(NEETS) MODULE 4
ELECTRICAL WIRING
1. Why has a "unit size" for conductors been established?
11. What factor(s) must be known to compute the resistance of a conductor?
A. To compare the size and resistance of one conductor with that of another another * B. To establish a uniform style for conductors C.To determine the requirements for conductors D.To ensure all conductors are interchangeable 2. What is the decimal equivalent of one (1) mil? A. 1.000 1.000 in. B. 0.100 0.100 in. C.0.010 in. D.0.001 in. * 3. If a conductor has a diameter of 1/4 inch, what is i ts diameter in mils? A. B. C. D.
250.0 mil * 25.0 mil 2.50 mil 0.250 mil
4. What is the definition of a mil foot? A. A conductor .001 foot in length with a diameter of .001 millimeter B. A conductor 1 foot in length with a diameter of .001 foot C.A conductor 1 foot in length with a diameter of 1 mil * D.A conductor .001 foot in length with a diameter of .001 inch
5. A square mil is defined as the area of a square, the sides of which are each equal in length to what dimension? A. 1 mil-foot B. 1 mil * C.1.0 inch D. .001 mil
7. A circular mil is defined as the area of a circle having what dimension? A A A A
radius of 1 mil diameter diameter of 1 mil * circumference of 1 mil chord of 1 mil
8. If you have a 12-strand conductor and each strand has a radius (one-half the diameter) of 2/10 inch, what is the circular mil area of the conductor? A. B. C. D.
A. The length of the conductor B. The cross-sectional area of the conductor C.The specific resistance of the substance of the conductor D.Each of the above * 12. 13. When a wire gauge is used to determine the size of a wire, the measurement should be made in what part of the gauge? A. In the slot * B. In the semicircular opening C.Either 1 or 2 above, depending on wire size
14. Which of the following factors is used to determine the current rating of a wire? I. Conductor size II. Material of conductor III. Load requirement requirement IV. Wire ductility V. Type of of insulation insulation VI. Location of wire in circuit circuit VII. Source voltage A. B. C. D.
II, III, III, V, and VII I, IV, V, and VII II, IV, V, and VI I, II, V, and VI *
15. What types of insulation are best suited for use in a hightemperature environment? A. Cotton, Cotton, polytetrafluoroethylene, and oiled paper B. FEP, silicone rubber, and extruded polytetrafluoroethylene polytetrafluoroethylene * C. Oiled paper, FEP, and r ubber D. Rubber. polytetrafluoroethylene, and silk 16. What is the "ambient" temperature of a conductor?
6. Figure
A. B. C. D.
ASSIGNMENT 1
1,920,000 cir. mil * 57,680 cir. mil 48,000 cir. mil mil 2,400 cir. mil
9. What If you have a 12-strand conductor and e ach strand has a radius (one-half the diameter) of 2/10 inch, what is the square mil area of the conductor? A. 244,344,097 sq. mil B. 1,507,965 sq. mil * C.61,115 sq. mil D.45,239 sq. mil 10. What is the definition of specific resistance? A. The resistance of a length of conductor, at a given temperature, to voltage B. The resistance of a cross-sectional area of a conductor, at a given temperature, to the flow of current C.The resistance of a unit volume of a substance to the flow of current expressed in ohms *
A. It is the normal temperature of a conductor through which current is flowing B. It is the heat generated by external sources and affecting a conductor’s temperature * C.It is the maximum heat a conductor can withstand according to its current rating D.It is the temperature at which the insulation of a conductor begins to break down 17. Which Which of the following metals is the best conductor of current? A. B. C. D.
Aluminum Copper Silver * Manganin
18. When electricity is carried over long distances, which of the following are advantages for using aluminum as the conductor as opposed to copper? I. II. III. IV. V. VI. VII. VIII. IX.
High cost High ductility High tensile strength Easily soldered Very light in weight Difficult to solder Reduces corona Generally uninsulated High conductivity conductivity
A. II and III B. IV and V C.III and IX D.V and VII * 19. Which Which of the following are advantages for using copper as the conductor as opposed to aluminum?
1
(NEETS) MODULE 4 I. II. III. IV. V. VI. VII. VIII. IX. A. B. C. D.
ELECTRICAL WIRING
High cost High ductility High tensile strength Easily soldered Very light in weight Difficult to solder Reduces corona Generally uninsulated High conductivity II, IV, and IX * III, V, and VII II, V, and VIII I, VI, and IX
Copper Aluminum Manganin * Silver
A. 0.32 ohm B. 9.61 ohms C. 65.39 ohms D. 84.61 ohms * 22. What definition best describes an i nsulating material? very high resistance * very low resistance very high conductivity very low dielectric strength
23. The dielectric strength of an insulating material is a measurement of the material's ability to resist electrostatic stress caused by what factor? A. Resistance B. Current C. Voltage * D. Chafing or friction
24. Insulation resistance can best be defined as the ability of an insulating material to resist what action? A. Current leakage * B. Electrostatic stress C. Breakdown by voltage D. External factors acting upon the conductor 25. For a material to be a good insulator, what two properties are most important? A. High dielectric strength and low insulation resistance B. High dielectric strength and hi gh insulation resistance * C. Low dielectric strength and high insulation resistance D. Low dielectric strength and low insulation resistance 26. When rubber is used as the insulating material over a copper conductor, why is a thin coating of tin used between the two materials? A. To decrease the electrostatic stress B. To increase the insulation resistance of the rubber C. To prevent a chemical action from taking place between the copper and rubber * D. To reduce the amount of insulating material required. 27. What is the NEC for a rubber heat resistance compound? A. RHH * B. RWH
28. Latex rubber is a high-grade compound consisting of what percentage of unmilled grainless rubber? A. 70% B. 80% C.90% * D.95%
A. B. C. D.
Very high to high High to medium Medium to low * Low to very low
30. When dealing with NEC type designators for thermoplastics, the letter "W" stands for what type of insulation? A. B. C. D.
21. If a 75-ohm sample of copper wire at 0ºC is heated to 30ºC, what is the approximate total resistance? (The temperature coefficient of resistance of copper at 0ºC is 0.00427).
A. A material that has a B. A material that has a C. A material that has a D. A material that has a
C. RTW D. RWT
29. Plastic insulation is normally used for what levels of voltage?
20. Because its resistance changes very little with temperature changes, what conductor is best suited for use in measuring instruments? A. B. C. D.
ASSIGNMENT 1
Oil-resistant Moisture-resistant * Heat-resistant Asbestos
31. When you work on synthetic insulated wiring, what safety precaution must be observed? A. Wear protective goggles at all times B. Avoid breathing the vapors when the insulation is heated * C.Wear a dust mask in confined spaces D.Wear protective gloves if there are cuts or abrasions on your hands 32. What nonmetallic material is most commonly used to protect wires and cables? A. B. C. D.
Rubber Jute and asphalt covering Fibrous tape Fibrous braid *
33. What is the common name for woven covers? A. B. C. D.
Yarn Loom * Fibrous tape Unspun felted cotton
34. What percentage of tin is used in alloy lead sheathing? A. 6% B. 2% * C. 8% D. 4% 35. Why is the use of asbestos being discontinued as an insulating material in the Navy? A. B. C. D.
It breaks down rapidly with continued use It is not as effective as other types of insulation It has not proven suitable for a shipboard environment It poses a health hazard to personnel *
36. What happens to asbestos insulation when it gets wet? A. B. C. D.
Its insulation resistance becomes too high It emits dangerous fumes It acquires too great a dielectric strength It becomes a conductor *
37. What insulating materials are best suited for use with high voltage? A. B. C. D.
Thermoplastic and rubber Varnished cambric and oil impregnated paper * Teflon and silk Silk and cotton
38. What is the common name for enamel-insulated wire?
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(NEETS) MODULE 4
A. B. C. D.
ELECTRICAL WIRING
Winding wire Motor wire Magnet wire * Coil wire
39. What types of conductor protection are normally used for shipboard wiring? A. Wire braid armor and nonmagnetic steel tape * B. Lead cable and Jute C. Jute and nonmagnetic steel tape D. Lead sheathing and rubberized tape 40. What are the basic requirements for a splice or terminal connection? A. To be mechanically and electrically effective * B. To be pre-insulated and nonconductive C. To have minimum cost and maximum efficiency D. To have circuit continuity and minimum cost 41. The preferred method for removing insulation from most types of insulated wire is by using what tool? A. Razor blade B. Electrician’s pliers C. Wire stripper * D.Knife 42. When a wire is insulated with glass braid or asbestos and requires stripping, which of the following tools should NOT be used? A. Knife B. Rotary wire stripper C. Hand wire stripper D. Hot-blade wire stripper *
ASSIGNMENT 1 A. When a branch circuit is joined to a continuous wire (main wire) * B. When a W estern Union splice would be too bulky C.When a lighting fixture is joined to a branch circuit D.When a wire nut is used to complete the joint
49. Which of the following splices is NOT butted? A. Fixture joint B. Rattail joint C. Knotted tap joint * D.Western Union splice 50. Why is friction tape used over a splice? A. To provide a protective covering over the rubber tape * B. To provide maximum insulation to the splice C.To prevent shock when latex rubber is used D.To reduce the amount of rubber tape required 51. Why would you use a crimped terminal instead of a soldered terminal? A. Connections can be made more rapidly B. Less operator skill is required C.Connections are more uniform in construction D.Each of the above * 52. When non-insulated splices and terminal lugs are insulated, what types of insulation are most commonly used? A. Rubber tape and friction tape B. Spaghetti and h eat-shrinkable tubing * C.Spaghetti and friction tape D.Rubber tape and heat shrinkable tubing 53. When heat-shrinkable tubing is used, what is the maximum temperature to which the wire should be subjected?
43. What is the preferred tool to use to strip aluminum wire? A. Knife * B. Rotary wire stripper C. Hand wire stripper D. Hot-blade wire stripper 44. When a Western Union splice is used to connect two wires, why should the twisted ends of the wires be pressed down as close as possible to the straight portion of the wire? A. To increase the strength of the splice B. To prevent the wires from puncturing the tape covering * C. To minimize the resistance change in the circuit D. To increase the dielectric strength of the insulation 45. When multi-conductor cables are spliced, why are the splices staggered? A. B. C. D.
To prevent possible shorting between conductors To increase the strength of the individual splices To decrease insulated resistance To reduce the overall size of the joint *
A. 180ºF B. 220ºF C. 300ºF * D. 340ºF 54. When a large aluminum terminal lug or splice is installed, why is it NOT necessary to clean the aluminum wire? A. It is done automatically by the tubing B. The wire is cleaned by the abrasive compound in the l ug or splice * C.Oxide film does not form on aluminum D.The insulation used provides the necessary cleaning agent 55. When aluminum terminals lugs or splices are installed, which of the following tools is generally recommended for use? A. Pliers B. Power crimping tool * C.Hand crimping tool D.Vise grips
46. When is a rattail joint normally used? 56. Why is a lockwasher NOT used with an aluminum terminal? A. When a branch circuit is required and a junction box is used to join conduit * B. When a Western Union splice would be too bulky C. When asbestos or glass braid is used as insulation D. When the branch wire will be subjected to a heavy strain 47. If a fluorescent light is to be attached to a branch circuit, which of the following splices should normally be used? A. Staggered splice B. Knotted tap joint C. Western Union splice D. Fixture joint * 48. When is a knotted tap joint normally used?
A. The washer will reduce conductivity at the terminal B. The washer will gouge the lug and cause deterioration * C.The washer will set up a corrosive action between dissimilar metals D.The washer will increase resistance and heat causing eventual failure 57. The most common method of terminating and splicing wires is by using pre-insulated terminal lugs and splices. A. True * B. False 58. Which of the following is an advantage of using pre-insulated splices and terminal lugs?
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(NEETS) MODULE 4
ELECTRICAL WIRING
ASSIGNMENT 1
A. Heat shrinkable tubing is not required B. Spaghetti is not required C. They offer extra supporting strength to the wire insulation * D. Each of the above
59. Color codes are used on pre-insulated terminal lugs and splices to indicate what information? A. The resistance, in ohms, of the lugs and splices B. The style of crimping tool to be used C. The type of circuit in which they are to be used D. The wire sizes on which they are to be used *
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