Sciences Subject (BS 21001)

351 2. Tools for electricians Tools and instruments used by electricians are as follows; 2.1 Screwdriver is classified to 2 types that are 1) Common screwdriver 2) Phillips-head screwdriver or Crosshead These screwdriver tips are available in a large variety of sizes and thickness owing to engaging with the head of a screw having the same size as the screwdriver itself. Normally, you turn a screwdriver clockwise to tighten a screw. In contrast, you turn a screwdriver anticlockwise to loosen a screw. The other types of screwdrivers are spark detecting screwdrivers which have a hand-held test lamp used to test electric circuits.

352 2.2 Knife Most of knives used by electricians are pocket knives or cutters in order to peel off, cut, or notch electrical insulations. The ways of using knives to peel off electrical insulations properly 1. Use a knife to notch a wire cover. 2. Cut in the middle of cover. 3. Separate the wires. 2.3 Pliers are a hand-tool used to compress, cut, or roll the wires. They can be divided into; 1) Pliers are side cutting pliers used to cut curly wires, deform curly wires, and short transmission lines. 2) Needle-nose pliers are used to hold, pull, and bend the small wires.

353 3) Flat nose pliers are used to cut, squeezee, or make a knotted wire. 4) Round nose pliers are commonly used for creating loops in pieces of wire (roll the wire for holding to the main lines) 5) Cable stripping pliers are used to strip insulation, deform curly wires, and transmission lines. They allows the user to only match the notch size to the wire size. A handheld should be covered with insulation such as plastic for preventing electric shorck from a leakage current or residual current. 2.4 Drill is used for attaching electrical itmes like switches, lamps, and wooden boards which are held by knots or screws and needed to drill holes by using drills or gimlets. There are three types of drills that are 1) Brace drill

354 2) Hand drill 3) Electric drill In order to choose drills and drill bits to match the sizes of power tools and the particular work. If it is soft wood such as drilling a wooden board, hand drills or brace drills can be used. Alternatively, electric drills are required if you do the job on metal or concrete. 2.5 Hammer is a tool used to drive nails for holding a clip to the wall or forge metal, concrete, or cement floors. Hammers are vary in their size and weight. The most common used hammers are 200 gram hammers. Caution The head of the hammer should be tightly affixed to the handle. Additionally, the hammer head shall be coated with acrylic resin. 3. Electrical circuit tools 3.1 Electrical wire is a tool used for tranmission of electrical power from one place to another. The electrical current will carry the electricity through the wire to appliances. The wire is made of a conductive material (allow the current to flow through) such as; 1) A high voltage cable is made from aluminum. Because aluminum is much cheaper and lighter weight than copper. 2) An electric utility cable (used in home wiring) is made of copper. As copper is cheaper than silver.

355 insulation A. Heat resistant cable has a heat resistant resistant insulation like an iron cord. B. Twisted pair cable is used in home wiring wiring. C. Twisted pair cable is used in Household appliances e.g. radio, Television. D. Single strand wire is pulled into an electrical conduit. 3.2 Fuse is tool that acts as a scificial device to provide overcurrent protection. If there are an overcurrent situation, a fuse will interrupt excessive current automatically. A fuse wire is made up of alloy of lead and tin, with bismuth which has a low melting point, a high electrical resistance, and a variable form dependging on the usage. 3.3 Switch is an electrical component that can break or connect an electrical circuit. A swith works like a cut-out by connecting in a serires circuit to appliances. There are 2 types of switches that are a one-way switch and a two-way switch.

356 3.4 Circuit breaker is used to break or connect an electrical circuit consisting of a mounting plate and a switch which is a bimetallic strip and has an insulated handheld. When the switch is turned on to the channel of conductor, the current will flow from a wattmater to a circuit. On the other hand, when the switch is turned off, the current will stop flowing. 3.5 Starter is a tool besides a main switch used to break or connect the filaments at the end of the tube. Starters are classifed into 2 types that are; Type 1 Starter without operating time limitation Type 2 Starter with operating time limitation is divided into 3 types as follows; 1) Non-resettable 2) Resettable 3) Automatically resettable starter activated by a main switch or the other ways designed for the igniting purpose.

357 3.6 Electrical ballast has the property of increasing the potential difference, and the high resistance of an alternating current (AC). The common used ballasts are separated to 2 types; 1. electromagnetic ballasts 2. electronic ballasts 1) Electromagnetic Ballast contains a magnetic core of several lamintaed steel plates wrapped with copper windings working as a reactor connected in series to the bulbs. Figure shows electromagnetic ballasts. 2) Eletronic Ballast uses electronic circuitry which is expensive. However, elctronic ballasts are better than electrromagnetic ballasts that are to help to increase the eficiency of lamps without blinking or flickering, can turn the light on immediately without using a starter, increase the bulb’s lifetime, and is not required to improve power factor (P.F.). Moreover, these ballasts are sound proof and light weight. Figure shows electronic ballasts. 3.7 Electricity meter You can test the current in a wire by hanging a magnet close to the wire and observe the declination of the magnet. This idea was introduced to make an electricity meter. The declination of a meter needle on a meter’s scale will show the amount if current which is able to measure the potential difference.

358 A galvanometer is an instrument for detecting a direct current (DC) and using the principles of magnetic field. The simple instrument to check the current flowing through a wire is a compass placed near the wire. A moving coil galvanometer is based on the motor principles to decline the meter’s needle. An ammeter is an instrument used to measure the electric current in a circuit which is made of a moving coil galvanometer designed to deflect the pointer to the scale in order to measure the high power current, shunt is required to increase the current resulting in the full scale deflectin of the pointer. A voltmeter is an instrument used for measuring electrical potential difference between two points in an electric circuit which is made from a galvanometer by inserting a high resistance resistor in series and providing the current which deflect the needle to a full scale. In order to measure the high potential difference, it is required to use a multiplier. A multimeter is a galvanometer connected to a shunt (See an ammeter) and a multiplier (See a voltmeter) used to measure current and potential difference (voltage). A moving iron meter is an instrument to measure an electric current relative to the magnetic induction; attracting or repelling, resulting in the magnet deflection. 4. The connection of an electrical circuit An electrical circuit is a path in which electric current flows. The movement of electric charge is produced by connecting the power source to the conductive wires and one or more electrical instruments such as a resistant switches, ammerters, voltmeters, or bulbs etc. The current will flow from the power source in the connected circuit.

359 An electrical circuit is connected to the electrical instruments and a diagram of an electrical circuit. Electrical symbols are used by scientists to represent various electical devices in an electrical circuit to draw and understand them easily. The table of electrical symbols are shown below. The connection of electrical circuits are classified into 2 catagories as follows;

360 1. The connection of series circuits The series connection is a circuit in which the electrical devices are connected to the power source directly. There is only one circuit. However, the disadvantage of a series circuit is that if one of electrical devices breaks down, the current will stop flowing due to the current flowing in one path. The other devices can not be used. The summary of key characteristics of a series circuit connection 1. Calculate the total resistance by adding up the resistance value. Hence, the total resistance will increase. 2. The amout of current flowing through each resistor is equal to the amount of current in a circuit. 3. The potential difference between two ends of resistors is equal to the sum of potential differnce across each resistor. 2. The connection of parallel circuits The connection in parallel is an electrical circuit that each device is separately connected to the power source. There are many citcuit patterns as shown in the diagram below. The benefit of a parellel circuit is that if one of electrical devices connected in parallel breaks down, the current will still be flowing through the other devices in the circuit.

361 To connect 2 light bulbs by connecting wires to one light bulb and put across the pole of the other bulb is called a parallel circuit. The amount of current from the power source will flow to each device unequally based on the resistance of them. If they have the high resistance, the small amout of current is allowed. In contrast, if the devices have the low resistance, the amount of flowing current will be high. In addition, the sum of current flowing through each device added together is equal to the total current flowing out of the power source. The calculation beasde on the Ohm’s law is required to determine the value of resistance and the amount of current flowing in a parallel circuit. The summary of key characteristics of a parallel circuit connection 1. The total resistance of a circuit has the lower value which is less than the lowest resistor connected in parallel. 2. The total amount of the current is equal to the sum of current in all individual circuits added together. 3. The potential differece between two ends of each resistor is the same value and euqal to the potential difference between two ends of resistors connected in parallel. 5. Ohm’s law The electric current flowing in a circuit is produced by the voltage distributing the electric charge to the circuit. The amount of current in the circuit will be limited by the resistance. Therefore, the amount of current depends on the voltage and the resistance called the Ohm’s law which states that the current flowing in a circuit varies directly with the voltage and varies inversely with the resistance. Here below is the equation that describes this relationship: Current = Voltage Resistance I=V R

362 Example Calculate the current of an electrical circuit that has voltage supply of 50 Volts and resistance of 5 Ohms. Solution According to the formula I = V R Replace I = 50V 50 I = 10 Amperes Experimental instruments 1. DC power supply set the output voltage to 0.3 V 2. Multimeter 3. 3 variations of resistors 4. wire Experiment 1. Connect a resistor to the DC power supply set the voltage as the figure shown. 2. Adjust the 5 values of the output voltage. Measure current in each of voltage adjustment. Record data. 3. Calculation 4. Draw a graph between V and I as figure shown. 5. Calculate the slope of a line comparing the value to No.3 and the resistors. Conduct the experiment following No. 1-4.

363 Question Does the value of V according to the experiement follow the Ohm’s law? I Why? 6. Electrical wiring There are two types of wiring methods which are on-wall and in-wall wiring. 6.1 On-wall wiring In order to run the on-wall wiring, the wire will be seen resultin in an unpleasant view. If an electrician can not connect the wire in a straight line, it may make a room disordered. Plus, it is hard to decorate the room beautifully. The advantages of this method that are cheaper than an in-wall wiring and easily to trace and fix. Step 1 Determine the position of an electrical outlet and the wiring direcetion which shall be in the same wiring line. In case there is open wiring, you can use the early line, then separate to the desired position later. Step 2 To wire the new line. Firstly, you shall run the line through the ceiline. Then, wire the line to the desired position. Use the tape measure to plot out a clean line. Step 3 Nail clips along the plotted line to the wall and the new set line. Fold the clip to cover the nails’ head for holding while driving nails. Step 4 leave a space bewteen each clip about 10-15 cm. Nail it more frequently around 1-2 cm in the joints of the ceiling in order to attach the line tightly to the wall. Step 5 Install the outlet at the new position. Use the electric drill to drill the outlet plate and screw it tightly. If it is a wooden wall, put a wooden structure to strengthen the wall. Step 6 Run the wire to the clip line and strap it to the clip firmly. Connect the wire to the outlet.

364 Step 7 Turn off the main switch. Chech that there is no current running to the outlet by using a voltage tester screwdriver. Then, connect the line to the outlet and turn on the main switch. After that , use the voltage tester screwdriver to detect the current at the new outlet. 6.2 In-wall wiring An in-wall wiring is a way to run the wire through the conduit which is in the wall of the buildings and makes the room more organized and easy to decorate. To run the wire through the conduit has to go together with the bricklaying and cement rendering. It is necessary to get the line through the conduit. If there is a leakage current, it will cause an accident to residents when they touch the wall. The installation of the conduit is more expensive than an on-wall wiring. Besides, it is more complicated. The changing and repairs after the installtion is difficult and more costly than the first type of wiring. The open wiring is installed in the wall while the plumbing is installed along the edge of the floor and wall. In case of pipeline damage, the detection and repair can eaily be done. However, the modern houses are built more meticulously. It will have the wiring run through the conduit which is installed in the wall or above a suspended ceiling, while the plumbing is installed undeground or sub-floor in order to hide the messy wire and pipes. Although these wiring and plumbing make your home organized and beautiful, there are disadvantages. If there is an electrical short, a leakage current, or a leaking pipe resulting from using poor quality materials, incorrect installation, or damage due to the usage, it will be difficult to detect and repair. It might have an effect on the house structure, such as, pulling down the ceiling or dismantling the wall for detecting and problem solving. Plus, it is costly to install an electric system. The simple solution is to run the open wiring which may look messy and is only suitable for small houses. Alternatively, for those who prefer beauty or the larger houses which have a lot of wiring run shall install an in- wall wiring. However, the problems can be prevented or reduced by using the high quality materials and the correct and right size materials including the proper installation. The home’s electrical system shall be separately controlled, such as, divided by floors or types of electricity usage. These are easy to repair in case of a power outage. The electrical system should be separated in each room. If you have to turn off the light in the house for repair, it is not required to shut down the eletrical system in the kitchen which has a refrigerator containing foods.

365 7. The simple use of electrical appliances Electric light - Install light bulbs as necessary and suitable for use. - Use light bulbs which provide much light but are energy-saving, and have long-life such as a compact fluorescent light bulb or a fluorescent lamp etc. - Always clean light bulbs or lamps. - Paint light colors to increase the light reflectance. - Turn off lights when they are not in use. Fan - Select the right size and model of fans for usage. - Adjust the fan speed moderately. - Turn on fans when it is necessary. - Keep a fan in good condition. Television Set - Choose the right television size for the family and the room. - Select to watch one television program in a time or turn it on when the show is on. - Unplug the televisions when they are not in use. Hair dryer - Blow-dry when your hais is damp. - Comb you hair with your fingers while blow-drying. - Blow-drying on a high temperature setting when necessary. Electric iron - Sprinkle water on clothes before ironing. - Set the heat for the fabric you are ironing. - Start ironing a clothing with a thin material while the iron is warm. - Do ironing when there are a large amount of clothing. - Unplug an iron 2-3 minutes before you finish iron because the heat still remains.

366 Coffee machine - Pour water moderately. - Close the lid of the coffee machine before boiling. - Turn off the coffee machine immediaetly when you are finishing brewing. Electric rice cooker - Select the appropriate size for your family. - Unplug the rice cooker after it is done or it is not required to be warmed. Refrigerator - Select the appropriate size for your family. - Place the refrigerator away from the heat sources. - Do not put hot food in the refrigerator immediately. - Do not pack the refrigerator too full. - Defrost a freezer once a week. - Always clean a condenser. - Do not opent the refrigerator door often or keep it open. - Maintain a rubber gasket around the refrigerator door. Water heater - Choose the right size for your family. - Do not adjust the temperature too high. - Turn off the valves in order to keep water hot. - Not recommended for use the water heater in the summer. - Turn off the valve and faucet after showering. Air conditioning - Install the insulation in the ceiling of the air conditioned room. - Choose the right size of air conditioning for you room. - Select the air conditioning that has a quality assurance and energy efficiency. - Set the air conditioning temperature based on the season - Maintain and clean the components of the air conditioning. - Always keep doors and windows closed. - Turn on a ventilation fan when necessary. - Turn off the air conditioning about 2-3 minutes before leaving the room.

367 Washing machine - Choose the washing machine that suits the amount of laundry you do per load. - Sun-dry your clothes instead of using the clothes dryer. - Read the instruction manual first. 8. Safety and accidents from electrician jobs 1) Test or measure the electrical wiring to check the current with the electrical tools before opreation. 2) The electricians working on the electrical device while they are shut down or have power supply cut off have to connect the earth ground to the devices all time. 3) One end of the ground connection is required to connect the earth first, then connect the other end to the devices. 4) In case of uncertainty to touch the low voltage devices. Check them with the electrical test instruments. 5) Touching the electrical devices will use the correct tools and procedures only. 6) The electrical equipment and tools, like pliers or screwdrivers, must have two layers of good insulation. 7) While performing the operation, it must be certain that there are not any parts of body or the using tools incautiously contacting the parts of devices with current flowing. 8) The key locking switches, hanging the sign says no turn off switch controll, till unlocking the key or removing the sign shall always be done by the same person. 9) In order to climbing and working with the electrical devices in the high level, the electricians must wear a safety belts or straps. Otherwise, if there are no safety belts, they can use a thick rope hooked the structure or any parts of the buildings. 10) In the electricity operation, if it is possible, there should have an assistant. 8.1 Cautions for general working with electricity - When the outlet box is damaged, it should be replaced and repaired immerdiately. - Keep an area near the swtich clean. - Keep checking the switch control panel or the elctronic control unit to have no copper dust or any metal. Do not take the parts, such as fuses, out of the unit.

368 - Use fuses for a particular installtion. Before changing, shut down the switch. (Become an open circuit) - Do not use the switch lid made of flammable substances. - Each switch shall have a sign showing details as follows; * Use DC or AC * Potential diferrence (Voltage) * Electric current * Electrical instruments connected to the switch * A person’s who is in charge name - Shut down the switch to become an open circuit when the machine is required the detection or maintenance and hang a sign says ‚Under Maintenance‛. Before starting a closed circuit, it must be certain that everything is going well and gets signal approval. Moreover, before starting the machine, check for any blockages. - Giving the signals to be swtiched on or off shall be done by cautious. - Do not turn on or off the switches with wet hands. - Switch to be a closed circuit must be certainly done with the correct signal. - Screw to hold the wire tightly. - Do not use the damaged electrical equipment due to the accident. 8.2 The cautions in performing electrical work. - Do not pull the wire by the cable. - Do not use the damaged electrical equipment and tools. - Do not use the damaged plug. - Do not connect the output too overloaded. - Do not use the wrong plug in the wrong circuit. - Do not repair the eletrical equipment without knowledge.

369 8.3 Safety for electricians Attiring - A proper uniform for operating a machine is a one-piece garment with sleeves and legs in well-conditioned. The torn uniform shall not be used as the ripped parts can be stuck in machinery. - Do all buttons up. - Do not wear any accessories such as neacklaces, wrist watches, or rings. - Wear boots and shoes in order to protect a piece of matel pricked. - Wear safety eyewear in order to protect their eyes from a piece of metal such as metal cutting or light from welding - Wear a safety helmet. - Keep hair short or wear a safety helmet. - Wear ear protection in the excessive noise at work. 9. The good management and services Good services is the intention and attempt to provide services to customers. The levels of services are divided as follows; Level 1 Provide satisfactory customer service - Provide friendly service. - Provide precise information to curtomers. - Inform customers the progress of service procedures. - Coordinate interaction with customers continually and quickly. Level 2 Provide solutions to customers - Help customers solve problems or offer solutions to them as quickly as possible. - Satisfied customers and improve for better serivces.

370 Level 3 Provide service beyond expectation in spite of time or attempt. - Give customers more time in order to help them solve problems. - Offer the ways in which customers can maximize their benefits. Level 4 Understand and meet customer needs - Try to understand customer need in order to serve their needs. - Give helpful advice to customers in order to meet their needs. Level 5 Provide truly benefit services to customers - Think of customers’ long-term benefits. - Serve as a trusted consultant to help customers reach their satisfied decision. - Offer the different opinions or approaches to customers based on the necessity, problems, opportunities for customers’ truly benefits.

371 10. Science project to career path An electrician is an all time important profession and necessary for technology and society. The electricians must specialize in the field and be creative apart from installing and reparing electrical appliances. They can creat home appliances in order to make human life more convenient. Therefore, this profession can serve both services and businesses. You can apply the knowledge from the electricity science project to top up to various careers such as the lamp creations for decoration, the reading lamp creations, and the creation of the simple flood warning machine etc. Example 1 The lamp creation for decoration Materials Cost about 30 Baht 1. On-Off switch Cost about 79 Baht 2. Long florescent lamp 3. 61 CDs Reuse 4. 1.8 meter length of wire Cost about 30 Baht Directions for making a lamp from CDs Directions for making a lamp from CDs. No one would believe that we can turn scratched CDs to a classy lamp. Isn’t it interesting? Check this out how to make a splendid lamp with the cost of 139 Baht.

372 Lamp Remove the lighting components to use only a switch and a bulb for placing them to the roud wood base of the lamp. Measure where to place a switch and a bulb.

373 Cut the 3/8 inch plywood into 18 pieces of a round shape which have the same size as a CD. The pieces of cut plywood board Apply the hot glue and press it tightly. Leave it to dry for 20 minutes.

374 Use the drill to cut through the middle for placing a bulb. Drill two holes for a wire and a switch. Place a bulb in a hole.

375 Put a switch and a wire in the holes. Cut a hole in the middle of CDs. Make them wide enough to fit a bulb inside.

376 Cut a hole as shown in the figure above. Take a pair of CDs. Turn the shiny parts out. Then, apply the hot glue and leave them to dry. Drill 3 holes for placing long knots as holders as shown in the figure. Put CDs as the first row. Then, place the rings to bear as a row and leave a space for light spreading out. Follow this instructions until the last row. Apply the hot glue on 4 CDs and press them firmly. Use them as a lid. Change a bulb by loosening knots and replace a new bulb.

377 Turn the light as shown in the figure above. Source: http://www.yousaytoo.com/tensionnot/how-to-make-a-cool-cd-lamp/4877

378 Example 2 The creation of The simple flood warning machine Materials Cost about 100-150 Baht 1. A switch and a wireless electric doorbell ring Reuse 2. Pieces of foam Reuse 3. Plastic bags Directions 1. Buy a wireless electric doorbell ring from the department store (Price about 100-150 Baht). Select the continuously ringing doorbell that can wake you up. (Some types when pressing are ring once a time) 2. Collect the materials as follows; a short plastic basket, foam boards, water-resistant zipper bag, tape, double-sided tape, and brick or rock. 3. Apply double-sided tape on a doorbell switch to lift up the switch (Do not peel off the backings). Then, put it in a water-resistant zipper bag.

379 4. Cut the foam board to make it slightly smaller comparing to a basket. Place a zipper bag, with a doorbell ring inside, in the center of the foam board. Then, stick tape on the foam board. 5. Place the foam board in the anticipated area to be flooded such as the gateway. Cover the foam board with a basket and put a rock or a brick on a basket (a range of the doorbell signal is about 100 meters from the terminal). 6. Plug the doorbell terminal in a house.

380 7. When the area is flooded, the foam board will float and a switch will be pressed by a basket of which has a rock or a brick on top. Result to the alarmn signal. Source: http://www.oknation.net/blog/print.php?id=653105 11. Electrical vocabularies All electricians must understand definitions of general electric vocabularies for ordering materials and reading the material information from manufacturers efficiently. Both manufacturers and customers must be familiar with the electric vocabularies. Hence, you shall comprehensively study each definition of vocabularies and look up these vocabularies when necessary. Furthermore, there is more information of definitions in the appendix. Energy: The ability to do work. Horsepower: The unit used to measure the working machinery like motors and engines. HP is used as a symbol. Generally, the power output from an electric motor is measured in horsepower. Electricity: The movement of electrons flows through a conductor. Conductor: Matter that allows the current flowing through itself easily. Electrical conductance: The ability for electricty to flow a certain path. Electrical insulator: A material whose property resist the flow of electrical current. It may say that a matter opposes the movement of electrons. Magnetism: One property of matter produces fields that attract or repel magnets. Polarity: A property of electrical charges exhibited results in partial positve and negative electrical charges. Electromagnet: A conductive coil exhibits magnetic properties when electricity is passed through the coil.

381 Primary winding: It is a transformer winding connected to the power supply and receives the energy which is the input voltage source. Secondary winding: It is a transformer winding connected to the load. The energy is received by electromagnetic induction from the primary widing to the load that is called the output voltage. Electric power: It is the rate at which electric energy is used per unit time. Watt: The watt is a unit of power which is represented by the letter W. Each electrical appliances have the wattage labelled on them to tell the power, for example, 1,000 Watt light bulb, or 1,000 Watt toaster. Kilowatt: Kilowatt is unit of energy equal to 1,000 Watts. KW stands for kilowatts. There are several values of the electric load leading to the high watts. Therfore, to reduce the difiiculty with data recording, it is commonly used KW instead. Moreover, there is a larger unit than KW that is megawatt which is equal to 1,000 KW, or 1 MW in short. Kilowatt-hour: A unit of energy equivalent to one kilowatt of power expended for one hour of time. The abbreviation for kilowatt-hour is KWH. Usually, the amount of electric energy consumed by a residence is measured by an electricity meter which is measured in kilowatt-hours, also knows as unit. Then, the electricity bill is calculated by multiplying the unit rate by the units consumed. Alternating current: Electrical system is in which the flow of electrons periodically reverses direction. The abbreviation is AC. An alternating current is commonly used as electrical system in residences, buildings, and factories. Direct current: Electrical system is in which electrons move in one direction constantly and continuously. The most common use is battery chargers, dry cells, automotive batteries etc. The abbreviation of a direct circuit is DC. Electrical Circuit: An electrical circuit is a path connected together in which current flow. Series circuit: An electrical circuit has only one path for the current to flow from the power supply through a circuit to the other end of the power supply. Besides, there are devices in a circuit such as fuses, switches, circuit breakers connected in series in order to prevent and control a circuit.

382 Parallel circuit: An electrical circuit has two or more paths for the current to flow through. In addition, there are devices, like plugs or light bulbs connected in parallel. The advantage of this circuit is that if any devices break down, the other devices in a parallel circuit can still be working which is opposite to a series circuit. As shown in figure 2. Figure shows a parallel circuit. Open circuit: An electrical circuit in which the normal path of current has been interupted or disconnected resulting in no current flowing. Short circuit: An electrical circuit that allows current to travel along an unintended path due to a faullty or accident connection between two points of difference potential which an excessive current can flow through. Ampere: Ampere is a measurement unit of the amount of electrical charge passing through a conductor. The SI unit symbol is A or amp. Ampere is a unit that identifies a miximum allowable current of devices such as 15 amp plugs, 30 amp fuses. Hertz: Hertz is the unit of frequency defiened as the number of cycles per second. The movement of electrons flows in one direction and returns to the power supply. Then the electrons flow out of the power supply in one direction and return. The flow of electrons is in the reverse direction (in other words called moving back and forth) called 1 cycle. The electric power frenquency in Thailand is 50 Hertz. The SI unit symbol is HZ. Ohm: Ohm is the unit of electrical resistance. The symbol is Ω. The ohm of resistance will limit the flow of current. The resistance serves as a worker or an interrupter. It can work while it is used as the insulation or circuit controller, for example, electrical tapes, plug socket covers made of plastic which prevent accidents to the users of electricity. Additionaly, the rheostat, a variable resistor, is used to vary the brightness of light bulbs. However, it will interrupt a circuit when a small long wire is used or there is rusting on the surfaces of conductors which lead to the resistivity increase and give off heat together with the power of conducting wire lost.

383 Ohm’s law: Ohm’s law states the relationship between voltage, current, and resistance in an electrical circuit. The law says that current (I) is directly proportional to voltage (E) and inversely proportional to resistance (R). The formula is I = E/R. Volt: Volt is a unit for electric potential difference which is the force that makes electron move within a conductor. The voltage is abbreviated in V, E or EFM. The most common use is E and EFM represented the voltage produced by the electric charge movement or the electromotive force (the other definitions of volt). Like ampere, the voltage identifies a miximum allowable current of devices lablled on electrical devices for using them safely such as 220 Volt electric motors, 110 Volt hair dryers. It is important to use the proper voltage match to the devices as identification only. Ammeter: An ammeter is a measuring instrument used to measure the electric current in a circuit. Normally, this instrument is connected in series to the circuit in which is measured. However, there is a particular type of device which is not to be connected in series to the circuit. Ohmmeter: An ohmmeter is an electrical instrument that measures electrical resistance. While using an ommeter, there must be no power distribution from the power supply in the circuit. Voltmeter: A voltmeter is an instrument used for measuring electrical potential difference. Multimeter: A multimeter is an electronic measuring instrument that combines several measurement functions which are able to measure voltage and resistance in one unit. National Electrical Code: The National Electrical Code (NEC) is an adoptable standard for the safe installation of electrical equipment. Although a load of contents are introduced, the NEC handbook has no objective for teaching or being used by an untrained person. In Thailand, there are these handbooks provided in several places, like the handbooks of the Metropolitan Electricity Authority, the national energy, and the Regional Electric Power whose principles and regulations are mostly similar to the NEC. Circuit breaker: A circuit breaker is a protective device used to limit the maximum current in a circuit. When there is an over-current, the circuit breaker will open the circuit for not allowing the current flowing through another circuit until the circuit breaker is reset. At present, the circuit breaker are used more widely than fuses. Due to instantly reseting a circuit breaker

384 while fuses are required to replace the new ones, especially in a three-phase power system. If a fuse has brown, there will be two-phase of power left which leads to overheating or fire in a three- phase electrical motor. The detection method of a circuit breaker is to generate a magnetic field. When the strength of the electric current increases, the field will pull on a lever in the breaker. Some types of a circuit breaker have an overcurrent protective device relying on the current flowing through the bimetallic strip (Bimetallic is metal which expands in the high temperature and shrinks in the low temperature.) When the strength of the current increases, the heat increases as well. The bimetallic will expand itself to trip the switch of circuit breaker. The abbreviation of a circuit breaker is CB. Fuse: A fuse is an overcurrent protective device. When the current exceeds the limit, a fuse is overheated until it melts, then the circuit will open. Fuses must be connected in series to a circuit. Transformer: A transformer is an electrical device that transfers voltage reversely in order to match the voltage of an electrical device, for instance, there is a 110 Volt washing machine, but the voltage is 220 Volts. A transformer will be used to convert power from 220 Volts to 110 Volts, then the washing machine can be used. Besides, the transformer is commonly used with an intercom and a doorbell etc. Phase: A phase refers to types of an electrical system including a single-phase two-wire system and a three-phase four-wire system. A single-phase two-wire system is used in homes. In addition, a three-phase four-wire system is widely used in industries or large-scale businesses.

385 References Electicity Generating Authority of Thailand. (2008). Electrical system: Home wiring on floating walls. Bangkok. ------------. (2008). Electrical system: Conduit wiring in buildings. Bangkok. Jinda Pattharaphong and Atchariya Thongpong. (2008). Science learning media and content for secondary school in non-formal and informal education. Edition 3 Bangkok. p. 221-223. Bancha Sangthawee et al. (2007). Learning media for non-formal and informal education (NFE.) science SC 20 for secondary school. Wattanaphanit Publishing. Co.,Ltd. Bangkok. p. 241. Sarawut Yarnyut. (2004). Fundamental learning content of stage 3 for secondary school career and technology for technician. Mac Education Co., Ltd. p. 59-62. Office of NFE. (2004). Distance education workbook of career development class Code CD 20 for secondary school. The printing office of the express transportation organization of Thailand, Bangkok. p. 70, 79-81. ------------. (2010). Fundamental workbook for science subject PW. 11001 out of school education course for fundamental level B.E. 2551. Edition 1/2010. Ake Pim Thai Co., Ltd. Bangkok. p. 159-160. Suchart Wongsuwan. (2003). Learning for the 21st century Learning method that learners build their own knowledge in the workshop documentation for the development of learning process in integration. Hatyai Wittayalai Sombun Kunkanya School, Songkhla.

386 Appendix 1. The method for the science potential development for career To make a living is greatly important to the human existence. Careers not only serve our needs in the economic affairs, but also meet our other needs such as society and thoughts etc. To choose a career has an effect on your life. If a career is suitable for you, there will be a tendency to succeed in your career. On the other hand, if a job is not suitable for you, there will be a chance of failure. The course of five career groups is determined as a guideline as follows;

The table of the method of analysis for the Types of Job Description Careers 1. Agriculture 1. The agriculture refers to farming such as rice cultivation, gardening, an crop farming etc. 2. Livestock are domesticated animals raised in an agricultural setting lik cattle, pigs, or poultry etc. 3. Fishery is engaged in fishing such as raising and harvesting fish etc. 4. Forestry means making a living from the forest such as industrial fores plantations, and transforming forest products etc.

387 e science potential development for career Content Knowledge Relevant Jobs nd 1. The scientific method and science 1. Livestock; for example, careers project are applied to the technology for in livestock industries such as ke life. raising Thai local chickens, pigs, 2. Living things and environment are beef cattle, dairy cattle, honeybees, classified into living things, ecosystem, goats, frogs, mussels on suspended st natural resources, environment, ropes, oysters, silkworms, grouper preservation of local knowledge, and fish in offshore pens, catfish, Thai biotechnology. carp, muscovy ducks etc. 3. Energy in everyday life and energy 2. Crop farming and gardening conservation. 3. Rice cultivation. The example of 4. Astronomy for life; the relationship farming, for instance, sugar can between the sun, earth, and moon; farming, growing fingerroot, phenomena. pomelo farming, mango farms, mangoesteen farms, durian farms,

Types of Job Description Careers 2. Industry 1. Careers in agricultural industries like dairy farming, hydroponics, cann longan manufacturers, and agroprocessing industries etc. 2. Careers in finished goods industries such as electrical appliance factori furniture manufacturing factories, motorcycle manufacturers etc. 3. Careers in material industries such as rubber latex factories and palm o factories. 4. Careers in manufacturing industries like synthetic fiber factories, hot ro and cold rolled steel mills. 5. Careers in petroleum industries such as oil drilling and exploration, oil refining plants etc. 6. Careers in machinery industries, for instance, air conditioning compres manufacturers, water pump manufacturers, small engine manufacturers, a motorcycle assembly plants etc. 7. Careers in automotive industries such as automotive assembly plants, a body assembly plants etc.

388 Content Knowledge Relevant Jobs jasmine farms, flower gardens, vegetable gardening etc. ned 1. The scientific method and science 1. Manufacturing the project are applied to the technology for transformation of industrial ies, life. products or handicraft household 2. Living things and environment are products. oil classified into living things, ecosystem, 2. Manufacturing products that are natural resources and environment, spare parts, electrical equipment olled preservation of local knowledge, and and maintenance. biotechnology. 3. Manufacturing household l 3. Substance of life, element, compound, products such as vegetable oil, solution, substance and product in life, palm oil etc. ssor synthetic substance, the effects of 4. Manufacturing bedding products and substance and product on environment. and fabric dolls. 4. Force and energy for life, energy 5. Manufacturing plastic goods, auto conservation, and alternative energy. detergents, water bottles etc. 6. Take the product processing

Types of Job Description Careers

Content Knowledge 389 Relevant Jobs over; for instance, manufacturing products of household industries such as weaving silk sarongs with part of skirtlive dress, fabric of dyeing silk thread, weaving silk on hand looms, mat weaving, canvas sewing, producing latex sheeting, making batik t-shirts, making hair accessories, making crafty things from mulberry paper, making souvenirs and keepsakes, making flower garlands to flower shops, sewing ready-made garment, making charcoal, making Thai fermented sausages, and making Chinese steamed dumplings etc.

3. Commerce Commerce and administration in all related businesses include retail trade wholesale trade, exports, banking, insurance, and artificial intelligence in computer businesses for commerce.

390 e, 1. The scientific method and science 1. Merchandising goods, n project are applied in life. accounting. 2. Living things and environment are 2. Services classified into living things, ecosystem, Manufacturing ready-made food natural resources and environment, and products such as selling souvenirs, conservation. selling local produce, selling 3. Energy in everyday life and energy noodles and foods, selling conservation. miscellaneous items, selling 4. Technology. groceries, selling finished goods, selling snacks, fruits, selling foods and beverages, selling lottery tickets, selling dolls, selling deep- fried dough sticks, and selling fresh seafood. 3. Working as a middleman; for example, commission merchants, customer services, per merchandise, selling airline tickets,

4.Creativity Creative professions consist of 1) Heritage or cultural heritage is an industrial group related to history, archaeology, culture, tradition, belief, and social conditions etc. It is divid into two groups; first group is the traditional cultural expression, such as and crafts and festivals etc. and the second group is the cultural sites including archaeological sites, museums, libraries, and exhibitions etc. 2) Arts are the creative industries based on arts and cultures which consis 2 groups; Visual arts include drawing, sculptures, photographs, and antiq etc. The other group is performing arts, for instance, music shows, plays, dancing, operas, circuses, and puppet plays etc.

391 and selling furniture. 4. Medical supplies such as selling medicines, selling cosmetics, selling gold and silver jewelry, selling fresh flowers, selling LPG, direct-sales cosmetics, selling agricultural products, industrial products by their own manufacturers etc. 1. The scientific method and science Divided into 8 groups; project are applied to the technology for 1) Crafts ded life. 2) Design arts 2. Living things and environment are 3) Fashion classified into living things, ecosystem, 4) Film & Video natural resources and environment and 5) Broadcasting st of conservation. 6) Performing Arts ques 3. Substance of life, element, compound, 7)Advertising and Publishing solution, substance and product in life, 8) Architecture synthetic substance, the effects of

3) Media is a creative group which communicates to the public. Media is divided into 2 groups that are publishing and printed media such as books newspapers, and printed materials etc., and audiovisual like T.V. movies, radios, other broadcasts etc. 5. Service and 4) Functional creation is a group of products and services that meet custo Administration needs consisting of 3 groups; Design such as interior design, graphic, fash jewelries, and toys etc.; New media includes software, video games, digit content etc.; and Creative services, for example, architectural services, advertisements, culture and recreation, research and development, other services related to digital and creativity etc. Service sector is a profession in which entrepreneurs provide service to facilitate customers. The quality of services is customer satisfaction. Inco is a reward which is earned from the services. Working in service sector i not required much investment comparing to the investment of product manufacturing. The process is simple. However, a service provider must possess knowledge and has experience or skills.

392 substance and product on environment. s, 4. Force and energy for life, energy , conservation, and alternative energy. 5. Energy in everyday life and energy conservation. omer hion, tal 1. The scientific method and science The example of service in careers ome project are applied to the technology for Repairman such as motorcycle is life. mechanics, automotive mechanics, 2. Living things and environment are coloring page auto mechanics, classified into living things, ecosystem, repairman for car seat cushions, natural resources and environment and television repairman, radio conservation. technicians, electrical technicians,



393 3. Substance of life, element, compound, welding mechanics, and roof solution, substance and product in life, mechanics. synthetic substance, the effects of Beauty group such as tailors, substance and product on environment. beauticians-make up artists, 4. Force and energy for life, energy hairdressers, and barbers. conservation, alternative energy, electric Artisans, portrait artists, artists in energy, light energy, sound energy, advertising posters, constructors, energy in everyday life and energy florists both fresh and dry flowers. conservation. General workers such as babysitters, launderers, video rental shops, book rental shops, bungalows, dormitory, beach scooters, car rental, driving taxi, motorcycle taxi, truck rental, took- took, photocopying documents, hiring for typing documents, musician restaurants, engraving oysters, chopping lemongrass for factories, construction workers etc.