Chapter 1: ELECTRICAL SAFETY Answers to Chapter Review REVIEW QUESTIONS 1. True or False: A heating and air conditioning service technician can usually troubleshoot heating and air-conditioning systems without the voltage being supplied to the equipment. False 2. What is a live electrical circuit? a circuit that is being supplied with electrical potential (voltage) 3. Which of the following voltages will a refrigeration, heating, and air-conditioning technician come in contact with in the industry? d. all of the above 4. Electrical shock occurs when a person _________. c. becomes part of an electric circuit 5. What are the important elements of electrical safety when working around live circuits? • Respect electricity. • Do not be careless. • Make sure electrical power is disconnected from circuits that are being worked on if possible. • Learn the safety rules in section 1.7 of this chapter. 6. Which of the following conditions is the most dangerous and likely to cause serious injury? d. The technician touches a live conductor with his right hand and touches a ground with his left hand. 7. Which of the following is the standard by which electrical installations are measured in the United States? a. National Electrical Code ® 8. True or False: A current flow of 0.1 ampere or less could be fatal. True 1 Copyright © 2019 Cengage Learning 9. What type of ladder should the technician use on the job? e. both b and c 10. What precautions should be taken when you see a coworker receiving an electrical shock? Never touch a person who is receiving an electrical shock. 11. True or False: It is recommended that at least one person on a truck know CPR. True 12. True or False: The correct fuse size for an electrical circuit is one that is sized twice as large as needed for circuit protection. False 13. What is the difference between a two-prong plug and a three-prong plug? A three-prong plug has a ground, while a two-prong plug does not. 14. Which prong on a three-prong plug is the ground? c. the center semicircular prong 15. True or False: A grounding adapter does no good if it is not connected to an electrical ground. True 16. An electrical device that will open an electrical circuit, preventing current flow to the circuit if a small leak to ground is detected, is called a _________. a. GFCI 17. True or False: Receptacles used on the job site should be protected with a GFCI. True 18. What precautions should you use when working in an area with a large number of people and you must disconnect the power from an appliance you are working on? Lock out circuit being serviced. 19. What is the difference between a fuse and a circuit breaker? A fuse will have to be replaced when an overload occurs, while a circuit breaker will only have to be reset. 2 Copyright © 2019 Cengage Learning 20. List at least five electrical safety rules that should be followed by refrigeration, heating, and air-conditioning technicians. Answer should contain five rules from section 1.7 (Electrical Safety Guidelines) 3 Copyright © 2019 Cengage Learning Chapter 2: BASIC ELECTRICITY Answers to Chapter Review REVIEW QUESTIONS 1. All physical objects are composed of __________. b. matter 2. What is an atom? An atom is the smallest particle of an element that can exist alone or in combination. 3. Which of the following is a part of the atom? d. all of the above 4. What is static electricity? a flow of electrons by permanently displacing an electron from an atom 5. Name three ways electricity can be produced. • friction • chemical • magnetic (induction) 6. What part do protons and electrons play in the production of electricity? The charge of an atom is determined by the number of electrons (negatively charged particles) and the protons (positively charged particles) in the atom. When there is an unbalance in the number of electrons and protons in an atom, electrons will flow to the atom in an attempt to balance the charge. 7. Which of the following is the simplest atom that exists? b. hydrogen 8. What are the four most important characteristics of an electric circuit? • pressure (voltage) • current (amperage) • resistance (ohms) • power (watts) 9. What is electromotive force? electrical pressure (voltage) 4 Copyright © 2019 Cengage Learning 10. Electromotive force is commonly measured in __________. c. volts 11. What is current? Current is the quantity of electrons flowing in an electrical circuit. 12. How is current measured? a. amperes 13. What is resistance? the opposition to the flow of electrons in an electrical circuit 14. How is resistance commonly measured? b. ohms 15. What is electrical power? Electrical power is the rate at which electrons do work. 16. How is electrical power commonly measured? d. watts 17. Where do electrons exist in an atom, and what is their charge? Electrons orbit around the nucleus of the atom in shells and their charge is negative. 18. True or False: All atoms tend to lose electrons. True 19. State the law of electric charges. like charges repel and unlike charges attract 20. What is a proton? Where does it normally exist in an atom, and what is its charge? A proton is a positively charged particle of an atom and exists in the nucleus. 21. Describe briefly the method a dry cell battery uses to produce voltage. A dry cell battery produces an electron flow by a chemical reaction that causes a transfer of electrons between the two electrodes. 22. What is a conductor? an element that conducts electricity 5 Copyright © 2019 Cengage Learning 23. Which of the following is the best conductor? c. copper 24. What is an insulator? an element that retards the flow of electrons 25. Which of the following is the best insulator? b. thermoplastic 26. Why do metals make the best conductors? The electrons of most metals are easily given up from the outer electron orbits of the atom. 27. How do electric utility companies charge customers for electricity? kilowatt hours 28. What is the meaning of SEER when used in conjunction with an air-conditioning unit? seasonal energy efficiency ratio 29. State Ohm’s law. Ohm’s law states that it will take 1 volt of electrical pressure to push 1 amp of electrical current flow through 1 ohm of resistance. 30. True or False: Ohm’s law applies to all types of electrical circuits. False 31. What is the ampere draw of a 5000-watt electric heater used on 120 volts? c. 50 ampere 32. What is the resistance of the heating element of an electric iron if the ampere draw is 8 amperes when 115 volts are applied? c. 14 ohms 33. What is the voltage of a small electric heater if the heater is drawing 12 amperes and has a resistance of 10 ohms? a. 120 volts 34. What is the Btu/hour output of an electric heater rated at 15 kilowatts? 6 Copyright © 2019 Cengage Learning b. 51,150 Btu/hour 35. What is the kilowatt output of an electric heater that has an ampere draw of 50 amperes if the voltage source is (a) 208 volts? (b) 240 volts? (a) 10.4 kW (b) 12 kW 7 Copyright © 2019 Cengage Learning Chapter 3: ELECTRIC CIRCUITS Answers to Chapter Review REVIEW QUESTIONS 1. What is a series circuit? An electrical circuit that has only one path for electron flow. 2. What is a control circuit? A control circuit is an electric circuit that controls some major load in the system. 3. Safety devices in an electrical circuit are connected in __________ with the load. series 4. How are series circuits used in air-conditioning equipment? Series circuits are used as control circuits. 5. Why are series circuits used for most control circuits? When switches are wired in series with a load; if any switch opens, then the circuit will be open and the load de-energized. This is important, especially with safety controls. 6. The current draw in a series circuit is __________. b. the same throughout the entire circuit 7. The voltage drop of a series circuit is __________. b. proportional to the resistance in that part of the circuit 8. How would switches used as safety devices be connected with respect to the loads they are protecting? series 9. Draw a series circuit with a thermostat, a low-pressure switch, and a high- pressure switch used as safety controls to protect a motor. 8 Copyright © 2019 Cengage Learning 10. Two identical 115-volt light bulbs connected in series with 240 volts would __________. c. burn correctly 11. Draw a circuit with four electric heaters ( ) in series. 12. What is a parallel circuit? An electrical circuit with more than one path of electron flow. 13. Parallel circuits are used in the air-conditioning industry to __________. a. supply the correct line voltage to several circuits 14. Why are parallel circuits used in the air-conditioning industry? to supply line voltage to all line voltage loads in equipment or a control circuit 15. True or False: The current draw of a parallel circuit is the sum of the current of each branch circuit. True 16. If three circuits are connected in parallel with a power supply of 30 volts, what would be the voltage supplied to each circuit? c. 30 volts 17. If two 115-volt loads were connected in parallel with 240 volts, they would __________. b. immediately burn out 18. What is a series-parallel circuit? a combination of series and parallel circuits 19.