NCC Practice Test 5

Conductors connected to the high leg of a four-wire delta system be color-coded with what color of insulation or tape?

Orange

A pocket knife can be used to deburr

PVC

Which of the following eliminates wrinkling or flattening when bending PVC?

Plug set

Which of the following protect the motor and control devices against overheating?

Solid-state overload relays

Which of the following is an NEC requirements for grounding and bonding cable tray installations?

Steel or aluminum trays may be used as equipment grounding conductors

A transformer can be checked for shorted turns using a

TTR tester

Which of the following describes circumference?

The distance around a circle

Which of the following occurs when the load applied causes the fibers on the tension side of the rung to stretch and permanently deform?

Transverse failure

What kind of mounting is often used in tunnels and other underground installations where equipment is separated by long distances?

Wall mounting

A triplen harmonics neutral current can be reduced by

adding harmonic filters at the load

Before starting a cable pull, make sure that

all communications equipment is in working order

A transformer that has the secondary winding connected in series with the primary at a junction terminal is an

autotransformer

Two 90 degree bends in the same piece of conduit are required for a

back to back bend

The most desirable method of exiting cable from a cable tray is

between rungs or from the end of the tray using a dropout plate

If the resonant frequency is near the harmonic voltage, the resultant harmonic current can

blow the capacitor fuses

The radius of a circle is defined as

the distance from the center point to the edge of the circle

In short vertical runs, the cables are usually supported by

the vertical riser elbow

Which of the following is a current transformer?

Oil-filled

A cable hanger elbow is used to

suspend cables in long vertical runs

The line voltages in a Y connection are

1.732 times higher than the phase voltages

Except for Type MC, all multiconductor cables operating at or above 600V must be separated by a solid divider from cables operating under

1000V

The resistance of switchgear should be checked using a

1000V megger

A buck-and-boost transformer has a primary current of 10A and the transformation ratio of 10:1. What is the secondary current?

100A

What is the standard output voltage of potential tranformers?

120V

An SSOLR initiates a trip if the phase currents exceed what percentage of the trip current dial setting?

125%

A typical hand-crank wire puller, using 30 pounds of force, can pull up to

1500 pounds

In a step-down transformer with a 4.16kV primary delta connection and 480/277V wye secondary, the transformer turns ratio is

15:1 (4160/277)

When performing thermographic surveys, a major deficiency is indicated by a gradient of

16* C

Given a cable tray that is available in the standard widths of 6, 12, 18, 24, and 36 inches, what is the minimum width of a 3 inch deep cable tray used for the following cables that are all 4/0 or larger: two with 1.5 inch diameter; three with 1.75 inch diameter; and two with 2.5 inch diameter?

18 inches

The contactor sequence for the circuit shown in the figure above is such that during the transition from reduced-voltage operation to full-voltage operation, the energized contactors are 2S and

1S

two junction boxes are each located on different walls, 12 inches from the same corner. Given a 90* bend with a take-up of 6 inches and a gain 2-1/4 inches, what is the developed length of the conduit between them?

21 3/4"

What is the voltage of the secondary in a transformer with 200 turns in the primary, 20 turns in the secondary, and an input voltage of 2,400V?

240V

Wires from a sensor to a ground fault relay should be no longer than

25'

What is the maximum length of cable weighing 5lbs/ft that can be pulled through a 45 degree bend with a coefficient of friction of 1.48 using equipment with a maximum pulling force of 2,000 pounds?

270

Which of the following types of transformers must be installed in a vault?

35kV oil-insulated transformers

When creating an offset using 10* bends, with a multiplier of 6, to cross a 6 inch obstruction, the distance between bends is

36 inches

The expected weight of an installed cable tray system is 300 pounds. Each support must be capable of carrying

375 pounds (125%)

Refer to the figure above. A multi-tap transformer has 1620 turns in the primary. There are 40 turns between each tap. Taps 3 and 6 are connected. Which taps must be connected to reduce output voltage by 5%?

5 and 4

The voltage imbalance trip point for a programmable solid-state overload relay is typically set for

5%

In general, the sidewall load on any raceway run should not exceed

500 pounds per foot of bend

Refer to the figure above. Which taps should be connected to increase the secondary voltage by 5%?

7 and 2

Which of the following can be used to bend IMC?

A hickey

Which of the following characteristics is an advantage for using an electromechanical relay versus a solid-state relay?

Ability to withstand surge currents

When does an off-delay relay provide the time delay?

After the relay is de-energized

Which of the following refers to the total load seen by the CT secondary?

Burden

Which symbol in the figure above represents a normally open, timed open contact of a timing relay?

C

Which of the following abbreviations is used on electrical drawings to represent an oscilloscope?

CRO

What components are installed to increase the power factor and decreases the cost of electricity caused by large inductive loads?

Capacitors

The formula pi x D is used to calculate

Circumference

Most NEMA-rated general purpose motors have an overcurrent trip class rating of

Class 20

Which of the following transformers is the most appropriate type of transformer to use for series street lighting?

Constant-current transformer

What type of transformer provides 120V between center-tapped terminal and each ungrounded terminal on either side and 240V across the full winding of each phase?

Delta-Delta

Which of the following types of transformers can be ventilated, air-cooled, or sealed?

Dry-type transformers

Which of the following should be used to cut EMT?

Hacksaw

Which of the following tests is conducted in order to detect loose connections?

Heat scanning test

Which of the following readings may indicate a problem when detecting neutral overloading in a receptacle branch circuit by measuring the neutral-to-ground voltage?

Higher than 2V

Which of the following forces are always present in an AC circuit?

Inductance and true power

When voltage is stepped down in a transformer, what happens to the current in the same circuit?

It is stepped up

Which of the following refers to the condition in which two circuits share the energy of one of the circuits?

Mutual induction

Capacitors are covered in

NEC Article 460

The installation of resistors and reactors is covered in

NEC Article 470

The three sections of switchgear enclosures are the front section, the bus section, and the

cable or termination section

To select a buck-and-boost transformer, use

charts provided by the manufacturer

A die used to

cut the threads in conduit

Field marking of service equipment shall include the

date fault current calculations performed

Welding cable may only be installed in a

dedicated cable tray

The insulating oil in a liquid filled transformer should be regularly tested for

dielectric strength

The method of supporting cable trays using threaded rods and hanger clamps is known as

direct rod suspension

Gain is best described as the

distance saved by the arc of 90* bend

Which of the following provides a curved surface for the cable to follow as it passes from the tray?

dropout plate

Most control transformers are

dry-type step-down

According to the NEC, neutral conductors size No. 6 and smaller must have a continuous marking of white or

gray

When installing single conductor cables in tray systems with conductors size 4/0 and larger, they must be

installed in a single layer

The voltages and currents used in the primary circuits of substations are reduced to usable levels by

instrument transformers

To ensure maximum safety in a control transformer, the secondary control circuit is

isolated from the primary line circuit

Nonstandard abbreviations on electrical prints will typically be defined on the

legend

Symbols used to show cable tray systems on working drawings are explained in the

legend

In a potential transformer, the voltage across the secondary terminals is always

lower than the primary voltage

An ampacity adjustment of conductors in cable tray is more likely to be required when installing

multiconductor cable

In a three-phase, four wire system, the conductor that is most likely to be affected by nonlinear loads is the

neutral

Circuit breaker ratings are given

on the breaker nameplate

A right triangle is any triangle with

one 90* angle

The preferred method for checking for damaged conduit before pulling cable is

performing a test pull

A downed power line is most likely to result in a

phase failure

Which of the following is most commonly used to cut RMC and IMC?

pipe cutter

A device that is used to step up generated voltage to make it suitable for commercial transmission is called a

power transformer

The basic purpose of switchgear is to

provide power system protection by automatically isolating faulty components

The continuous current that a circuit breaker can carry without exceeding a standard temperature rise is known as the

rated current

One of the advantages of an SSR over an EMR is its

response time

The most important consideration for selecting a current transformer for relaying is the

saturation characteristics

Which winding of a transformer is connected to the load?

secondary

Magnetic leakage in a transformer causes a decrease in ______ when the transformer is loaded.

secondary voltage

Connection diagrams should be used to

show the internal wiring connections between the parts that make up an apparatus

A residence with 120V and 240V loads is likely to be served by a

single phase transformer with two secondaries

The developed length of a bend is equal to the

sum of the horizontal and vertical distances minus the gain

When three solid-state relays are connected in series, the supply voltage must be

triple the minimum operating voltage for a single relay

Specialty step-down transformers are often

used for small work, such as doorbells and other signaling systems

The maximum 60Hz voltage that can be applied to a switch for one minute without causing insulation failure is known as the

withstand rating

A three phase, four wire system that has the advantage of providing three-phase power and allowing lighting to be connected between any of the secondary phases and the neutral would have a

wye secondary

The three basic methods of sensing ground faults are ground-return, residual, and

zero sequence