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What is the name of a direct-indicating instrument for measuring resistance? | nec_codebook |
What is the name of the very sensitive instrument used to measure these small variations? | nec_codebook |
Which of the following instruments are used to measure temperatures? | nec_codebook |
When taking low-current readings with a clamp-on ammeter, what device is normally used to help get a more accurate reading on the ammeter scale? | nec_codebook |
What is another way to multiply the current reading on an ammeter's scale when a current multiplier is not available? | nec_codebook |
If the actual current drawn by the motor is 5 amperes, what will the meter reading be? | nec_codebook |
How should a voltmeter be connected in a circuit to take a voltage reading under normal conditions? | nec_codebook |
If a voltage test is made at the main disconnect on a 120/240-volt, three-phase, 4-wire delta system; what should the voltage be between any two ungrounded conductors? | nec_codebook |
What will the voltages be between the grounded conductor and any ungrounded conductor? | nec_codebook |
If the service in Question 8-22 is supplied by a utility company, and the voltage reading at the main service equipment is below 230 volts, who is usually responsible for correcting the low-voltage problem? | nec_codebook |
If a voltage reading is taken between any two ungrounded conductors on a 120/208-volt three-phase, 4-wire Y-Y-connected electric service, what should the normal voltage reading be? | nec_codebook |
In the electric service described in Question 8-25, what is the voltage between the grounding conductor and any phase conductor? | nec_codebook |
If a voltage reading is taken at the main service disconnect for the electric service in Question 8-25 and found to be approximately 208 volts between any two ungrounded conductors, but the same voltage test shows only 190 volts at the last outlet on the circuit, where does the fault lie? | nec_codebook |
If voltage readings are taken on a three-phase, 4-wire, 240-volt, delta-connected electric system and show a reading of 230 volts between phase and ground and the service and two of the this problem, what is the probable cause of the third shows a reading of only 50 volts between phase and ground? | nec_codebook |
When cartridge fuses are tested with a voltmeter, how should they be tested? | nec_codebook |
If the ratio of watts to volt-amperes in a DC circuit is always at unity, what is the relationship between them? | nec_codebook |
When solving a low-voltage problem on a circuit, what is the first step to take with the voltmeter leads? | nec_codebook |
How can a DC voltmeter be used to measure a low resistance in a de-energized AC circuit? | nec_codebook |
If a tachometer measures the revolutions per minute of a revolving object or machine, in what unit is its output calibrated? | nec_codebook |
What is a good indication that an open circuit exists? | nec_codebook |
What visual test can be performed on a clear, incandescent lamp to determine if it is good or not? | nec_codebook |
How can a frosted incandescent lamp be tested when no means of electric current is available? | nec_codebook |
If testing a load center with the main disconnect open using a faulty fuse, what reading would an ohmmeter show? | nec_codebook |
What conclusion can be drawn if the ohmmeter shows any resistance at all when testing a load center with the main disconnect open? | nec_codebook |
What is the basic definition of a short circuit? | nec_codebook |
When testing conductor insulation with a megger, what is the desirable voltage level in relation to the peak value of the rated AC voltage? | nec_codebook |
What is the typical voltage range provided by most meggers for insulation testing? | nec_codebook |
In general, what are the three basic electrical faults? | nec_codebook |
If a plug fuse window appears clear and the element is merely broken, what is the probable cause of the fuse blowing? | nec_codebook |
If a plug-fuse window is blackened or discolored, what is the most probable cause of the fuse blowing? | nec_codebook |
To test an ammeter for accuracy, another ammeter of known accuracy can be connected in the circuit with the ammeter under test. How should these ammeters be connected? | nec_codebook |
If the ten 100-watt lamps are connected to a 118-volt source, what should the reading of both ammeters be? | nec_codebook |
What is the purpose of the independent switches in the test circuit? | nec_codebook |
If the phase-to-neutral voltage in a three-phase system is 2400 volts, approximately how much is the phase-to-phase voltage? | nec_codebook |
What principle do induction motors utilize? | nec_codebook |
What are the two main parts of an induction motor? | nec_codebook |
What is the primary winding of a transformer equivalent to in an induction motor? | nec_codebook |
What are the stator and rotor of an induction motor sometimes referred to as? | nec_codebook |
What is the common function of controllers used in electric motors? | nec_codebook |
What are some components that can be found in motor controllers? | nec_codebook |
What are induction motors used for in terms of horsepower range? | nec_codebook |
According to the text, what are few electrical systems that do not use electric motors? | nec_codebook |
If a motor controller also serves as a disconnecting means, what must it do? | nec_codebook |
What must a disconnecting means for a 2300-volt motor be capable of being locked in? | nec_codebook |
Each continuous-duty motor rated at more than what horsepower must be protected against overload by an approved method? | nec_codebook |
Where the NEC specifies that one item or piece of equipment shall be in sight from, within sight from, etc. of another item or piece of equipment, they must not be more than how many feet apart? | nec_codebook |
Which of the following statements about liquidtight flexible metal conduit is/are correct? | nec_codebook |
If a conductor is covered, what does it mean? | nec_codebook |
A power factor correction capacitor connected on the load side of the overload device of a motor reduces the line current by 20%. If the full-load current of the motor is 100 amperes, what is the new current after the reduction? | nec_codebook |
Conductors supplying two or more motors must have an ampacity equal to the sum of the rating of all the motors plus what percent of the highest rated motor in the group? | nec_codebook |
What may the locked-rotor current be assumed to be for small motor-compressors not having the locked-rotor current marked on the nameplate? | nec_codebook |
What is the maximum overcurrent protective device allowed on a 480-volt branch circuit load of each motor is 5 amperes? | nec_codebook |
What is the maximum amperes rating for a 240-volt single-phase room air conditioner to be considered as a single motor unit? | nec_codebook |
Unless identified for a different value; motor control circuit devices with screw-type pressure terminals used with No. 14 AWG or smaller copper conductors must be torqued to a minimum pound-inch value. What is this value? | nec_codebook |
What must be used at all openings in an enclosure, conduit box, or barrier where wires pass through the opening in motor circuits? | nec_codebook |
What is a protective device for limiting surge voltages by discharging or bypassing surge current and also preventing continued flow of follow current called? | nec_codebook |
What is a phase converter, an electrical device that? | nec_codebook |
When using a phase converter for a fixed load where the input and output voltages are the same, what percentage of the full-load current must the single-phase conductors have an ampacity not less than? | nec_codebook |
If the motor and its controller must have an ampacity not less than what percent of the full-load secondary current? | nec_codebook |
If a motor uses a cord and plug as a disconnect, what must the attachment plug be rated for? | nec_codebook |
If three three-phase motors are connected to a 120/240-volt single- to three-phase converter with a rating of 8 amperes each, what is the minimum amperage rating of the conductors feeding the phase converter? | nec_codebook |
In a 3-wire, three-phase AC system feeding a motor, with one conductor grounded, where must fuses for motor overload protection be inserted in the circuit? | nec_codebook |
What other protection is required on motor overload relays and other devices that are not capable of opening short circuits or ground faults? | nec_codebook |
When two disconnecting means are utilized, one for disconnecting the motor and motor controller from the circuit and the other for disconnecting the motor control circuit from its power supply, where must these two disconnects be located? | nec_codebook |
By definition, what is a motor controller? | nec_codebook |
Every motor controller must be capable of starting and stopping a motor. What else must it be capable of? | nec_codebook |
An autotransformer motor starter must be so designed that it has at least how many starting positions? | nec_codebook |
Other than the requirements stated in Question 9-38, what other design considerations are required of an autotransformer? | nec_codebook |
What is the speed at which motor-starter rheostats for DC motors operated from a constant voltage supply must interrupt the power supply before the motor falls to a certain level? | nec_codebook |
What is the minimum number of conductors a motor controller must open? | nec_codebook |
How many motors connected to a circuit in excess of 600 volts are allowed to be connected to each motor controller? | nec_codebook |
Where one side of the motor control circuit is grounded; the motor control circuit should be arranged so that what type of ground in the remote control device will not start the motor? | nec_codebook |
If the phase-to-neutral voltage in a three-phase system is 2400 volts, approximately how much is the phase-to-phase voltage? | nec_codebook |
How many disconnecting means are required for electric motors receiving electrical energy from more than one source? | nec_codebook |
What are the jobs required of motor-circuit overcurrent protection? | nec_codebook |
If the phase-to-neutral voltage in a three-phase system is 2400 volts, approximately how much is the phase-to-phase voltage? | nec_codebook |
When the frame of a stationary motor is not grounded and complies with NEC regulations, what provision must be made? | nec_codebook |
The frames of all portable motors over a certain voltage must be guarded or grounded. What is this voltage? | nec_codebook |
What is the minimum size disconnecting means allowed for a hermetic refrigerant motor-compressor? | nec_codebook |
Where must the disconnecting means for an air-conditioning or refrigerating apparatus be located? | nec_codebook |
Branch-circuit conductors supplying a single motor-compressor must have an ampacity not less than what percent of the motor-compressor rated-load current? | nec_codebook |
If each motor-compressor must be protected against overload and failure to start, which of the following means is acceptable? | nec_codebook |
According to NEC Section 440.52, which of the methods listed is an acceptable means of protecting motor-compressors against overloads and failures to start? | nec_codebook |
When is a room air conditioner considered to be a single motor unit in determining its branch-circuit requirements? | nec_codebook |
If a single motor-compressor has a nameplate rated-load current of 34.5 amperes, what should the current-carrying rating be for the branch-circuit conductors; rounded off to the closest whole number? | nec_codebook |
What is the minimum rating for a disconnecting means for the circuit in Question 9-56 when rounded off to the closest whole number? | nec_codebook |
If a replacement motor-compressor draws 38.7 amperes, what is the minimum rating for a disconnect means? | nec_codebook |
Which of the following are recognized types of phase converters? | nec_codebook |
If any connections or extensions lead into or terminate through a hazardous area above the floor, what is considered within that hazardous area? | nec_codebook |
What is the classification of buildings used for storing or servicing aircraft that use gasoline, jet fuels, or other volatile flammable liquids or gases? | nec_codebook |
What is considered a Class I, Division 2 hazardous location in a hangar? | nec_codebook |
What type of wiring must be used in a hazardous area as defined in Section 513.3 of the NEC? | nec_codebook |
What hazards does the NEC recognize in theaters, cinemas, and similar properties? | nec_codebook |
Under what article of the NEC do hospitals and other health-care facilities fall? | nec_codebook |
If the phase-to-neutral voltage in a three-phase system is 2400 volts, approximately how much is the phase-to-phase voltage? | nec_codebook |
If the disconnecting means for a 120/240-volt circuit for a gasoline dispenser must disconnect all conductors, what must it include? | nec_codebook |
What trade size must conduit to a splice box be sealed if it is 2 inches or larger in Class I, Division 1 locations? | nec_codebook |
What percentage of the ignition temperature of the gas or vapor involved in its operation should the external surface of totally enclosed motors of Types (2) or (3) never exceed? | nec_codebook |
In a Class I location, where a pendant fixture with a rigid stem longer than 12 inches must be braced, how far should it be braced from the lower end of the fixture? | nec_codebook |
In a dust-ignitionproof enclosure supplied by a horizontal raceway, how long does the conduit length need to be in order to not require a raceway seal? | nec_codebook |