qna for master electrician

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With respect to pulling wires into a conduit, it is usually specified that a certain percentage of the conduit area must be left unoccupied. The purpose of this requirement is to permit a. pulling in the wires without undue strain or abrasion b. pulling in additional wires later if needed c. pulling out the wires for replacement even if the insulation has swelled d. circulation of air so that the insulation will not be damaged by heat. When installing electric wiring it is essential that all conduits be a. concealed b. rigidly supported c. left exposed markers The internal diameter of inch electrical conduit is approximately a. 0.422 inch b. 0.5 inch c. 0.552 inch

2.

d.

given identifying

3.

d.

0.622 inch

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The most important reason for using a condulet-type fitting in preference to making a bend in a one-inch conduit run is to a. obtain a neater job b. cut down length of conduit needed c. avoid possible flattening of conduit when bending d. make wire pulling easier Electrical wires are run through conduit in order to a. increase the current carrying capacity of the wires b. protect the wires from damage c. decrease the cost of initial installation d. increase the break-down voltage of the wires When a conduit enters a knock-out in an outlet box, it should be provided with a a. locknut on the inside and a bushing on the outside b. bushing on the inside and a locknut on the outside c. bushing and a locknut on the outside d. bushing and a locknut on the inside The main reason for grounding conduit installation is to a. reduce leakage between wires b. prevent short circuits c. save wiring d. prevent conduit from becoming alive to ground The inside edge on the end of conduit is reamed after cutting mainly to a. aid in screwing on the bushing b. prevent injury to the wire c. make pulling the wire easier d. finish the end of the thread A conduit is to be run diagonally across a 6 foot by 8 foot room. If the ends of the conduit are to be one foot from the room corners, the conduit should be cut to a. 8 feet b. 9 feet c. 10 feet d. 12 feet

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10. To support conduit on a hollow tile wall, use a. through-bolts b. lag screws

c.

machine screws

d. toggle bolts

11. According to the national electrical code, a run of conduit between two outlet boxes should not contain more than four quarter-bends. The most likely reason for this limitation is that more bends will a. result in cracking the conduit b. makes the pulling of the wire too difficult c. increase the wire length unnecessarily d. not be possible in one standard length of conduit 12. Standard iron conduit comes in 10-foot lengths. The number of such lengths required for a run of 23 yards is a. 3 b. 4 c. 6 d. 7 13. Rigid conduit is generally secured to sheet metal outlet boxes by means of a. threadless couplings b. box connector c. locknuts and bushings d. conduit clamps 14. Checking a piece of rigid electrical conduit with a steel scale, you measure the inside diameter as 1 1/16 and the outside diameter as 1 5/16. The nominal size of this conduit is a. b. 1 c. 1 d. 1 15. Where galvanized steel conduit is used, the primary purpose of the galvanizing is to a. increase mechanical strength b. retard rusting c. provide a good surface for painting d. provide good electrical contact for grounding 16. When a number of rubber insulated wires are being pulled into a run of conduit having several sharp bends between the two pull boxes, the pulling is likely to be hard and the wires are subjected to considerable strain. For these reasons it is advisable in such a case to a. push the wires into the feed end of the conduit at the same time that pulling is being done b. pull in only one wire at a time c. use extra heavy grease d. pull the wires back a few inches after each forward pull to gain momentum 17. Rigid conduit must be so installed as to prevent the collection of water in it between outlets. In order to meet this requirement, the conduit should not have a a. low point between successive outlets b. high point between successive outlets c. low point at an outlet d. high point at an outlet 18. One advantage of cutting 1 rigid conduit with a hacksaw rather than with a 3-wheel pipe cutter is that a. the cut can be made with less exertion b. the pipe is not squeezed out of round c. less reaming is required after the cut d. no vise is needed 19. The National Electrical Code requires that conduit must be continuous from outlet to outlet, must be mechanically and electrically connected to all fittings, and must be suitably grounded. The reason for having the conduit electrically continuous and grounded is to a. provide metallic return conductor b. shield the wires inside the conduit from external magnetic fields c. make it easy to test wiring connections d. prevent electrical shock which might otherwise result from contact with the conduit

20. A conduit coupling is sometimes tightened by using a strap wrench rather that by using a Stillson wrench. The strap wrench is used when it is important to avoid a. crushing the conduit b. stripping the pipe threads c. bending the conduit d. damaging the outside finish 21. A standard pipe thread differs from a standard screw thread in that the pipe thread a. is tapered b. is deeper c. requires no lubrication when cutting d. has the same pitch for any diameter of pipe

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A good electrical insulator which will resist a very high temperature is a. bakelite b. enamel c. transformer oil

d.

mica

12. When skinning a small wire, the insulation should be penciled down rather than cut square to a. prevent the braid from fraying b. save time in making the splice c. decrease danger of nicking the wire d. allow more insulation in the splice 13. Asbestos is commonly used as the covering of electric wires in locations where there is likely to be high a. voltage b. temperature c. humidity d. current

14. Overloading insulated wire or cable for long periods of time is considered poor practice because it usually causes a. over expansion of the conductor b. the conductor to melt c. damage to the duct or conduit d. the insulation to deteriorate 15. Rubber insulation on an electrical conductor would most quickly be damaged by continuous contact with a. acid b. water c. oil d. alkali 16. In measuring to determine the size of a stranded insulated conductor, the proper place to use the wire gauge is on a. the insulation b. the outer covering c. the stranded conductor d. one strand of the conductor 17. The material which is least likely to be found in use as the outer covering of rubber insulated wires or cables is a. cotton b. varnished cambric c. lead d. neoprene 18. Circulating shaft currents through the bearings of a turbo-generator will cause pitting and deterioration of the bearing surface, these circulating currents are stopped by a. having an insulating pad under one generator pedestal b. the insulating property of the lubricating oil

c. d.

insulating the shaft from the machine frame having an insulating section in the shaft

19. The life of insulation used in electrical installations is directly affected by heat. Of the following, the electrical insulation which can least withstand heat is a. enamel b. rubber c. fiberglass d. mica 20. One advantage of rubber insulation is that it a. does not deteriorate with age b. is able to withstand high temperatures c. does not absorb much moisture d. is not damaged by oil 1. After a new series lighting circuit has been completely installed, but before any lamps are in place, a standard lamp bank is connected across the fuse clips with the fuse out, and the circuit switch is closed. Lamps are then screwed into the sockets of one series, one lamp at a time, starting at the ground end. If there is a ground on any series wire, the lamp bank will light when the a. first lamp is screwed in b. lamp on the low side of the ground is screwed in c. lamp on the high side of the ground is screwed in d. last lamp is screwed in The grounded leg of a lighting circuit is always connected to the shells of the lighting sockets to a. ground the circuit b. reduce the possibility of accidental shock c. simplify the wiring d. avoid burning out lamps Light fixtures suspended from chains should be wired so that the a. wires do not support the fixture b. wires help support the fixture c. chains have an insulated link d. chain is not grounded to prevent short-circuits Portable lamp cord is likely to have a. steel armor b. stranded wires

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3.

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c.

paper insulation

d.

number 8 wire

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A test lamp using an ordinary lamp bulb is commonly used to test a. for polarity of a d.c. power supply b. whether a power supply is a.c. or d.c. c. whether a circuit is overloaded d. for grounds on 120-volt circuits One advantage of D.C. lighting is a. the ease of locating a burnt out lamp b. the possibility of using five lamp clusters where necessary c. there is no necessity of providing a special lighting transformer d. one side of the circuit is grounded

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When testing a lighting circuit for grounds, the device which would be least useful is a. a lamp bank b. a megger c. an ammeter d. a voltmeter One advantage of using series circuits for street lighting is

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a. b. c. d. 9.

lower voltage circuit decreased copper requirements longer lamp life higher lamp efficiency

Five 120 volt lamps are placed in series across a 600 volt circuit and light normally. One of the lamps is then removed and replaced with a good plug fuse. Under these conditions the total illumination supplied by the remaining 4 lamps will be a. greater than for the lamps b. less than for the 5 lamps c. approximately the sam

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