With respect to pulling w wires ires into a conduit, it is usually specified that a certain 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 abrasion b. pulling in additional wires 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 n not ot be damaged by heat.
When in installing stalling electric wiring it is essential that a allll conduits be a. concealed b. rigidly supported c. left exposed markers
The internal diameter of ½ inch electrical conduit is approximately a. 0.422 inch b. 0.5 inch c. 0.552 inch
0.622 0.622 inc h
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 pulli ng easier 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 enters a knock-out in an outlet bo box, x, it should be provided with a a. locknut on the inside and a bushing on the outside b. bushin g on the inside a and nd a locknu t on the outsi de 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 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 cutting mainly to a. aid in screwing on the bushing b. prevent injury to the wire c. make pulling the wire easier d. fini sh the end of the thread
A conduit is to be rrun un diagonally across a 6 foot by 8 foot room. If the ends of tthe he conduit are 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
10. To support conduit on a hollow tile wall, use a. through-bolts b. lag screws
d. toggle bolts
11. According to the national electrical electrical code, a run of conduit between two outlet boxes should not contain more than than four quarter-bends. The most likely reason for this limitation is that more bends will a. result in cracking the conduit b. makes makes the pulling of the wire too difficult c. increase the wire length unnecessarily d. not be possible in one standard length of of con conduit duit 12. run Standard conduit comes in 10-foot lengt lengths. hs. The number of such lengths required for a of 23 iron 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 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. ¾” b. 1” c. 1 ¼” d. 1 ½” 15. Where galvanized st steel eel conduit is used, the primary pur purpose pose of the galvanizing is to a. increase mechanical strength b. retard rusti ng 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. strain. For these reasons it is advisable in such a case to a. push the wires into the feed end of the condui t 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 betwee between n 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 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 electrically connected to all fittings, and must be suitably grounded. The reason for having the conduit conduit electrically continuous and grounded is to a. provide metallic return conductor b. shield tthe he wires inside the conduit from external magnetic fields c. make it easy to test wiring connections d.
prevent prevent electrical 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 outsi de fini sh 21. A pipe thread differs from a standard screw thread in that the pipe thread a. standard is tapered b. is deeper c. requires no lubrication when cutting d. has the same pitch for any diameter of pipe
A good good electrical electrical insulator which will resist a very high temperature temperature is a. bakelite b. enamel c. transformer oil
12. When skinning a small wire, the insulation should be “penciled down” rather than cut sq square uare to a. prevent the braid from fraying b. save time in making the splice c. decrease decrease danger of nicki ng 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.
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 insulatio n 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 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 by a. b.
having an an insulating pad pad under one generator pedestal the insulating property of the lubricating oil
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 insulation which can least withstand heat is a. enamel c. fiberglass d. mica b. rubber 20. One advantage of rubber insulation is that it a. b. c. d.
does withtemperatures age is ablenot to deteriorate withstand high does not absorb much moisture is not damaged by oil
After a new series lighting circuit has been completely inst installed, alled, but before 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 screwed into the sockets of o one ne series, one lamp at a time, starting at 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 the ground is screwed in c. lamp on the high side of the ground ground is screwed in d. last lamp is screwed in
The grounded leg of a lighting circuit circuit is always connected to the shells of the lighting sockets to a. ground the circuit b. reduce the possib ilit y of accidental shock c. simplify the wiring d. avoid burning out lamps
Light fixtures suspended from from chains should be wired so th that at 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
number 8 wire
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 iis s a.c. a.c. or d.c. c. whether a circuit is overloaded d. for grounds on 12 1200-volt 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 ne necessity cessity of providing a special special lighting transformer transformer d. one side of the circuit is grounded
When te testing sting a lighting circuit for grounds, grounds, the the device which would be least useful is a. a lamp bank b. a megger d. a voltmeter c. an ammeter
One advantage of using using series circuits for street lighting is
a. b. c. d. 9.
lower voltage circuit decreased 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 tthe he total illumination supplied by the remaining 4 lamps will be a. b. c. d.
greater for 5the lamps less thanthan for the lamps approximately the same as for the 5 lamps zero because the lamps will burn out almost immediately
10. Your helper suggests that, in order to increase the amount of light on the job you are doing, you should substitute two 100-watt lamps for two of the 36-watt lamps in the lamp bank you are using. If you allow this suggestion the re result sult will be that a. all 5 lamps will burn at normal brightness b. all 5 lamps will be very dim c. the two 10 1000-watt watt lamps lamps will be dim, a and nd the other 3 will be very brig ht d. the two 100-w 100-watt att lamps will will be very bright, and tthe he o other ther 3 will b be e dim 11. Two 120-volt lamps are connected in series across a 120-volt battery which is ungrounded. The common connection of the lamps is grounded. grounded. If the lamp which is connected directly tto o the negative side of the battery should have a broken filament, a ground fault on the negative side of the battery would be indicated by a. both lamps being dark b. the good lamp being lit at full brilliancy c. the good lamp being short-circuited d. the good lamp being lit at approximately half brilliancy 12. A bank of 5 similar 120 volt lamps in series was to be used across a 600 volt line to furnish illumination. When connected across the 600 volt source the first lamp remained dark and the other lamps lit up extra brilliant for a few moments and then went dark. The probable cause of this action was that a. the line voltage was too low to light all lamps b. socket of the first lamp had an open circuit c. all lamps were defective d. socket of the firs t lamp was short ed 13. An electrician, using a standard five-in-series lamp bank containing 130-volt, 36-watt lamps, removes the two of the 36-watt lamps and replaces them with two 30-volt, 1.6-ampere lamps. The most likely immediate result will be that the a. two 30-volt 30-volt lamps will remain dark dark and and the three 130-volt 130-volt la lamps mps will be very bright b. three 130-volt lamps will remain dark and the two 30-volt lamps will be very very bright c. two 30-volt lamps will burn out d. three 130-volt lamps will burn out 14. Of the ten lamps in two adjacent 5-lamp series which are connecte connected d to the same circuit, four of the lamps are uniformly bright and the other six are u uniformly niformly dim. A possible cause of this condition is that a. two sizes of lamp have been used b. one socket in each series is partially short circuited c. there is a cross be between tween the two series d. there is a ground on one of the series
15. In order to use fluorescent lighting in a building which has only a 110 volt DC supply, it is necessary to use a. fluorescent lamps designed for DC b. fluor escent fixtu res with an approved DC auxiliary or induct ance unit and a series resistance of the corr ect value c. fluorescent fixtures ordinarily used on AC d. fluorescent fixtures ordinarily used on AC but equipped with a rectifier 16. An unbalanced load of incandescent lamps is connected on a 3-wire D.C. circuit. circuit. If the neutral wire should become opened at the service a. all the lamps will be extinguished b. nothing will happen and the lamps will continue to burn at the the same brilliancy before the neutral became opened c. the lamps on the less loaded side will burn with greater bril liancy and possib ly burn out d. the lamps o on n the more loaded side will burn with greater brilliancy th than an originally 17. An electric light bulb operated a att more than its rated voltage voltage will result in a a. longer life and dimmer light b. longer life and brighter light c. shorter life and brighter light d. shorter life and dimmer light 18. In a bowling alley, the lighting is satisfactory under normal conditions but when the electric heaters are turned on during cold weather the lights become dimmer and the lighting is insufficient. The factor which probably contributes most to this effect is th the e a. distance from the source of power b. size of the circuit fuses c. current taken by the lamps d. size of the circuit conductor 19. A certain lighting circuit is now wired with No No.. 14 AWG wire. Additional lamps to be added to the circuit will increase the current beyond the capacity of this size wire. The wire of equal length and the same material required to replace the No. 14 wire will have a. greater weight and lower resistance b. less weight and lower resistance c. greater weight and higher resistance d. less weight and higher resistance 20. A certain fiv five-lamp e-lamp series clust cluster er has 36-watt lamps installed. installed. If these lamps lamps are replaced with five 100-watt lamps, the result will be that the a. fuse for the circuit will blow b. lamps will burn out very quickly c. amount of light will be increased d. lamps will be very dim 21. A group of 5 lamps is connected connected in series and each lamp is rated at 130 volts. For full voltage burning of the lamps, the voltage of the supply which feeds these t hese circuits must be a. 650 vol ts b. 260 volts c. 130 volts d. 26 volts 22. 22 lamps a are re all connected in a single ser series ies circuit which is fed at 600 volts. The voltage rating of each individual lamp in the series must be approximately a. 600 volts b. 120 volts c. 30 volt s d. 22 volts 23. The most satisfactory temporary replacement for a 40-watt, 120-volt incandescent lamp, if an identical replacement is not available, is a lamp rated at
a. 100 watts, 240 volts b. 60 watt s, 130 vol ts c. 40 watts, 32 volts d. 15 watts, 120 120 volts 24. If the applied voltage on an inca incandescent ndescent lamp is increased 10%, tthe he lamp will a. have a longer life b. consume less power c. burn more brightly d. fail by insulation breakdown 25. To whet whether her awire 110-volt circuit is alive, a. test touch each in turnlighting to ground b. touch the ends of the wires together c. use a volt meter across the line d. use an ammeter across the line 26. If two identical lamps normally connected in parallel to a 110 volt line are reconnected to be in series across the same line, they will a. give more light b. give less light c. consume more power d. consume consume the the same power power 27. A lamp bank con consists sists of five 100-watt bulbs connected connected to 600 volts. volts. If one of these bulbs is broken and replaced with a 25-watt 120-volt bulb, the a. 25-watt 25-watt bulb will burn out b. 100-watt bulbs will burn out c. 100-watt bulbs will be brighter d. 25-watt bulb will be very dimly lighted
28. The cold resistance of a 120 vol voltt 100 watt Tungsten incandescent lamp iis s a. greater than its hot resistance b. smaller than the hot resistance c. approximately 100 ohms d. equal to the hot resistance 29. If a 110-volt incandescent lamp is burned at 130 volts the result will be a. less than normal light b. short er lamp life c. a blown circuit fuse d. decreased lamp efficiency 30. The resistance of the ttungsten ungsten filament in any incandescent lamp lamp is a. highest when the lamp is off b. highest when the lamp is on c. lowest when the lamp is on d. approximately the same at all times 31. With respect to com common mon electric light bulbs, it is correct to state that the the a. circuit voltage has no effect on the life of the bulb b. filament is made of carbon c. base has a left hand thread d. lower wattage bulb has the higher resistance
32. When an incandescent lamp to be u used sed for general lighting has a mogul base it is a posit positive ive indication that it is rated at over a.
300 watt s
33. The efficiency in lumens per watt of a 10 watt fluorescent lamp a. is less than of a 40 watt incandescent lamp b. is the same as that of a 40 watt incandescent lamp c. is the greater than that of a 40 watt incandescent incandescent lamp d. may be greater or less than that of a 40 watt incandescen incandescentt lamp, depending on the manufacturer 34. The average life of a 100 wat wattt incandescent light bulb is approximately a.
1000 1000 hrs .
35. The filament of a regular incandescent electric lamp is usually made of a. tungsten b. carbon c. nickel
36. With respect to fluo fluorescent rescent lamps it is correct tto o say that a. the filaments seldom burn out b. they are considerably easier to handle than incandescent lamps c. their efficiency is less than the efficiency of incandescent lamps d. the starters and the lamps must be replaced at the same ti time me 37. A method which is sometimes used to increase the useful life of incandescent lamps is to a. burn at less than rated volt age b. burn at more than rated voltage c. turn the lamps off when not needed d. prohibit the use of shades 38. One disadvantage in using fluorescent instead of incandescent lighting is that, compared to incandescent lamps, fluorescent lamps a. are more diff icult to handle b. provide less light for the same power c. give more glare d. have shorter lives 39. Fluorescent lamps compared to incandescent lamps a. emit more lumens per watt b. are more adversely affected by vibratory conditions c. are less critical to voltage dips or variations d. cannot be adapted to D.C. operation 40. The a. b. c. d.
inert gas present in an incandescent lamp is primarily int intended ended to increase the luminous output decrease decrease the filament eva evaporation poration activate the surface of the filament reduce the hazards when the glass is shattered
An interior telephone sy system stem in which each party or station may call any other other statio station n but on which there may be only one conversation without interference is called
a. b. c. d. 2.
selective ringing, selective talking sele selective ctive ringing, common talking code ringing, common talking no name as it does not exist
The following following equipment must be used used on a “2-Line, Return Call” signal system a. 2 bells, 2 metallic lines, 2 ordin ordinary ary push b buttons uttons and 2 set sets s of batteries b. 2 bells, 2 metallic lines, 2 return call push button s a and nd 2 sets of batteries c. d.
2 return turn ry call push buttons and set batteries batteries 2 bells, bells, 2 2 metallic metallic lines, lines, 2 2 re ordina ordinary push b buttons uttons and 11 set ofof batteries
The function of the the “Retard” or Impedance Coil in a Selective Ringing-Common Talking interior telephone system is a. to prevent talking current from passing through the transmitter b. to pre prevent vent the shunting of voice currents through the batte battery ry c. to decrease the distance over which you may speak d. to prevent the ringing current from passing through the receiver
An interior fire-alarm system system best suited to the needs of such buildings buildings as hospitals, public schools, institutions, etc., would be an a. open-circuit, non-code, non-supervised system b. closed-circuit, non-code, supervised system c. closed-circuit, box code, supervised system d. closed-circui t, box code, pre-signal, supervis ed system
Interior Fire Alarm Systems may be divided into a. two basic groups – Pre-signal and Dual b. 1 group only – open circuit c. 1 group only – closed circuit d. two ba basic sic groups – open circuit and and closed circuit
An open circuit type of Interior Fire Alarm Systems consists of a. vibr ating gongs and break glass stations b. single stroke gongs and break glass stations c. vibrating gongs and coded stations d. electrically supervised gongs and boxes
Modern approved Closed Circuit Fire Alarm Sy Systems stems should should h have ave the the following trouble indicators a. trouble light only b. milli-ammeter only c. trouble bell only d. mill i-ammeter, i-ammeter, time limi t device and troub le bell and light
An approved Closed Circuit Type of Interior Fire Alarm should consist of a. mechanical gongs and coded stations b. vibrating gongs and coded stations c. electrically supervised gongs and and stations a and nd may be coded or not d. single stroke gongs and strap key
The electric energy required to raise the temperature temperature of the water in a pool is 1000 kwh. The heat losses are 25 percent. percent. The total heating energy required is a. 1000 kwh b. 1250 kwh d. 1500 kwh c. 1333 1333 kwh
10. A 6000 watt 3-phase heater composed of three resist resistance ance units in delta is connected to a 3phase 208 volt supply. The resistance, in ohms, of ea each ch resistance unit is most nea nearly rly b. 41.6 c. 83.2 d. 208 a. 20.8 11. Based upon the data given in question 10, if the the 3 heater resistance units are now connected in star (or wye) to a 3-phase 208 volt supply, the power in watts consumed by this heater is most nearly a. 10,400 b. 6,000 c. 3,500 d. 2,000 12. A resistor is connected across a supply of E volts. The heat produced in this resistor is 2 proportional to I R. If R is reduced in value, the heat produced in this resistor is now a. increases b. decreases c. remains the same d. is indeterminate 13. An A.C. current of one ampere R.M R.M.S. .S. flowing through a resistance of 10 ohms has the same heating value as a D.C. current of a. one ampere flow ing throu gh a 10 ohm resistance b. one ampere flowing through a 5 ohm resistance c. two amperes flowing through a 10 ohm resistance d. five amperes flowing through a 1 ohm resistance
The a. b. c. d.
One type type of electric motor te tends nds to “run away away “ if it is not always conne connected cted to its load. This motor is the a. d.c. seri es b. d.c. shunt c. a.c. induction d. a.c. synchronous
A motor which will not operate on d.c. is the a. series motor b. shunt motor c. induction motor
most common type of motor that can be used with both A-C A-C and D-C sou sources rces is the repulsion motor the series motor the rotary converter the shunt motor
d. synchronous motor
The type of motor that does not have a commutator is the a. synchronous b. shunt c. squirr el cage
The torque of a shunt motor varies as a. the armature current b. the square of the armature current c. the cube of the armature current d. the cube of the field current
If tthe he field of a shunt motor while running under no lead opens, the motor will a. stop running immediately b. continue to run at a very slow speed c. run away d. gradually slow down until it stops
In a 5 H.P., 220-volt shunt motor rated rated at 19.2 amperes and 1500 r.p.m., the armatur armature e resistance is a. smaller than that of the shunt field b. larger than that of the shunt field c. the same as that of the shunt field d.
always ½ as large as that of the shunt field
Comparing the the shunt field winding with the the series field winding of a compound d.c. motor, motor, it would be correct to say that the shunt field winding has a. more turns but the lower resistance b. more turns but the higher resistance c. fewer turns and the lower resistance d. fewer turns but the higher resistance
In selecting a starting box for a d.c. shunt motor it would be necessary to know the motor a. b. c. d.
shunt fieldresistance resistance and current armature and field full load curr ent full load current and speed field current, full load current and speed
10. It is desired to run a d.c. shunt motor at a speed lower than its rated speed. The most practical way to accomplish this would be to connect suitable resistance in a. series with the field b. series wit h the armature c. parallel with the field d. parallel with the armature 11. If the two line leads of a D.C. series motor are reversed the motor will a. not run b. run backwards c. run the same same as as before d. become a generator 12. In the the selection of a direct curren currentt motor motor a. a seri series es motor should be chosen wh where ere the motor is operat operated ed at very light loads b. a series motor should be used w where here the required starting torque is low c. a series moto r should be used where the required starting torque is high d. a shu shunt nt motor should be used where the st starting arting tor torque que required is high and it starts under loaded conditions 13. In the case of a compound wound D.C. motor operating at constant voltage, with a very light load, increasing the resistance which is in series with the shunt field will a. have no effect on the motor speed b. cause the motor to slow down c. cause the motor to either speed up or slow down down depending on the the type of load load d. cause the motor to speed up 14. To change the direction o off rotation of a cumulative wound D.C. motor you you must a. reverse the connectio ns to the armature b. reverse the connections to the shunt field c. reverse the connections to the series field d. do nothing as it cannot be done 15. Series type motors motors for electrically driven driven rheostats or governors have a split series field a. for better speed control b. to change the direction of rotation c. to produce a greater starting torque d. for more accurate voltage regulation 16. To a. b. c. d.
start a 7 ½ H.P., 220-volt, D.C. motor you should use a compensator an across the line starter a suitable startin g box a “Start-Run” switch
17. In the D.C. series motor when the load torque is decreased, th the e
a. b. c. d.
armature rotates at a lower speed armature rotates at a higher speed current through the field is increased current through the armature is increased
18. Series type motors for electrically driven rheostats or governors have a split series series field to a. b. c. d.
obtain lowthe motor speed decrease current consumption change the directio n of rotatio n produce greater starting torque
19. In the D.C. series motor, the field a. has comparatively few turns of wire b. has comparatively many turns of wire c. is connected across the armature d. current is less than the line current 20. To properly start a 15 hp. D.C. compound motor, you should use a a. transformer b. 44-point point starting rheostat c. compensator
21. The ordinary direct current series motor does not operate satisfactorily with alternating current. One of the main reasons for this is a. excessive heating due to eddy eddy currents in the solid parts of the field structure b. that the a armature rmature current and field current are out of phase with with each each other c. that the field flux lags 120° in time phase with respect to the line voltage d. excessive heating due to the low voltage drop in the series field 22. A d.c. elevator motor, on a gearless traction machine, has a series field for compounding during the acceleration period. This field is cut out when the motor has reached full speed, speed, for the purpose of a. preventing excessive heat b. reducing the line current c. provi ding constant speed over a wide range of load condit ions d. saving the cost of losses in the series field e. providing the same speed in the up and down directions 23. The temperature of the shunt shunt field of a d.c. motor motor increases fro from m 20°C to 60°C after 3 hours operation. This increase in temperat temperature ure of the field coils a. will have no effect on the operation of the motor b. will tend to slow down the motor due due to an increase in the resistance of the the field coils c. will tend to speed speed up the motor due to a an n incr ease ease in re resistance sistance of the field coils d. will tend to slow down the motor due due to a decre decrease ase in resistance of the the field coils 24. A d.c. series motor a. cannot be used for driving loads that require high starting torque b. is a constant speed motor c. should be directly connecte connected d to its loa load d d. may run away if iits ts field becomes opened 25. The a. b. c. d.
total developed torque of a d.c. motor is dependent upon the armature curr ent and the flux per pole the speed of the motor the type of armature winding none of the above
26. Of the following statements, the one which is most accu accurate rate concerning D.C. motors is a. a lap-wound motor has two brushes regardless of the number of poles b. a series-wound motor has as many brushes as there are poles c. a lap-wound motor has has as many brush es as there are poles d. regardless of the type of armature winding the number of parallel paths is always two 27. Interpole windings in direct curr current ent motors ar are e used primarily a. b. c. d.
as a means for varying the speed of the motor to reduce armature reaction increase the efficiency of the motor to compensate for field leakage
28. The best best way way to start a la large rge shunt shunt motor is with with a. a weak field b. full voltage in the armature
c. a compensator
d. a stron g field
29. If two of the three line leads to a three-phase squirrel-cage induction motor are interchanged the motor will a. reverse its directio n of rotatio n b. be shorted c. not run d. run above synchronous speed 30. One a. b. c. d.
identifying feature of a squirrel-cage induction motor is that it has no windings on the stationary part commutator or slip rings air gap iron core in the rotating part
31. Large squirrel cage induction motor motors s are usually started at a volt voltage age considerably lower than line voltage to a. avoid excessive startin g current b. obtain a low starting speed c. permit starting under full load d. allow the rotor current to build up gradually 32. To reverse the direction of rotation of a 3-phase motor, it is ne necessary cessary to a. increase the resistance of the rotor circuit b. interchange all three line connections c. interchange any two of the three line connectio ns d. reverse the polarity of the rotor circuit 33. To reverse the direction of rotation rotation of a Split-Phase motor y you ou would a. do nothing as it cannot be done b. reverse the main lines c. reverse the polarity of all windings d. reverse the polarit y of the starting or auxiliary wind ing 34. Speed control by a method that requires two wound rotor induction motors with their rotors rigidly connected together is called speed control by a. change of poles b. field control c. concatenation d. voltage control 35. To properly start a 15 hp. 3-phase induction mot motor, or, you should use a a. shunt
b. 4-point starting rheostat
36. To reverse the direction of rotation of a rrepulsion-induction epulsion-induction motor y you ou should a. loosen the set screw and move rocker arm to proper place b. interchange the terminal connections c. increase the line voltage d. do nothing as it cannot be done 37. A certain machine machine is driven by a 1750 rr.p.m, .p.m, d.c., shunt motor. If the power supply is to be changed to three-phase, 60 cycles, a.c., the most suitable replacement motor m otor would be a a. series motor b. repulsion motor c. squirrel-cage squirrel-cage induction motor d. capacitor motor 38. The correct method method of measuring the power taken by an a.c. electric electric motor is to use a a. wattmeter b. voltmeter and an ammeter c. power factor meter d. tachometer 39. To a. b. c.
start a 7 ½ H.P., 3-Phase, 208 –volt A.C. motor you should use a “4 point” starting box a “ 3 point” sta starting rting box a M-G set
d. an across-the-line starter 40. A repulsion motor is equipped with a. slip rings b. a commu tator c. neither a commutator nor slip rings d. both a commutator and slip rings 41. The synchronous speed of a 25 cycle 10 pole motor is a. 250 R.P.M. b. 600 R.P.M. c.
42. Increasing the field excitation of a synchronous motor above its normal v value alue when the load remains constant will a. result in a leading power factor b. result in a lagging power factor c. result in either a leading o orr lagging power factor depending on the kind o off load d. have no effect on the power factor 43. An advantage advantage of a sy synchronous nchronous motor over a wound-rotor wound-rotor inductio motor is that a. its speed may be more readily controlled b. its speed does not depend on the frequency c. it has no brushes to contend with d. the power factor of the mot or may be varied 44. In a compound motor, the series field as compared compared with th the e shunt field a. carries more curr ent b. has higher resistance c. has finer wire d. has more turns of wire
45. It would b be e accurate accurate to state state that a. opening the series field of a compound motor accelerates the motor
b. c. d.
increasing the field excitation of a synchronous synchronous generator generator causes causes the the power factor to become less lagging opening the shunt field of a shunt motor accelerates accelerates the motor decreasing the field excitation of a syn synchronous chronous motor causes the power factor factor tto o become less lagging
46. If you tried tried to start a compound motor in which the series field was open circuited, the motor a. woul d not sta start rt b. would blow the fuse c. would “Run Away” d. would reverse 47. The a. b. c. d.
proper way to reverse the direction of rotation of a compound motor is to interchange the line leads interchange the armature connectio ns interchange the shunt field connections interchange the series field connections
The gears gears most commonly used to connect two shafts which intersect are u usually sually a form of of a. Spur gears b. Bevel gears c. Spiral gears d. Herring bone gears
Assume that the field leads of a large, completely completely disconnected d.c. motor are not tagged tagged or otherwise marked. You could readily tell the shunt field leads fro from m the series field leads by the a. length of the leads b. c. d.
size of wire thickness of insulation type of insulation
On motors with brakes, the brake magnet coil is a. de-energized when current is fed to motor b. energized energized when current is fed to motor c. energized after motor reaches normal speed d. de-energized after motor reaches low speed
The commutator bars of a motor are made of a. mica b. carbon c.
Simplex lap windings have as many armature circuits as there are a. commutator bars b. number of coils c. number of active conductors
Pigtails are used on carbon brushes to a. hold the brush in the holder b. supply the proper pressure c. make a good electrical connecti on d. compensate for wear
When thermal thermal overload overload relays are used for the p protection rotection of polyphase polyphase induction motors their primary purpose is to protect the motors in case of a. reversal of phases in the supply b. low line voltage c. short circuit between phases d. sustained overload
The one of the following devices which is commonly used used to prevent damage in case of reversal of leads in reconnecting the wiring of three phase motor is a a. b.
reverse current relay reverse power relay
reverse phase relay reverse power factor relay
Motor frames are are usually positively gro grounded unded by a sp special ecial connection in order to a. remove static b. protect against lightning c. provide a neutral d. protect against shock
10. The a. b. c. d.
protective protective device for a motor branch circuit should h have ave a rating equal to or greater greater than the starting current of the motor should have a rating equal to the full load current of the motor should not be of the instant ane aneous ous type should have a rating equal to the current capacity of the circuit conductors
11. When both fuses and thermal cutouts are used in a motor circuit, the a. ratings of the fuses should be the same as tthose hose of the the thermal cuts b. fuses are used to protect against continuous, but not large overloads c. thermal cutou ts are used to protect aga against inst conti nuous overloading d. thermal cu cutouts touts are used to protect protect against short-circui short-circuits ts in the motor and branch circuit 12. An induction motor circuit would never be protected by a. fuse b. a thermal cut-out c. an overload relay d. a reverse reverse power re relay lay 13. Most motor starters are are provided with either an undervoltage protective device or a an n undervoltage release device. A starter with an a. undervolt age protectiv e device woul d be used to open a suppl y circu it upon failure or reductio n of volt age and keep keep it open until m anually closed b. undervoltage protective device would be used to open a supply circuit upon failure or reduction of voltage and automatically re-close it upon return of normal voltage c. undervoltage protective device controls the motor voltage and keeps it at a safe value d. undervoltage release device would be used to prevent opening a supply circuit when voltage fluctuations occur in the power system s ystem 14. A polyphase motor may be protected against reversal of rotation by using a a. reverse speed relay b. reverse power relay c. reverse phase relay d. reverse current relay
15. A newly installed three phase induction motor which is to drive a pump is fou found nd to be rotating in the wrong direction. This can be correct corrected ed by a. connecting the motor to the other end of the pump b. interchanging all three leads c. interchanging any two motor leads d. a quick opening and re-closing of the main line switch 16. To change the direction of rotation of a cumulative cumulative compound-wound, d.c. moto motorr and maintain its characteristics you must a. reverse the connecti ons to the armature b. reverse the connections to the shunt field c. reverse the connections to the series field d.
reverse the connections to the armature and the series field
17. In normal operation, operation, one type o off fault that is not likely to develop in the armature of motors and generators is a. short circuit b. open circuit c. ground d. reversed coils 18. If you attempted attempted to start a d.c. compound motor in which the series field was o open-circuited, pen-circuited, the motor a. woul d not start b. would blow the fuse c. d.
would run away would start in the reverse direction
19. To temporarily change the direction of rotation rotation of a single-phase, shaded-pole, induction motor you would a. do nothi ng since it cannot be done b. reverse the connections to the starting winding c. shift the brushes to the opposite neutral d. reverse the line leads 20. For maximum safety the magnetic cont contactors actors used for rreversing eversing the direction of rotation of a motor should be a. electrically interlocked b. electri electri cally and mechanically interloc ked c. mechanically interlocked d. operated from independent sources 21. Silver electrical contactors are tarnished most read readily ily by a. oxygen b. hydrogen c. nitrogen
22. The lubricant used for sleeve bearings on motors is usually a. vaseline b. oil c. graphite
23. The correct method method of measuring the power taken by an a.c. electric motor is to use a a. wattmeter b. voltmeter and an ammeter c. power factor meter d. tachometer 24. To measure the power taken by a d.c. electric motor with only a single instrument you should use a. voltmeter b. an ammet d. a power factor meter c. a watt meter
25. The a. b. c. d.
speed of a d.c. shunt motor is generally regulated by means o off a switch for reversal of the armature supply source of variable supply voltage variable resistance in the armature circuit rheostat in the field circu it
26. A carbon brush in a d.c. motor should exert exert a pressure of about 1 ½ lbs. per square inch on the commutator. A much lighter pressure would be most likely to result in a. sparking at the commu tator b. vibration of the armature c. the brush getting out of line d. excessive wear of the brush holder 27. New brushes for a motor should be fitted to the commutator by using a a. round file b. half-round file c. stri p of sandpaper d. strip of emery cloth 28. One sure sign that there has been sparking at the brushes of a stopped d.c.motor d.c.motor would be
a. b. c. d.
the odor of hot rubber insulation hot bearings grooves worn around the commutator pits on the commutator surface
29. A common way of reducing the chances of u uneven neven commutator wear is to a. use brushes of different hardness b. allow some end play in the motor be bearings arings c. d.
anneal the commutator after assembly turn the commutator down frequently
30. If an unusual amount amount of dust is found found around the base of a motor wh which ich is being inspected, the proper procedure to follow is to a. take no action but report the motor for further inspection b. remove the dust c. inspect the bearings for signs of excessive wear d. lubricate the motor 31. If one bearing housing housing of a running motor feels exceptionally hot but there is no unusual vibration, the most logical conclusion is that the a. the motor is being overloaded b. bearing bearing needs lubr ication c. shaft has become worn d.
motor has been running a long time
32. While a certain d.c. shunt motor is driving a light load, part of tthe he field winding becomes short circuited. The motor will most likely a. increase its speed b. decrease its speed c. remain at the same speed d. come to a stop 33. To measure the voltage and current supplied to a D.C. motor, connect th the e a. voltm eter across the line and ammeter in series wit h the motor b. ammeter across the line and voltmeter in series with the motor c. voltmeter and ammeter in series with the motor d. voltmeter and ammeter across the line
34. A practical method of of checking the magnetic p polarity olarity of the field poles of a direct current current motor is by the use of a. an iron or steel tool b. iron fillings c. a magnetic compass d. a megger 35. The a. b. c. d.
reason for using using oil rings in bearings is to increase the bearing surface maintain proper oil level prevent oil leaks lubri cate the bearing
36. A condition which will not cause a brush on tthe he collector ring to carry less than its share of the current is a. low brush pressure b. low resistance of the brush c. an insulating glaze on the brush face d.
a loose shunt or pigtail
37. A good practical test to determine whether a wet wetted ted down motor has been sufficiently dried out is a. an insulatio n test b. an armature resistance test c. a high-voltage break down test d. a flash over test 38. You are running a D.C. motor the armatu armature re of which has an open coil. You could identify this condition by a. increase in motor speed b. decrease in motor speed c. the coil getting excessively hot d. seeing seeing a and nd hearing hearing a prono unced electric arc arc under the brushes a as s the defective coil passed 39. If, in tracing tracing through an armature winding, all of the conductors are encountered encountered before coming back to the starting point, there is but one closure and the winding is a. doubly reentrant b. singl y reentrant c. triply reentrant d. quintuply reentrant 40. If a main unit unit is operating at full load with a leading power factor for several hours, the part you would expect to become overheated would be the a. brushes and rings b. field rheostat c. armature winding d. field winding
41. A certain wound rotor induction motor is eq equipped uipped with a variable resistor in the rotor circuit for starting purposes purposes only. It is desired to replace this resistor w with ith one that can be used also for motor speed control. Compared with the original resistor, tthe he new resistor should should have a. higher total resistance b. lower total resistance c. higher curr ent carryin g capacity d. lower current carrying capacity 42. If the no-load speed of a squirrel cage type induction motor connected to a three phase phase 25 cycle line is 373 rpm, the motor has a. 2 poles b. 4 poles c. 6 poles d. 8 poles 43. The power drawn by a three-phase induction motor which draws 15 amperes at 2200 volts and power factor of 80% is given, in watts, by the product of a. 15 x 2200 x 0.80 b. 15 x 2200 x 1.41 x 0.80 c. 12 x 2200 x 1.73 x 0.80 d. 12 x 2200 x 3.00 x 0.80 44. It is desired to limit the starting current to the armature of a D.C. motor taking taking current from a 120 volt source to 10 amperes. If the armature resistance is 0.2 ohms, the resistance in the armature circuit should be a. 118 ohms b. 11. 11.8 8 ohm s c. 120 ohms d. 20 ohms 45. When measuring the speed of a d. d.c. c. motor by means of a stop-watch and a revolution counter, the stop stop watch as started when the revolution counter read 50. At the end of 80 80 seconds the counter read 1,650. The average RPM of the moto motorr during this period was a. 200 b. 1,200 c. 1,600 d. 1,700 46. The input to a motor is 16,000 watts and the motor losses total 3,000 watts. The efficiency of the motor is most nearly
47. While a certain d.c. shunt motor is driving a light load, part of tthe he field winding becomes short circuited. The motor will most likely a. increase its speed b. decrease its speed c. remain at the same speed d. come to a stop 48. When a certain motor is started up, the incandescent lights fed from from the same circuit dim sown somewhat and then return to approximately normal brightness as the motor comes up to speed. This definitely shows that the a. starting current of the motor is large largerr than than the running current current b. insulation of the circuit wiring is worn c. circuit fuse is not making good contact d. incandescent lamps are too large for the circuit 49. If a single-phase induction motor draws 10 amperes at 240 volts, the p power ower taken by the motor a. will be 2400 watts b. will be more than 2400 watts c. will be less than 24 2400 00 watts d. may be more o orr less than than 2400 watts depending on the power factor 50. A coil of wire wire wound on an iron core draw draws s exactly 5 amperes amperes when connected connected across the terminals of a ten-volt storage batt battery. ery. If this coil is now now connected across the the ten-volt secondary terminals of an ordinary power transformer, the current drawn will be be a. less than 5 amperes b. more than 5 amperes c. exactly 5 amperes d. more or less than 5 amperes depending on the frequency 51. If the speed of a synchronous motor connected to a 60-cycle power line is 1 1200 200 rpm, the number of poles it must have is a. 2 b. 4 c. 6 d. 8 52. Under load, the current in the armature conduct conductors ors of a DC dynamo give rise to to an independent excitation which alters both the magnitude and distribution of the flux produced by the field alone. This magnetizing action of the armature armature is called a. armature reaction b. dynamic breaking c. field reaction d. radial excitation
The part of a circuit w which hich melts when tthe he current abnormally exceeds exceeds the allowable carrying of the conductor is called a. circuit breaker b. thermo cutout c. overload trip d. fuse
If a fuse becomes hot under normal load, a probable cause is a. rating of the fuse is too high b. rating of the fuse is too low c. insuf ficient pressure at the fuse clip s d. excessive tension in the fuse clips
If it were necessary necessary to replace a 50-ampere cartridge fuse with a 65-ampere car cartridge tridge fuse of the same voltage rating, it would always be necessary to replace a. b.
all wiring in the protected circuit the renewable link in the fuse
c. d. 4.
the fuse only the cut-out and the fuse
Good practice practice requires that cartridge cartridge fuses be removed removed from their clip clips s by using a fuse puller rather than by using the bare hand. The reason for using the fuse puller is that the a. fuse clips may be damaged by pulling at the wrong angle b. fuse is less likely to break c. bare hand may be burned or otherwi se injur ed d.
use of the bare hand slows d down own removal of fuse and causes arcing
The a. b. c. d.
one of th the e following statements about a plug fuse tthat hat is most valid valid is that it should always be screwed in lightly to assure easy removal never be used to hold a coin in the fuse socket never be replaced by someone unfamiliar with the circuit always be replaced by a larger size if it burns out frequently
A fuse puller is used in replacing a. plug fuses b. link fuses
c. ribbon fuses
d. cartridg e fuses
The most important reason for using a fuse-puller when removing a cartridge fuse from the fuse clips is to a. prevent blowing of the fuse b. prevent injury to the fuse element c. d.
reduce arcing the chances of personal injur y reduce at the fuse clips
If a fuse clip becomes hot under normal circuit load, the most pro probable bable cause is that that the a. clip makes poor contact with the fuse ferrule b. circuit wires are too small c. current rating of the fuse is too high d. voltage rating of the fuse is too low
Before pulling or inserting fuses, it is good practice where possible to a. always make sure that the fuses are blown b. jumper the supply leads c. remove the power from the circuit by opening the switch d. ground all leads on both sides of the fuses
10. The main reason why a blown fuse should nit be bridged temporarily by a copper wire is because a. the wire may disrupt violently when a short circuit occurs b. the circu it may not be prot ected adequa adequately tely against overload c. the wire will maintain an arc when it blows d. there is d danger anger of electric shock by coming in contact with the wire 11. The a. b. c. d.
action of a common plug fuse depends on the principle that the current develops heat heat voltage breaks down a thin mica disk current expands and bends a link voltage develops heat
12. Consumers are are w warned arned never to use a coin instead of a spare spare fuse. The reason for this this warning is that a. the protecti on of the fuse will be lost b. additional resistance will be placed in the circuit c. mutilating coins is illegal
shock hazards is increased
13. Fuse failure because of poor clip contact or loose connections is due to the resulting resulting a. excessive voltage b. increased current c. lowered resistance d. heating effect 14. Oxides should should be removed fro from m fuse contacts by using a. a dull life b. emery cloth c. fine sandpaper
d. a sharp file
15. One result of loose wire connections at the terminal of a fuse clip is stated in the above paragraph to be a. loss of tension in the wire b. welding of the fuse to the clip c. distortion of the clip d. loss of tension of the clip 16. Simple reasoning will show that the oxide film referred to to is undesirable undesirable chiefly because it a. looks dull b. makes removal of the fuse difficult c. weakens the clips d. intro duces undesirable resistance 17. Fuse clips that are bent very slightly a. should be replaced with new clips b. should be carefully filed c. may result in blowing of the fuse d. may prevent the fuse from blowing 18. From the fuse information paragraph it would be reasonable to co conclude nclude that fuse clips a. are difficult to maintain b. must be given proper maintenance c. require more attention than other electrical equipment d. are unreliable 19. A safe practical practical way of checking the tightness of the wire connection to the fuse clip of a live 120-volt lighting circuit is to a. feel the connection with your hand to see if it is wa warm rm b. try tightening tightening with an insulated insulated screw-driver screw-driver or socket socket wre wrench nch c. see if the circuit works d. measure the resistance with an ohmmeter 20. If a cartridge cartridge fuse is hot to the touch when you remove it to do some maintenance on the circuit, this most probably indicated that the a. voltage of the circuit is too high b. fuse clips do not make good contact c. equipment on the circuit starts and stops frequently d. fuse is oversized for the circuit 21. If one end of a cartridge fuse becomes becomes unusually warm, the first action on tthe he part of the electrician should be to a. tight en the fuse clips b. replace the fuse with a larger one c. transfer some load to another circuit d. notify his foreman
22. The length of a stranded cartridge fuse depends on the circuit a. power b. amperage d. type of current (a.c. or d.c.) c. voltage 23. If a fuse of higher than the required current rating is used in an electrical circuit circuit a. better protection will be afforded b. the fuse will blow more often since it carries more current c. serious damage may result to the circui t from overload d.
maintenance of the large fuse will be higher
24. When fuses and thermal cutouts are both used in a motor motor circuit a. the fuses protect the motor against light overloads b. the fuses protect the motor a and nd circuit a against gainst shorts c. the thermal cut-outs protect the motor and circuit against shorts d. the thermal cut-outs protect the motor against overheating 1.
In ordering standard cartridge fuses it is necessary to specify only a. the current capacity b. the voltage of the circuit c. the current capacity and the volt age of the circu it d. the power to be dissipated
The largest size regular plug is rated at a. 15 amperes b.fuse 20used amperes
The range of sizes of cartridge fuses with ferrule ends is from a. 0 to 60 amperes b. 0 to 30 amperes c. 31 to 50 amperes
d. 61 to 100 amperes
A 600-volt cartridge fuse is most readily distinguished from a 250-volt cartridge fuse of the same ampere rating by comparing the a. insulating materials used b. shape of the ends c. diameters d. lengths
Renewable fuses differ from ordinary fuses in that a. burned out fuse elements elements can be replaced readily b. they can carry higher overloads c. burned out fuses can be located more easily d. they can be use on higher voltages
A 10 ampere cartridge fuse provided with a navy blue label has a voltage rating, in volts of a. 220 c. 550 d. 600 b. 250
Knife blade ends on a cartridge fuse are a positive indication that the fuse is rated rated at over a. 600 volts b. 250 volts c. 100 amperes d. 60 amperes
In general, general, the principal factor that determines determines the current rrating ating of the fuse that should be installed in a lighting circuit is the a. wattage of the individual lamps b. capacity of the smallest wire in the circu it c. voltage of the circuit d. capacity of the largest wire in the circuit
Testing for a blown cartridge fuse by connecting a lamp from one clip to the other of the suspected fuse will in all cases indicate a a. blown fuse if the lamp remains dark b. good fuse if the lamp lights up
blown fuse if the lamp lights up good fuse if the lamp remains dark
A blown “one time” fuse is replaced with a good fuse of the same rat rating. ing. When the switch is closed the new fuse also blows. In this case a. a fuse of higher current rating should be used b. a fuse having a greater time lag should be tried c. some of the load should be transferred to another circuit d.
the circu it should be checked before tryi ng another fuse
One of the the two plug-fuses plug-fuses in a 120-volt circuit blows because of a short circuit. If a 120-volt lamp is screwed into the fuse socket while the circuit is still shorted, the lamp will a. burn dimly b. remain dark c. burn out d. burn normally
Before removing a “blown” 600 volt fuse it is always desirable to a. open the circu it at another point on the line side b. shut down the station c. jumper the fuse d. ground the circuit
If the 30 a ampere mpere fuse is blown fre frequently quently on a house lighting circuit a. check the load and condit ion of equipment b. insert a fuse of higher current rating c. d.
insert fuse higher voltage rating check athe lineofvoltage
A 120-volt lighting circuit circuit feeding 10 single-lamp 120-volt fixtures is protected protected by a 15 15-ampere fuse. If the same size lamp is used used in all 10 fixtures the largest largest lamp that can be used without blowing the fuse is a. 100 watts b. 150 watt s c. 200 watts d. 250 watts
The maxi maximum mum siz size e of fuse fo forr prot protecting ecting a 10 HP, 3-phase, 220 volt motor should be a. 20 amperes b. 35 amperes c. 60 amperes d. 75 amperes e. 90 amperes
A 115/230 volt three wire lighting circuit sub-main, supplies fused branch circuits. It has a grounded neutral and consists of 3 no. 8 rubber covered wire wires. s. It should be protected at the distribution panel by a. fuses of not over 35 amperes in all three lines b. fuses of not over 15 amperes in all three lines c. fuses of not over 35 amperes in the ungro unded lin es, with the neutral unfus ed d. fuses o off n not ot over 15 amperes in the ungrounded lines, wit with h the the neutral neutral unfused e. three single pole 35 ampere switches
A piece of electrical equipment that serves tthe he same purpose as a fuse is a a. transformer b. generator c. switch d. circu it breaker
A d.c. panel type circuit breaker is adjusted so that the a. arcing tip will open before the main contact b. main contact will close before the arcing tip c. main contact will open before the arcing tip d. arcing tip and main contact will open at the same time
Arcing tips are used on air circuit breakers to a. increase the contact b. prot ect the main contacts
decrease the arcing time limit the short circuit current
The a. b. c. d.
reason modern circuit bre breakers akers are constructed to be “trip free” is that such breakers cannot be held closed when there is an overload can be closed with less effort cannot be opened accidentally can be opened with less arcing
The push push buttons used in the control circuits of of some remote-controlled lighting switches are required only to make, not break, break, the control circuit. In such cases, the breaking of the the control circuit is generally accomplished by a. a relay on the control panel b. an auxiliary auxiliary contact on the lighting switch c. a blow-out coil on the main contacts of the lighting switch d. an auxiliary toggle switch on the control panel
A breaker is said to be trip free if a. the closin g and trip ping operations are independent b. it will trip on any value of reverse current c. the tripping devices operate easily d. it is not latched in position when closed
A Trip T rip Free Circuitonly Breaker is one a. that is found in large generating stations b. that cannot be re-closed once it opens c. that rings an alarm when it opens d. that cannot be closed by hand hand whil e the abnormal condit ion which ca caused used it to open exists
The trip-coil trip-coil of a circuit breaker is connected into a line thro through ugh a current transformer rated at 200:5 amperes. If normal line curren currentt is 120 amperes and the circuit breaker should open at 125% normal line current, the trip mechanism should be set to operate when the trip-coil current is a. 6.25 amperes b. 3.75 3.75 amperes c. 1.94 amperes d. 14.1 amperes
To wor work k on a high voltage bus with rremote emote con controlled trolled switches, after isolating the bus, the safest procedure before working on the bus is a. short circuit and ground the bus b. tag the control switches on the control board c. notify the shift operator on the control board d. use rubber gloves and mats e. notify the power company supplying the power
10. A copper bus bar an inch in diameter has a cross sectional sectional area of a. 3,141,600 C.M. b. 1,000,000 C.M. c. 785,400 C.M.
d. 100,000 C.M.
11. In order that that a circuit breaker may be remotely opened it must be equipped with which one of the following tripping devices? a. shunt trip b. time-delay trip c. trip-free mechanism d. inverse-time trip 12. The reason modern circuit breakers are constructed to be “quick breaking” is that such breakers a. can be operated at more than 100% rating b. cannot be held closed when there is an overload c. can be opened with less arcing
cannot be closed accidentally
13. The “Normal Current Density” of copper bus is 100 amperes per per square inch. The number of amperes which a 2 ½ x ¼ inch copper bus may carry under these conditions is b. 1000 amperes c. 1250 amperes d. 500 amperes a. 625 amp eres 14. The weight of a 10 foot section of a 2” x 1/8” copper bus bar, which is made of copper having a density of 0.32 lbs. per cu. in., is most nearly a.
9.6 lbs .
A bake-out is generally considered necessary for a rectifier if a. it has been subjected to a heavy overload b. it has been operating at light load for a long period c. more than three months have elapsed since previous bake-out d. it has been been open to atmosphere for a long period period
The possibility of an arc back in a rectifier is increased by a. operating the rectifier at less than rated capacity b. the presence of mercury vapor in the rectifier tank c. the absence of non-condensible gases in the rectifier tank d. operating the rectifi er at more than rated capacity
The material that is least suitable for rectifier vacuum seals is a.
A commonly used method of controlling the d.c. voltage of of a rectifier is by a. inserting a rheostat in the main positive lead b. varying the tank pressure c. controlling the potentia potentiall of the anode grids d. increasing or decreasing the interphase transformer ratio
A co copper pper oxide rectifier consisting of four units arranged in a full-wave bridge circuit is to be used to charge a 6-volt storage storage battery. The rectifier may be considered as having a linear volt-ampere characteristic yielding 6 amperes when the voltage drop across each unit is 3volts. The average charging current whe when n the peak value of the applied alternating alternating voltage is 20 is approximately b. 14 c. 8.1 d. 10 a. 6.7
In a multi-anode rectifier, anode grids are provided to a. give mechanical support to the anode tips b. permit convenient access to the anodes c. increase the heat radiating surface of the anodes d. control the rectifie rectifierr arc
The surge eliminator for a rectifier is connected a. across a secondary wind ing of the power transfor mer b. across a primary winding of the power transformer c. from the tank to the cathode d. from the cathode to the negative bus
One important function of the anode screens in multi-anode rectifiers is to a. reduce the frequency of arc backs b. prevent particles of graphite from dropping into cathode pool c. protect the anodes from the heat of the arc d. control the temperature of the anodes
Most of the large mercury arc rectifiers in com-single-phase or 3-phase rectifiers. One of the principal reasons for this is that a. a smoot her, more even d.c. volt age is obtained b. the cathode is required to carry a smaller current c. less routine maintenance work is required d. an even number of phases is essential for good operation
Burnt or pitted contact studs on a synchronous generator field rheostat should be a. dressed with a file b. smoothed with emery cloth c. restored with a burnishing tool d. resurfaced by brazing
If a an n open circuit is discovered in an exciter exciter shunt field rheostat between two two contact points, the exciter a. must be left out of service until the open coil or grid is replaced b. can be operated if the open coil or grid is short -circu ited c. must be operated at low loads with reduced field d. can be operated without without tthe he field rheostat by exciting exciting the field from the exciter bus
Series ty type pe motors for electrically electrically driven rheostats rheostats or governors have a split series field to a. obtain low motor speed b. c. d.
decreasethe thedirectio currentnconsumption change of rotatio n produce greater starting torque
A rrelay elay coil with a resistance resistance in series is connected in parallel with a contactor contactor coil to a battery. If the current is 5 amperes in the relay coil, 5 amperes in the resistor and 3 amperes in the contactor coil, the battery current is a. 13 amperes b. 2 amperes c. 5 amperes d. 8 amperes
The electrical device occasionally connected across contacts to minimize arcing when the contacts open is a. a condenser b. a resistor c. an inductance coil d. a carbon tip
An induction type over-current relay usually a. operates instantaneously b. has a constant time delay for all settings c. has increased time delay with an increase in current d. has decreased decreased tim e delay with a an n increase in current
An electr electrical ical helper notices th that at a certain relay does not pick up promptly when its control circuit is closed. Of the following faults, the only one one that could be the cause of this delayed operation is a a. control wire broken off one of the relay terminals b. burned out fuse c. burned out relay coil d. fuse making poor contact
Differential relays are installed to protect against a. overcurrents overcurrents b. reverse currents c. internal faults
d. no voltage e. reverse power
A hesitating relay is a. to allow for momentary momentary impulse type closing control b. to provide a definite time for tripping as overload
c. d. e.
one that stops half way unless interlock circuits are clear an a.c. relay with insufficient shading used for remote control of field rheostat motors
10. An induction type over-current relay a. operates quick er with large large currents than than wit h small ones b. operates quicker with small currents than with large ones c. operates in the same time with any overload current d. e.
operates eventually even on currents less than the trip-setting value always operates instantaneously
11. An induction over-current relay has its time setting a adjusted djusted by means means of an index lever which is moved over a scale with graduations graduations numbered 1 to 10. Moving the lever from 10 towards 1 a. increases the time of operation operation on large overloads, only when the maximum current connection is used b. decreases decreases the time of operation operation on large overloads, only when the maximum current connection is used c. increases the time of operation on large overloads, only when the minimum current connection is used d. decreases the time of operation on large overloads, only when when the minimum curr current ent connection is used e. decreases the time of operation on large overloads, when any any current connection is used 12. In relay ttesting, esting, a cycle counter is u used sed a. to measure the frequency of the system voltage b. to d determine etermine tthe he number of ope operations rations of a re relay lay in a 24 hour period period c. to check the current required to operate a relay d. to check the tim e of operation of a relay e. to determine the operating frequency of an under-frequency relay 13. Series type motors for electrically driven rheostats have a split series field to a. change the directio n of rotatio n b. decrease the current consumption c. obtain low motor speed d. produce greater starting torque 14. A photoelectric relay system could not be used for which one of the following applications? a. controlling the temperature of a furnace b. amplifyi ng audio frequencies c. sorting objects of different sizes d. counting moving objects without physical contact 1.
The speed of a rotary conver converter ter in normal operation is governed by the frequency of the a.c. a.c. supply and the a. d.c. load b. number of poles c. a.c. voltage d. shunt field current
When a rotary converter is started on reduced a.c. voltage (from the a.c. side side), ), if the d. d.c. c. polarity of the rotary is reversed the operator should a. shut the machine down and re-start b. close the field switch “ down” unt il correct correct pola polarity rity is indicated indicated the then n close it in the “ up” position position c. close the field switch “down” and leave it in that position d. open the oil switch momentarily and then re-close it
The power factor of a synchronous con converter verter in normal operation will change from lag to lead if the a. load increases to a high value b. load drops to a low value c. field current is reduced to a low value d. d.c. bus voltage drops suddenly
The over-speed over-speed device on a rotary converter is usually arranged so that that when it operates operates it will open the rotary a. posit ive breake breakerr or swit ch b. oil switch c. negative breaker or switch d. oil switch and positive breaker or switch
One purpose for having dampers or amortisseur windings on rotary converter pole faces faces is to a. equalize the field strength b. provide a compound field c. minim ize hunti ng d. improve admission of cooling air
When an induction motor motor is mounted on the shaft o off a rotary converter for starting starting pu purposes, rposes, the motor usually has two less poles poles than the rotary. It is constructed this way a. b. c. d.
to stator winding sosimplify that its the synchrono us speed is high er than the speed of the rotary because it is smaller than the rotary to keep the starting current at a low value
The most likely cause for over-speed on a rotary in service is a. loss of A.C A.C.. power b. loss of D.C. power c. low A.C. frequency d. loss of field
When ro rotary tary brushes are prop properly erly adjusted, the cont contact act pressure pressure of the brushes brushes on the commutator will be a. greatest at the top brushes b. the same for all brushes c. smallest at the side brushes d. smallest at the bottom brushes
Weakening the field of a rotary operating in p parallel arallel with other rotaries will cause the a. brushes to spark b. D.C. output to increase c. Speed to decrease d. D.C. D.C. outpu t of this rotary to decrea decrease se
10. In case of a short circuit in the windings of a rotary converter, the dev device ice which limits the duration of the excessive A.C. current is the a. overload relay b. over-speed device c. transformer d. reverse current relay 11. The a. b. c. d.
simplest way to check the bearing of a rotary for excessive heating is by a thermometer feeling the housin g noting discoloration of the housing detecting odors
12. The a. b. c. d.
purpose of having the the armature of a rotary conv converter erter oscillate is so that that the brushes will wear evenly area of contact between brushes and commutator will be increased armature will be better ventilated commu tator will wear evenly
13. The interpole interpole (commutating) field winding of a rotary converter is usually connected a. b. c. d.
in series wit h the armature on the negative side in series with the armature on the positive side in parallel with the armature in parallel with the shunt field
14. A 3000 kw. rotary converter o operating perating at full load load with a d.c. voltage of 625 volts would deliver a direct current of a. 1875 amps b. 2083 amps c. 3625 amps d. 4800 amps 15. A piece of No. No. 1/9 emery cloth should be used tto o grind the commutator of a d-c motor a. whenever there is sparking at the brushes b. under no condition c. when the commutator is rough or worn d. when the brushes do not make good contact 16. a. A simple o off checking a commutator commutat or for tightness is to feel method the surface for uneven spots b. check one of the V-ring bolts with a wrench c. tap it light ly with a small hammer d. measure the diameter at several points 17. If high mica develops on a commutator, it is corrected by a. undercutting b. stoning c. shimming the copper
d. smoothing with sandpaper
18. Mica is commonly used in e electrical lectrical construction for a. commu tator bar separators separators b. switchboard panels c. strain insulators d. heater cord insulation
1. What is the equivalent of a safety valve used in a pressure container versus the one used in am electrical circuit. a. switch b. bushing c. fuses d. valve 2. If a short circuit occurs in an electrical system what happens to a fuse or a circuit breaker? a. It will continue to operate b. It will blow c. It will open the circuit d. It will be short circuited 3. What type of fuse is designed primarily for motor circuit protection.? a. dual element fuse b. cartridge type c. relay type d. coil type 4. Name the particular kind of fuse designed for electrical circuits and capable of producing high fault current. a. dual element fuse b. restriking fuse c. current limiting fuse d. Disconnect
5. Power fuse are designed for use in what electrical system? a. High voltage distribution system b. High power distribution system c. High current transmission line d. Sub-transmission system 6. What is the most common source of electrical fault in an industrial plant? a. Insulation failure b. Arcing c. Malpractice
d. Inrush current
7. Time delay in a circuit breaker is provided by the use of what kind of element? a. magnetic strip
b. bi-metallic strip
c. arcing strip
d. dual strip
8. What is the maximum number of conductors permitted in wireways, and what is the maximum percentage of fill a) 30, 20% b) 20, 30% c) 25, 40% d) 30, 30% 9. Two conductors in a conduit, what is the allowable fill? A. 31 % b. 40 %
c. 53 %
d. 60 %
10. Splices may not occupy more than ______% of the cross- sectional area in the auxiliary gutter a) 75% b) 50% c) 70% d) 60% 11. Conductors supplying two or more motors shall have an ampacity equal to the sum of the full load current rating of all the motors plus _______ % of the highest rated motor in the group. a. 25 b. 80 c. 100 d. 125 12. What do you call an entire assembly of device that controls and protect machine or circuit? a. switch b. bushing c. fuse d. switchgear 13. Two 120 v small appliance circuits are connected, one connected line to neutral and one connected line two to nuetral. One line has 1000 watt load on it and the other line has 1200 watt load on it. With both loads turned on what would be the wattage in the neutral. a. 2200 b. 1200 c. 1000 d. 200 14. What is the fault current that a circuit breaker can interrupt without damage to itself called? a. Momentary capacity b. interrupting capacity c. rapturing capacity d. instantaneous
15. The normal fluorescent lamp is designed for operation at _______F° _______F ° a) 50 b) 20 c) 30
16. Which of the following is the best way to eliminate stroboscopic effect a) Using new luminaires b) using 400 Hz c) used flat chord
d) using 500 v
17. If the full load current of a 2 hp 115 v single phase motor is 24 amps, the branch circuit protection to this motor should not be set a more than _____ amps using dual element time delay fuses. a. 30 b. 40 c. 60 d. 80 18. The resistance of made electrode should not exceed _____. a) 25 Ω b 30 30Ω Ω c) 40
d) 50 50Ω Ω
19. In a group of four motors, one motor draws 10 ampere, one draws 45 ampere and two draws 75 ampere. What size of conductor must be used for the feeder circuit? a) 224 A b) 228 A c) 300 A d) 124 A 20. How many overload relays are required to protect a three phase motor circuit? When instantaneous trip breakers are used in a three phase branch circuit, how many overload protections are required r equired by the code?
21. A conductor encircling a building and interconnecting all ground terminals a) counterpoise b) Faraday cage c) electrode
22. A pendant fixture is a. hanging
c. bracket 2
23. Arrester grounding conductor should be _______ mm Copper and _____mm Aluminum a) 2, 3.5 b) 5, 4 c) 2.5, 5 d) 6.5, 5 24. Size of pull boxes is less than ______ times the diameter of the largest raceway a) 8 b) 6 c) 5
25. The voltage change resulting from motor starting a) voltage swell b) voltage sag
d) voltage drop
c) voltage dip
26. A compartment or chamber to which one or more air ducts are connected and which forms part of the air distribution system a) Rosette b) Hickey c) Plenum d) mast 27. Any motor application shall considered as ____ unless the nature of the apparatus it drives is such that the motor will not operate continuously with load under any condition of use. a. short time duty
b. varying duty
c. continuous duty
d. periodic duty
28. A 10 Hp , three phase, 480 v squirrel cage induction motor draws 15 ampere at full load. What size of dual- element time non time fuses are required to protect the feeder and ampacity of the fuses? a. 31.5 A b. 45.8 A c. 28.25 A d. 14.5 A 29. Which one is the type of temperature detector used in motor windings? a. thermostat b. resistance c. thermocouple
30. A tool that is used to aligned vitrified tile conduit in multiple ducts is a a. mandrel b. Neil c. hickey
31. The definition of ambient temperature is a. the temperature of the conductor b. the insulation rating of the conductor c. the temperature of the area surrounding the conductor d. the maximum heat the insulation can be used within 32. The ampacity of a # 250 kcmil IGS cable is _____amperes. a. 119 b. 168 c. 215
33. branch circuit. What should be the maximum allowable rating o off a cord and plug connected load? a. 15 ampere b. 20 ampere c. 30 ampere d. 24 ampere 34. The service disconnecting means for each service-entrance conductors must consists of not more than ________ switches s witches or _________ circuit breakers mounted in a single enclosure, e nclosure, a group of separate enclose or in or on a switchboard? a. 5 and 4 resp. b. 6 and 5 resp. c. 6 and 6 resp. d. 4 and 5 resp. 2 35. What is the current carrying capacity of each conductors if 36-8.0 mm THWN copper conductor are install in an auxiliary gutter? Considering one 8.0 mm2 THWN has an ampacity of 50 Amp. a. 30 amp each b. 40 amp each c. 50 amp each d. 45 amp each
36. What is the maximum allowable distance interval between supports securing busways? a. 1,000 mm b. 2,000 mm c. 1,800 mm d. 1,500 mm 37. A short circuit occurs in a branch circuit fused at 20 A and the conduit is well grounded. How long will the voltage appears at the conduit. a. Only for a time it takes to blow the fuse b. after a few minutes c. at the instant of fault d. momentarily 38. What is the average insulation resistance in a power system? a. 1 to 10 mega ohms b. 100 ohms c. 100 Kilo ohms
d. 25 ohms
39. Which of the following statements on wiring in commercial garages and shops is NOT correct. Which one is this? a. The ground conductors conductors shall be connected to the ground terminal of the utilization equipment b. Receptacles attachment plugs and similar devices shall be of the polarized c. Lamps and lamp holders for fixed lighting that are located above vehicles shall be installed not lower than 3.5 mm d. Battery charges and batteries being charged shall no be located in location classified as hazardous. 40. A 3φ 3 φ motor draws 50 amperes amperes at full-load. What shall be the m maximum aximum inverse time breaker th that at may be used for short circuit protection? a. 50 amp b. 100 amp c. 125 amp d. 75 amp 41. Lead wires furnished as part of a weatherproof lamp be stranded and rubber covered and approved for such service, shall not be less than, what wire size? b. 2.0 mm2 c. 0.75 mm2 d. 5.5 mm2 a. 3.5 mm2 42. The best way to test a capacitor when used in a 115 V electric motor is by_________. a. bridging b. voltmeter c. spark test d. all of these 43. Gutters shall be supported throughout their entire length at suitable intervals preferably not exceeding a. 500 mm b. 1000 mm c. 1500 mm d. 2000 mm
44. The maximum number of over current devices, other than those provided for in the mains of a lighting and appliances branch circuit panel board in any one cabinet or cut-out box is a. 36
45. A hickey is_____________________ a. a tool used to bend small sizes of rigid conduit. b. a part of a conduit c. not used in the electrical trade. d. Used only by a plumber 46. Equipment for hazardous locations shall be approved for the following property, EXCEPT a. durability b. combustibility c. ignitability d. explosibility 47. A minimum space of _____ mm between the top of any switch board and any combustible ceiling must be provided a. 1300 b. 1100 c. 1000 d. none of these 48. Which of the following is not the standard ampere rating for fuses and inverse time delay circuit breaker? a. 100 A b. 150 A c. 120 A d. 90 A
49. The minimum size of wire wire used in electrical wiring is the former number 14 AWG. Under the metric system now shown the new PEC, the diameter is, a. 1.6 mm b. 2 mm c. 2.6 mm d. 3.2 mm 50. There shall be no more than ____, _____ ° bend in the conductor a. 4, 180 b. 10,45 c. 4, 90
d. 3, 180
51. A lighting fixture shall be wired with a fixture flexible cord with a cross-sectional area of NOT less than _________ mm2. a. 0.50 mm2 b. 2.0 mm2 c. 1.23 mm2 d. 0.75 mm2 52. When conduits, or other raceways, enter a switchboard or floor standing panelboard, the minimum wiring space between bottom of enclosure and non insulated bus bars, their supports or other obstruction is _________ mm. a. 200 b. 205 c. 255 d. none of these 53. PEC requires that the resistance to ground of a single electrode consisting of rod, pipe or plate shall be…. a. 30 Ω to 50 Ω b. above 100 Ω c. 25 Ω or less d. 50 Ω to 100 Ω 54. The underground service conductors between the street main, including any risers at the pole or other structure or from transformer and the first point of connection to the service entrance conductors in a terminal box. The point of connection is considered to be the point of entrance of the service conductors into the building. a. Service drop b. Service lateral c. Service entry d. Service Raceway 55. The rigid metal conduit, electrical metallic tubing, or other raceway that enclose service entrance conductors. a. Service Drop b. Service Raceway c. Service Entry d. Service Lateral 56. Is a device for the protection of personnel that function is denergize a circuit or portion thereof within an establishment period of time when a current to ground exceed some predetermined value that is less than that required to operate the over-current protective device of the supply circuit a. circuit breaker b. surge arrester c. Ground fault circuit interrupter d. all of these 57. The PEC rules on Fire Protective Signaling Systems cover the installation wiring and equipment up to what maximum voltage? a. 150 volts
b. 300 volts
c. 750 volts
d. 600 volts
58. For distribution lines supported on poles and installed above communication conductors, the horizontal clearance necessary to provide climbing space shall NOT be less than what minimum distance? a. 500 mm b. 1000 mm c. 600 mm d. 760 mm 59. An Enclosure use to connect flexible cord to permanent wiring a) Pull Box b) Rosette c) Damper
60. As compared with solid wire, stranded wire of the same gauge size is. a. better for higher voltage b. given a higher ampacity c. easier to skin d. larger in total diameter 61. Mica is commonly used for. a. pole insulator
b. commutator bar separator
62. Safe value of current that human body can tolerate not greater than _________ sec. is _______ mA
a) 3, 9
b) 9, 3
c) 6, 6
d) 3, 6
63. The codes specifies that one equipment is “in sight from” another equipment if it is visible and at a distance of: a. not more than 15 meters b. not less than 15 meters c. not more than 15 meters d. not less than 15 meters 64. An assembly of two piece of insulator provided with grooves for holding one or more conductors at a definite spacing a) Raceway
65. Additional circuit derived from existing circuit without the use of additional wire a) Derived circuit b) Ratchet c) Hickey Circuit 66. If potential exceeding ______ v ,warning signal shall be displayed a) 500 b) 400 c) 600
67. Min headroom of a working space about service equipment, switchboard or motor control shall be ______ mm a) 1000 b) 1500 c) 1900 d) 1700 68. Gas manufacturing plant where flammable gases may escape is considered as; a. Class I, Division 1 area c. Class II, Division 1 area
b. Class I, Division 2 area d. Class II, Division 2 area
68. Support of AC cable should have an interval not exceeding a) 1300 b) 1000 c) 1500
69. The service or feeder capacity necessary to provide for six 5 kW clothes dryer is a) 30 kW b) 37.5 kW c) 53 kW
d) 21 kW
70. Metal enclosed equipment located outdoor accessible to general public and the bottom of enclosure is less than _____ mm above the floor a) 2000 b) 2500 c) 2700 d) 1300
71. Wiring methods that should not be used on theaters, commercial garage and other similar location a) Concealed knob and tube work b) Wireways c) Busways d) Metal raceway 72. Wireways and Busways shall have a support of not less than _________ mm or _________ mm in case of vertical runs. a) 1500, 4500 b) 3000, 1500 c) 4500, 1500 d) 1300, 1900 73. What is the minimum distance of a laundry outlet from the appliances a) 1800 mm b) 2000 mm c) 2500 mm
d) 1000 mm
74. Hallway ___________ mm or more must have at least one outlet. a) 1000 b) 2000 c) 3000
75. A column pole or narrow base structure that support overhead conductor through its crossarm a) Creosote b) stockyard c) spool d) Mast
76. If the problems is extensive and requires more time for checking and for computations of fees, the issuance of electrical permit need not be issued immediately. The delay shall not be longer that _______ working days after which time the application together with the accompanying plans shall be considered as complying with all the requirements and the electrical permit shall be issued immediately thereafter. a) 10 b) 5 c) 7 d) 15 77. This type of cable is fabricated assembly of insulated conductors enclosed in a flexible metal sheath. a. ground wire c. medium voltage cable
b. integrated gas spacer cable d. armored cable
78. The rating of the overcurrent device shall not be less than the continuous load plu a percentage of the continuous load. a. 125% b. 80% c. 100% d. 140% 79. In concealed knob and tube wiring, the clearance to be maintained between conductors is. a. 55 mm b. 45 mm c. 76 mm d. 50 mm 80. for optional calculation in dwelling units, the first 10 kw shall be computed at 100% while the remainder is at_____. a. 65 % b. 60 % c. 50 % d. 40 % 81. What is the maximum number of conductor’s permitted in wireway’s at any cross section, signal circuit or starter – control wires are not included. a. 25 conductors b. 30 conductors c. 40 conductors
d. 50 conductors
82. When circuit breakers are installed in enclosed switchboards, they are usua usually lly derated to a certain percentage. What is this percentage? a. 60 % b. 80 % c. 50 % d. 70 % 83. In hazardous location, the use of non-metallic conduit shall be permitted provided it is buried not less than______ below the earth level. a. 400 mm b. 600 mm c. 1,000 mm d. 500 mm
1. What does GFCI stand for? A. conduct conducting ing index C. Ground Ground fault fault circuit index
B. Ground fault circuit interrupter D. None of the above
4. Which of the following colors is acceptable for a neutral wire? A. Black C. Green B. White
5. If you were buying a motor which of the following is the best insulation class? A. A B. B C. H D.F
6.Which of the following motors has a capacitor? a. Complusion start induction run b. universal
c. permanent permanent spli t
7. Which of the following is not a advantage of a electric motor. a.low initial cost c.no exhaust b. easil easil y portable
10 What percent of the theoretical RPM is the Actual RPM of a motor?? A. 50 B. 1 C. 4
11. If a capacitor is wired in the running windings what type of capacitor would it be? A. Dry B. Wound C. Wet D. Shaded 12. What color is not appropriate for the grounding conductor? A. Red B. Green C. Bare D. Green w/ Yellow Stripe 13. What type of motor works with both AC and DC power? A. Repulsion Start C. 3-Phase B. Universal
D. Written Pole
14.Which motor doesn't have a Centrifugal Switch? A: Split-phase start induction run B: Capacitor start Capacitor run run C: Capacitor start induction run D: Permanent Permanent Split
15. Which motor doesn't have a capacitor? A: Spl it -ph ase s tar t i nd uc ti on ru n
B: Capacitor start Capacitor run
C: Capacitor start induction run
D: Permanent Split
16. Which motor has both capacitors, wet and dry? A: Split-phase start induction run B: Capa Capacitor citor start Capacitor Capacitor run C: Capacitor start induction run D: Permanent Split 17.What is the duty rating of a motor A. Ti me B. Speed
18.A ground wire color should be A. Green B. Bare
C. Split Phase
C. Green with yellow stripes D. All of the above
19. What type of lubricant should be used on electric motors: A. WD-40 B. Hydraulic oil C. Non-detergent Non-detergent t ype oil D. Bar & chain oil
20. An example of a piece of equipment a shaded pole electric motor would be found is: A. grinder B. box fan C. jig saw D. drill 22. The grade of oil that should sh ould be used for a 2hp motor is: A. 10 B. 15 C. 20
23.Dry capicator covers are usually made of what material? A. steel C. rubber b. plastic
24. What percentage drop of current is safe for electric motors? A)10%-12% B)8%-9% c)around 5%
25. If a motor has a service factor of 1.25, you can safely overload the motor by? A. 2.5% b.25% C.75% D. 25% 28. A motors life is reduced by one-half for every ___ degrees Celsius? a. 1 b.5 c.10 d.20 30. From the slide show on electric motor maintenance, why should you remove burs from f rom the shaft? a. because they are ugly b. because they collect dust c. so you don't scar the bea bearings rings d. you should not remove any buurs
31. What is different about UF cable and NM cable? b. UF cable is insulated, NM is not a. UF cable has paper in between wires c. NM cable has paper in between wires d. nothing is different 32.. When wiring a duplex receptacle the hot wire is attached to what color screws? a. copper b. green d. orange c. silver
34. which of the following is not recommended when mounting a service entrance in a live stock area/ a. mount outside if needed to keep away from dust etc. inside b. mount to wall with fire resistant material between wall and service entrance e ntrance c. recess recess into w all for better insulation 35. What size breaker should be used when using 10 guage wire? a. 10 amp. B. 20 amp. C. 30 amp.
D. 40 amp.
36.What kind of electric motor has starting windings, 1 wet capacitor, no centrifugal switch and a squirrel cage rotor? a. Capacitor start/Induction run. B. Permanent Permanent spl it c. Universal d. 3 Phase
37. What would be the most appropriate motor to use in a situation in which there was a hard starting load that needed variable speed capability? capabilit y? b. Synchronous c. Repulsion d. Capacitor start/Induction run a. Universal 38. What motor has starting windings, a centrifugal c entrifugal switch, does not contain a capacitor, cap acitor, and a squirrel cage rotor? a. shaded pole b. 3 phase c. universal d. split phase
39. When sizing the wires that t hat extend the power form the source to the disconnect for the electric motor, the conductors should be sized at ______ percent of the full-load current o off the motor. A. 115 percent B. 120 percent C. 125 percent D. 250 percent
40. Which of the following is used in a clock? A. Split phase start B. Shaded pole
C. Synchrono us D. Capacitor start
41. What type of motor has a dry type capacitor? a. universal motor b. capacitor start induction run d. capacitor start capacitor run c. repulsion repulsion start induction r un 42.What type of motor is used in electric e lectric drills and other power hand tools? a. split phase start induction run b. capacitor capacitor start i nduction run c. universal motor
d. capacitor start capacitor run
43. Which of the following electric e lectric Motors doesn't have a cent Switch? a. Split Phase Start B. Capacitor Start C. Capacitor Start/run D. Shaded pole 45. If a capacitor is filled with oil it is... Hermetically Sealed B. Electrolitically Sealed C. Circuitry Sealed D. Filled with Paper 47. a capacitor start/ start/capacitor capacitor run motor has what type of capacitors a. electrolytic (paper)/ hermetically (oil) sealed sealed b. electrolytic/electrolytic c. hermetically sealed/ electro electrolytic lytic d. one electrolyt electrolytic ic capacitor only 48. which choice is NOT a rule when sizing a device box? a. a wire not spliced counts as one wire b. a wire that terminate terminates s in a box counts as one wire c. a wire contained within a box counts as one wire d. all grounded wir wires es count as one wire A device box with: 1 hot wire, 1 neutral wire, 4 clamps, 2 grounding grounding conductors, and a duplex receptacle, would be sized for how many wires? a)4 b)5 c)8 d)10 3)which of the following is not a characteristic of universal series motors? a)can operate on ac or dc current b)rapid acceleration c)capacitor start d)no fixed speed 2. What does NEMA stand for? A. National Electric Mechanics Assoc. B. Never Exactly Motivated Assoc. Assoc. C. Nation Nation al E Electric lectric Manufacturers Assoc. D. National Energy Machines Assoc. When reading the nameplate on an electric motor you see the frame number for that particular motor is 60, this means the horsepower of the motor is... A. Greater than or equal to 1 hp. B. Fractional hp. C. 5 hp. D. 2 ½ hp. 2. If Joe could add a set of poles to his electric motor, the speed of the rotor would... A. Increase B. Not change C. Become variable D. Decrease
3. A. C.
Soft-Start motors are used most commonly when? Fractional hp. is desired B. A moto r larger than 5-7 hp. is needed needed Installed in a drill, grinder, router, etc. D. Cost is a concern
1. What is the name for the oil-sealed capacitor in a capacitor start, capacitor run motor? closed capacitor B. vacuum sealed capacitor C. hermetically sealed sealed ca capacitor pacitor 3. A centrifugal switch can be found in which of the following: shaded pole, universal, and permanent split cap. motors phase, repulsion start, and shaded pole motors C. Split phase, cap. cap. start, and ca cap. p. start/cap. run m otors
A. B. Three
1) A shaded pole motor would be found where? A) Electric Drill B) Tractor starter C) Air compressor D) Box Fan 3) If you do not know what type of motor is found where, what should be your base answer? ans wer? A) Log Splitter B) Ceiling Fan C) Bio-diesel D) Split-Phase What type of motor is generally used when 5 or more HP is needed? A. Shaded Pole B. Synchronous Motors C. Soft-Start Soft-Start Motor s D. Written Pole When looking at four wires coming from an electric motor, how can you tell which two wires are connected to the starting windings? A. the starting windings will be yellow or bare B. the wires for starting wi nding w ill have a higher ohm reading C. the red wires go to running windings D. all four wires are connected to the starting windings
If you had a motor with four dangling wires, how could you determine which two wires were connected to the starting windings? A. All four wires are connected to the starting windings B. The starting windings would have green or red wires C. The two wir es for the starting win dings w ould show a higher ohm reading than the running windings D. The motor must be taken apart to determine which wires go to the starting windings 2) How many classes of insulation are there in electric motors. a) 2 b) 3 c) 4
Q 3) In a fraction hp electric motor, m otor, how much of the full load current of the motor should the switch be. a) 100% b) 125% c)175% d) 200%
Which motor is most commonly used in a drill. A Written pole motor B Three Phase motor C soft-start motor D Universal Motor For how many degrees celsius increase does it take to cut the life of the motor in half? 5 degrees 20 degrees 15 degrees 10 degrees 1. Which is not a factor that controls strength of induced voltage? a. strength of magnetic field. b. length of conductor in field. c. size of cond uctor in f ield. d. speed at which the conductor moves m oves
2. Which in not one of the basic components of Power Transmission? a. power generation facility. b. increasing transformer(substation) transformer(substation) c. high voltage transmission lines d. increase transfor mer(substation) 1.The circuit created by the Stop switch s witch on the Stop/Start Switch is referred to as the: A) Temporary Circuit B) Memory Circuit C) Kill Circuit D) Common Terminal 2. To produce 60Hz current, a generator must run at: A) 2400 RPM B) 3600 RPM C) 1800 RPM D) BOTH A & C 3) Which of the following is normally the most expensive means of producing power: A) Hydroelectric B) Natural Gas C) Coal D) Wind Power Which of the following is not a characteristic of motor starters. a. rated rated in w atts b. manual-coil and control activated c. manual-hand activated d. single pole Which of the following is not a NEMA rating for enclosures. a. general purpose(dry and free of dust) b. Weather resistant C. water tight d. not water tight
When sizing branch circuits, the percentage of the current load circuit should be a. 90% b. 100% c. 125%
The ampere rating on a snap switch is what if the full load current of the motor is 7.2 amps? b) 28.4 c) 7.2 A) 14.4 am ps
How many circuits are in a magnetic motor controller? a) 4 b) 1 c) 2
2. NEMA for enclosures watertight and dustight outdoors andWhich in, and is also a lsorating corrosion resistant?is watertight a. 2 b. 4X c. 3 d.
3. How many kW of generator is needed per bhp of the lar largest gest motor when sizing a generator? a. 3 b. 6 c. 10 d.
When using a snap switch the ampere rating must be ___________ the full-load current of the motor. A. 115% above B. 2 times C. 125% above D. 15 amps over 2. Start stations are... A. wired in series B. used with 3 phase power only C. wired in p arallel D. rarely used and have become obsolete 3. Double-pole double throw switches are located A. on the generator B. near the house C. on the meter pole D. beside the breaker box 2. In a magnetic controller, which lines li nes are fused? A. Green B. Pink C. Blue D. Black 3. What is an advantage of a relay? A. Very cheap B. DC Power is used C. It will not overheat a motor D. It stores power to st art a motor that has a large starting starting requirement
1. Static type phase converters are are preferred for which of the following? a) for single 3-phase mot motor or b) if operated operated continuously c) if operated for short periods d) All of the a above bove 5. Which of the following devices will protect an overloaded circuit? a) Bi-metallic strips b) Ratchet-pawl device c) Fuse d) None of the above e) All of the above 1. Which of the following are types of enclosures NEMA uses ffor or ratings on electromagnetic controllers? a. watertight
b. corrosion resistant c. dry and dust free d. all of the above. What type of fuse is triggered by heat? a. single b. double c. Bi-metalic d. prong
23. In order to control a lamp from 3 locations, you need a. three 2-way switches. b. three 3-way switches. c. one 2-way and two 3-way switches. d. two 3-way 3-way and one 4-way swit ches.
1. What is the NEMA raiting in volts for a locking receptacle? a. 125-347 b. 125-600 c. 10-150 d. 500-550 2. What is the benchmark on ohms for a grounding conductor? a. 30 ohms b. 100 ohms c. 25 ohms d. 75 ohms Answer : 25 ohms 3. What lenght if copper rob should be used for a gorunding conductor? a. 10 ft b. 3 ft c. 20 ft d. 8.5 ft 2. A SWITCH THAT IS USED TO TURN ON LIGHTS IN A ROOM SHOULD BE MOUNTED THIS DISTANCE FROM THE FLOOR TO THE CENTER OF THE SWITCH? A 1 FOOT B 40 INCHES C 48 INCHES D 52 INCHES 3 AN ACCEPTIBLE VOLTAGE DROP FOR AN ELECTRIC MOTOR IS? A 2-3% B 4-5% C 5-6% D 6-7%
3)How many feet do you need to sufficiently ground to a water pipe? A)5 B)10 C)15 D)20 4) How long must the grounding ring ri ng of bare copper be? A. 15 ft B. 18 ft C. 20 ft D. 50 ft 2. How big should the disconnect be for an electric motor? A. 115% o f f ul l c ur ren t l oad B. 100% of full current load C. twice full current load D. half full current load 2) Using aluminum is a good option if you you remember tto o A) Always tighten all attachments as much as as possible to reduce the chance of them coming apart B) Limit t he a amount mount of t emp. variations to keep the metal from warping C) Use backwiring a as s much as possible 3) Copper Clad Aluminum wire is different from from Aluminum wire in that it A) Has more insulation around the wire B) The copper w wire ire is coate coated d with aluminum C) Can only be used in livestock operations D) Is rate rated d the same as as pure copper wi re
Which of the following switches is suitable for use if the motor is 2 horsepower and operates at 120 volts? A. Plug and receptacle B. Circcuit Breaker C. breaker D. Time Snap delay Snap swi tch The type of switch that should be installed to prevent injury with a standby power unit to others is: A. Single pole, double throw switch B. Double Double pole, double throw sw itch C. Double pole, single throw switch D. Single pole, single throw switch
2. Portable hand tools do not require a grounding conductor if a. it is not being used in damp places. b. it is only used on two wire receptacles.
c. it h as a double insu lated case. d. it is a circular saw.
3. Which of the following is not an acceptable system ground? a. underground water pipe b. metal frame of a building c. a concrete encased electrode d. a fence post driven into t he ground
1.) The best method for tightening down aluminum alum inum wire is A. Tighten as hard as you can B. Tighten till it gets tough and then go another half turn C. Use Use a torque w rench d. None of the above
2) In number of ohms, what is the benchmark for grounding resistance? a) 65 b) 25 c) 40 d) 10
1. Which portable appliance(s) must be grounded? A. B. C. D. E.
Dryer Washer Dishwasher All of the above None of the above
3. This type of wire should be used when grounding in corrosive environments: a. copper b. brass c. aluminum d. none of the above 1. Double insulated hand tools: A) Require a 3rd plug B) Need at least 240 volts to operate C) Are not required to h ave the 3 3rd rd plu g D) Are no longer sold due to safety hazards 3. If a second electrode is needed, n eeded, it should be placed: A) B y t he s erv ic e ent ra ranc nc e B) Minimum of 2.5' underground C) By the transformer D) Near a water line 3. When using aluminum wire all of the below should be considered EXCEPT A. proper tightening of wire at terminals B. use in 3 phase situati ons
vibration hard drawn AL
1 What is the correct size and depth of a grounding rod? A 4' 1/4" rod B 8.5 8.5'' 1/2 1/2"" rod C piece of need wire in grou ground nd will suffice D Doesn't tothe be grounded 2 What are the qualifications for a grounding water line? A 10' in length B Underground C Metal D All are necessary requirements 3. What is the max. size amp a mp rating protects a 12 gage wire? A. 20 amp B. 15 amp C. 30 amp D. 12 amp 1. A. B. C. D. E.
Stray voltage can be referred referred as Tingle voltage Neutral to earth voltage Extraneous voltage Neutral to ground voltage All of the above is correct
2. When using fluorescent lighting in a machine shed without h heat, eat, which type of ballast would be best A. Normal indoor ballast B. Instant start ballast C Cold start ballast D. Not using a ballast 3. When wiring up lighting for a farm shop shop,, what is the best use of switches. A. One switch for all the lights in the shop B. Separate switches for each light C. Sprat swit ches for ea each ch row of lights D Wire lights up directly and avoid using switche switches s Which of the following is not a cause of aluminum wiring failure? a. improperly tightened connections b. using old, hard drawn aluminum c. low ambient t emperatures emperatures d. corrosive or high moisture areas Why it is important to have exterior floodlights and 1-20 Amp fuse for trouble lights near a harvestore/silo unloader. a. so you can se see e to make repairs repairs b. so you can load feed in the dark c. safety d. all of t he above
How far off the ground(min) must a electrical line li ne be streaching from the pole to a shop, if it goes over the yard? a 8' b 10' c 12' d 14" What type of electrical wire must be used to wire up a confindment building? a AU b UF c OF d none of the above
3. when determining a device box size, which of of the following is a rule? a. each strap counts as one wire b. a hickey does not count as one wire c. fixture stud is not counted as a wire d. cable clamp(s) are counted as one wire e. only a and d
Which one of these is not correct? A. Sw it ch es m us t b e pl aced 4 feet fr om th e fl oo r t o b ot to m o f s w it ch B. Outlets must be 12 inches to center C. Between outlets must be 6-8 feet.
2) If an electric motor operates operates at 10 degrees hotter hotter than normal what will happen? a) b) c) d)
It will let the smoke out It will draw more power and blow a fuse It will cook hotdogs w while hile you wait It will shorten its life by ha half lf
3) An switch in a room should be located how high? a) b) c) d)
High enough so that that small children cannot reach them Low enough so that you can reach them with your feet A hammer handle length above the ground 48 inches
2. Outlets should be placed... A. 6-8 ft apart B. 12 in. from floor C. Every 2 ft of wall space D. All of t he above
3. When sizing up the Main service the 2nd largest load should be calculated using which demand factor? A. 65% B. 70% C. 75% D. 100%
1. Which of the following is a factor tthat hat affects resistance of wir wire. e. a. insulation b. temperature c. installing d. all of the above 2. What color is normally considered to be the "hot" lead? A. White B. Blue C. Black D. Red
3. What is the maximum percentage voltage drop allowable al lowable through an extension cord? a. 1% b.2% c.4% d.6%
3 What is the color of the neutral wire A green B white C D Red Black
1. when sizing the main for all buildings the demand factor for the residence is what percent? 100% 75% 50% 25%
2. in lighting and general purpose circuits with 8-10 outlets what is the smallest gauge wire that is acceptable to code? 10 gauge 6 gauge 12 gauge 16 gauge
2. How many amps can can a 10 gauge wire handle? A. 10 B. 15 C. 30 d. 100