (Instructor Manual)

101-4 Orientation and Basic Principles

101.3 Electric Charges and Theories of Current Flow

Electron Theory

Elements of an AtomAll matter is composed of molecules. Molecules are comprised of different atoms. Each atom has a nucleus with electrons orbiting it. The nucleus is composed of protons and neutrons. (The neutrons are not shown in the drawing at the right.) Generally, there are an equal number of electrons and protons in each atom. The electrons have a negative charge (−), and the protons have a positive charge (+). Neutrons carry no charge. The positive charge of the protons balances the negative charge of the electrons, and the electrons are held, or bound, in their orbit by this equal attraction. These electrons are referred to as bound electrons.

Free ElectronsThe electrons traveling around the nucleus in the outermost orbit are not as strongly held as those electrons that are in an orbit that is closer to the nucleus. These are called free electrons.

Consider NASA’s mission to send astronauts to the moon. First, the spacecraft was put into orbit around the earth. They initially didn’t “fly into space” because of the gravitational attraction of the Earth. Then their orbit was progressively expanded: they became less and less attracted to the Earth as they moved farther away from it. Then, when they applied sufficient force with their engines, the spacecraft did indeed overcome the Earth’s attractive force that held it in orbit, and away they went into space. Very careful planning went into this action. They timed the engine thrust so that their trajectory headed them toward our moon. When they got close enough to the moon, the moon’s gravitational force captured them in orbit around it.

Just like the spacecraft, free electrons can be forced out of their orbit around an atom and can be “captured” in the orbit of an adjacent atom. Instead of an onboard engine, however, an external

Year 1 2010-2011 (Instructor Manual)

Orientation and Basic Principles 101-5

force must be applied to get these electrons out of orbit. The external force can be due to chemical action, friction, or by a magnetic field. When a free electron leaves an atom, it leaves behind a “hole” or void into which a free electron, from an adjacent atom, can enter.

Magnetism is the basis of electricity. Oppositely charged particles attract each other, and particles that have the same charge repel each other.

(+)(−) (−)(+) and (+)(+) (−)(−)

Since electrons are negatively charged, the introduction of a negative force from a magnetic field will cause the free electrons to move away from the negative source. When this negative force is applied to a material, electrons can be forced out of orbit and pushed away from it. These free electrons will travel until they see a “hole” vacated by another free electron. Free electrons “flow” through a material from one atom to the next. This flow of electrons is termed “current flow.” Current flow is what makes all electrical equipment operate.

CurrentCurrent is the flow of electrons from one atom to another. Current flow is actually millions of electrons moving through a conductor. The number of electrons moving past a point in a conductor in a second’s time indicates the current INTENSITY. This is why current, as used in a calculation or formula, is abbreviated as I. So, I = current. Current is measured in amperes, or amps, using an ammeter. An amp, or ampere, is abbreviated as A. When 6.24 x 1018 (6,240,000,000,000,000,000) electrons are moving past a point in a conductor in a second’s time, then 1 amp of current is flowing. Some currents (as in electronics) can be very small, and some currents (as in power generation) can be very large. These quantities are frequently written in metric equivalents.

For example: where A = amperes = amps 1 microampere (abbreviated: μA) = 1 ÷ 1,000,000 A = .000001 A 1 milliampere (abbreviated: mA) = 1 ÷ 1,000 A = .001 A 1 kilo ampere (abbreviated: kA) = 1 x 1,000 A = 1,000 A 1 mega-amp (abbreviated: MA) = 1 x 1,000,000 A = 1,000,000 A

Direction of Current FlowAs previously stated, electrons (e−) are negatively charged and will flow toward a positively charged terminal. For example: An electrical circuit is formed when the positive (+) terminal (or post) of a battery is connected to a piece of wire, this wire is then connected to one terminal of a lamp (“light bulb”), the other lamp terminal is connected to another piece of wire, and this wire is then connected to the negative (−) terminal (or post) of the battery. Because “likes repel” and “unlikes attract,” electrons will leave from the negative battery terminal and travel through the wire, the lamp filament, through the other wire, and back into the battery through the positive terminal. This cycle is repeated.

Year 1 2010-2011 (Instructor Manual)

101-6 Orientation and Basic Principles

Electrons will flow between two points whenever there is a difference in potential between the two points. This electron flow is current flow.

VoltageAs stated before, a force must be applied to cause the electrons to move. Electricity is frequently compared to water flowing through a pipe. A force is required to cause water to flow in the pipe. This force could be from a pump or simple gravity (as from a water tower). The stronger the pump, the more water will flow. The bigger the pipe, the more water will flow. The same is true for electron flow.

The force required to cause electrons to flow in a circuit is called electromotive force or emf and exists because of the difference in potential between two points. Voltage is the most common term used to describe this force. Either E or V represents voltage in a calculation or formula. Voltage is measured in volts using a voltmeter. The unit of measurement for voltage is volts and is abbreviated V.

Various means can be used to generate voltage. Storage batteries can be used. This is an electrochemical process where excess electrons on the negative battery terminal are transferred to the positive battery terminal by traveling through the conductors and various loads that are connected between the two terminals. These batteries can be re-charged with a charger that is powered from various sources, including wind, water, sunlight, or another power source. A schematic of a battery and lamp circuit is shown at the near right. The terminals of the battery are represented by two lines, with the shorter line representing the negative terminal.

Another power source of limited capability is a thermocouple. When two dissimilar metals are joined at one end and the junction is heated, a small thermoelectric voltage is generated. Thermocouples are used in natural gas environmental air heating units, cooking equipment, and water heaters. When exposed to the heat of a pilot light, these thermocouples generate just enough voltage to power the gas solenoid valve circuit and hold the valve open to allow the unit to operate. When heat is removed (pilot light goes out), the thermocouple stops generating voltage. The solenoid valve closes, thus shutting off the gas supply to the equipment.

ConductorsA material that consists of molecules that allow many electrons to move freely is called a conductor. Conductors are classified according to the number of electrons allowed to travel freely. Remember, this is current flow. Most metals are excellent conductors. These include copper, brass, silver, aluminum, platinum, gold, and zinc. Copper is the most commonly used among these for electrical equipment because it is relatively inexpensive and also because it has other desirable physical characteristics that are required for product manufacture and use.

battery

lamp

e-e-

Year 1 2010-2011 (Instructor Manual)

Orientation and Basic Principles 101-7

InsulatorsSome materials allow very, very few free electrons (remember—current flow). These are called insulators. Materials that are good insulators include some plastics, rubber, glass, mica, some ceramics, and air.

Electricians make use of both conductors and insulators. Lineman’s pliers are often constructed of steel (a conductor) with plastic (insulator) high dielectric covers on the handles. Another example of the use of both conductors and insulators is in the construction of electric cables used to supply electric power to equipment. Electricians call these “conductors” or “wires.”

Remember that some materials are not conductive but can be made conductive. Listed below are some examples of this:

a) Clean and dry wood is an insulator but can become conductive if soaked with a somewhat conductive liquid, such as dirty water. Be aware that plywood is made from thin sheets of wood glued together. This glue may contain conductive materials. Insulating mats, made for the purpose, should be used for “hot work.”

b) New leather boots with rubber soles are good insulators. But sweaty, dirty boots are NOT good insulators because sweat is salty and therefore a conductor.

c) Pure distilled water is a perfect insulator. However, as chemicals such as chlorine, or salt, or other contaminates such as dirt are added, it becomes more and more conductive. For this reason, you would not put your body or any body parts into tap water or dirty water to operate energized electrical equipment.

d) The dust covering insulated electrical wires in a panel will allow current to flow through the dust particles. This can be very dangerous to electricians and is why electrical equipment and conductors must be enclosed and kept free of dust and dirt.

For the reasons listed above, our insulated safety equipment must be kept clean and free of conductive contaminates. Keep this in mind when you inspect your equipment prior to using it! When you get ready to trust your life to a rubber mat or gloves, are you wondering what cleaning solution was used to clean it? Was the cleaning solution conductive, or did it leave a residue that is conductive?

The most common source of voltage is a generator (or alternator). Generators produce voltage when the center shaft is turned (or rotated) by an external force. External forces include wind; hydroelectric (due to gravity); wave motion (due to wind and tides); and internal combustion engines that use natural gas, gasoline, diesel, coal, etc. Look under the hood of your car. You will find a generator that has its center shaft turned by the rotary action of the engine.

Year 1 2010-2011 (Instructor Manual)

101-8 Orientation and Basic Principles

As with current, voltages can be very small or very large, and metric equivalents are used to represent these quantities.

1 microvolt (μV) = 1 ÷ 1,000,000 V = .000001 V 1 millivolt (mV) = 1 ÷ 1,000 V = .001 V

1 kilovolt (kV) = 1 x 1,000 V = 1,000 V 1 megavolt (MV) = 1 x 1,000,000 V = 1,000,000 V Let’s review the elements of an electric circuit we have covered so far. These are current and voltage.

When the voltage source has two terminals, with one marked + and one marked − (as with a battery or a dc power supply), the voltage is constant. This voltage and the circuit current are termed DC for direct current. When the voltage source is a generator or a transformer, the circuit voltage and current are termed AC for alternating current. You will learn more about AC in your future studies.

60 minutes

Students need to completely understand the principles set forth in this objective. You should use Objective 101.3 Worksheet for reinforcement. This worksheet can be used during class or assigned for homework. Students may have diffi culty with metric prefi xes, so ample time will have to be allotted.

For your reference, additional materials such as Electrical Principles and Practices, Delmar’s Standard Textbook of Electricity, or Electricity 1-7, may be available to you from your supervisor.

Materials required for this lesson: None

Year 1 2010-2011 (Instructor Manual)

Orientation and Basic Principles 101-9

Tools Required for this Lesson: None

Demonstrations —Samples—Activities—Labs

30 minutes Demonstrate DC current and voltage measurements to reinforce the discussion of Objective 101.3. You will need to have an “in-line” ammeter (capable of DC current measurement), a voltmeter, a battery, and a load (fan, annunciator, light, etc). A fl ashlight could be substituted for the battery and load.

Equipment: DVD, VCR, Internet Websites, etc.: http://www.sea.siemens.com/step/default.html.

NEC®

30 minutes Complete Lesson 101 NEC® Worksheet.

Safety

15 minutes Discuss Lesson 101 Safety Worksheet.

Summary

15 minutes Recap tonight’s discussions, and give a brief synopsis of the next lesson. Return and discuss graded homework from the previous lesson. The homework listed at the beginning of the next lesson is due at the beginning of that class. However, the instructor should review the material in the next lesson in advance to determine if some of the worksheets require discussion before being assigned as homework.

During the school year, you may fi nd that a particular lesson does not require the entire class period to complete. In these cases expand your synopsis of the next lesson to take advantage of the available class time. This will enable you to complete all assignments because some lessons will require more than one class period to complete.

Assessment – Quiz for this lesson is Optional.

Refer to the Assessment Bank questions and problems for quizzes. Where the assessment banks include worksheet questions, these are so noted.

Year 1 2010-2011 (Instructor Manual)

101-10 Orientation and Basic Principles

Lesson 101 Safety Worksheet

form #5100-048-01, rev date 3/10/06

Year 1 2010-2011 (Instructor Manual)

Orientation and Basic Principles 101-11

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Year 1 2010-2011 (Instructor Manual)

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