NATE Exam: Core Essentials

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d (very important)

The ability to utilize all types of communication skills is ____ to the HVACR technician.

a. not as important as "hands-on" technical skills
b. somewhat important
c. unimportant
d. very important

d (all of the above: clear, complete, concise)

It is important to be ____ in filling out service orders so that office staff, other technicians, and customers will know what work you completed on the job.

a. clear
b. complete
c. concise
d. all of the above

d (Refrigerant)

When explaining to a customer that you have adjusted the system charge, which of the following terms is most appropriate?

a. Freon
b. Gas
c. Juice
d. Refrigerant

a (can help you diagnose the problem)

Listening carefully to what a customer is telling you ____.

a. can help you diagnose the problem
b. is a waste of time
c. is not necessary
d. often will only confuse you

b (listen to the customer first, then ask questions)

When you arrive at a service call and meet the customer, you should ____.

a. ask questions first, then listen to what the customer has to say
b. listen to the customer first, then ask questions
c. avoid discussion with the customer
d. remind the customer that you are the professional and get on with your work

b (1,600 ft3)

What is the volume of a room that measures 10 ft by 20 ft with an 8-ft ceiling?

a. 800 ft3
b. 1,600 ft3
c. 2,400 ft3
d. 3,200 ft3

b (1,200 CFM)

What is the CFM requirements for an 1,800-ft2 house with 8-ft ceilings, if five air changes per hour are needed?

a. 400 CFM
b. 1,200 CFM
c. 1,600 CFM
d. 2,400 CFM

c (1,600 CFM)

What is the CFM requirement for an 2,400-ft2 house with 8-ft ceilings, if five air changes per hour are needed?

a. 400 CFM
b. 1,200 CFM
c. 1,600 CFM
d. 2,400 CFM

a (79 in2)

What is the cross-sectional area of a 10-in round metal duct?

a. 79 in2
b. 200 in2
c. 314 in2
d. 418 in2

Note: Area of a circle = π x radius^2

d (1,800 ft/min)

How fast does air with a velocity pressure of 0.20 in. w.g. move through a round duct?

a. 400 ft/min
b. 1,200 ft/min
c. 1,600 ft/min
d. 1,800 ft/min

Note: Velocity = 4005 x (the square root of velocity pressure)

d (1,800 ft/min)

How fast does air with a velocity pressure of 0.20 in w.g. move through a square duct?

a. 400 ft/min
b. 1,200 ft/min
c. 1,600 ft/min
d. 1,800 ft/min

Note: Velocity = 4005 x (the square root of velocity pressure)

d (all of the above: honest, loyal, patient)

Customers depend on you to be ____.

a. honest
b. loyal
c. patient
d. all of the above

c (demonstrate system operation and describe basic maintenance procedures to the customer)

Before leaving a service call, you should be sure to ____.

a. ask the customer for referrals
b. collect payment in cash if possible
c. demonstrate system operation and describe basic maintenance procedures to the customer
d. try to sell the customer an equipment upgrade

d (All of the above: it can cut hard or soft drawn copper; it leaves no metal shavings to contaminate the system; it produces a clean, square cut.)

What is the advantage of using a tube cutter to cut copper pipe?

a. It can cut hard or soft drawn copper
b. It leaves no metal shavings to contaminate the system
c. It produces a clean, square cut
d. All of the above

a (soft drawn copper)

Spring-type benders may be used on ____.

a. soft drawn copper
b. hard drawn copper
c. all copper pipe
d. steel pipe

a (make a mechanical joint in tubing)

A flaring tool is used to ____.

a. make a mechanical joint in tubing
b. measure pipe diameters
c. remove burrs from piping
d. solder tubing without the use of coupling

d (solder tubing without the use of couplings)

A swaging tool is used to ____.

a. cut copper tubing
b. make a mechanical joint in tubing
c. remove burrs from piping
d. solder tubing without the use of couplings

a (It is very accurate)

What is one of the advantages of a glass-stem thermometer?

a. It is very accurate
b. It is very durable
c. It comes with a digital readout
d. Non of the above

b (dry-bulb)

In discussing human comfort, the temperature most commonly referred to is ____.

a. dew point
b. dry-bulb
c. wet-bulb
d. Fahrenheit

d (wet-bulb)

A sling psychrometer uses two glass-stem thermometers. One measures dry-bulb, and the other measures ____.

a. dew point
b. enthalpy
c. relative humidity
d. wet-bulb

b (Bourdon tube)

A standard refrigeration manifold uses what type of element to measure pressure?

a. Bellows
b. Bourdon tube
c. Diaphragm
d. Spring

c (30 in. Hg to 350 psig)

What is the pressure range of a standard compound gauge on a refrigerant manifold?

a. 0 to 350 psig
b. 0 to 500 psig
c. 30 in. Hg to 350 psig
d. 30 in. Hg to 500 psig

d (Vacuum pump)

What is the best tool for removing moisture and non-condensibles from a system before adding refrigerant?

a. Manifold gauge
b. Micron analyzer
c. Recovery machine
d. Vacuum pump

b (microns)

A vacuum gauge reads pressure in ____.

a. inches of mercury
b. microns
c. psia
d. psig

c (Micronic)

Which of the following is not a method of leak detection?

a. Soap bubbles
b. Electronic
c. Micronic
d. Ultrasonic

a (Recovery machine)

To prevent the release of refrigerant to the atmosphere while removing it from a system, what type of equipment must be used?

a. Recovery machine
b. Recycling machine
c. Reclaim machine
d. Vacuum pump

b (air velocity)

An anemometer uses a small fan blade to measure ____.

a. air pressure
b. air velocity
c. air volume
d. static pressure

c (No flux is required)

What is one of the advantages of using silver brazing rods for copper-to-copper joints?

a. A lower melting temperature is required
b. A propane torch is normally used
c. No flux is required
d. No nitrogen purge is needed

d (all of the above)

"Housekeeping" includes ____.

a. disposal of waste
b. fire prevention and protection
c. proper storage of materials
d. all of the above

b (Goggles)

What type of eye protection should you wear when drilling overhead?

a. Face shield
b. Goggles
c. Side shields
d. Spectacles

b (DOT)

What agency regulates cylinders and chemicals transported in a service vehicle?

a. ASHRAE
b. DOT
c. EPA
d. OSHA

a (contain information about personal protective equipment)

Material safety data sheets ____.

a. contain information about personal protective equipment
b. do not provide recommendations regarding emergency procedures
c. should be kept in a safe place off-site
d. should be read after any chemical products have been used

d (Never)

When should oxygen be used in a refrigeration system?

a. To clear a restriction in the line
b. To pressurize for leak-testing
c. To purge lines for brazing
d. Never

c (Class A is an "ordinary" fire that involves the burning of wood, paper, or textile products, extinguishing agent: water. Class B is a fire that contains oil, grease, paint, varnish, or other chemicals, extinguishing agent: foam. Class C is an electrical fire, extinguishing agent: carbon dioxide.)

Which of the following classifications of fire extinguishers should be used for electrical fires?

a. A
b. B
c. C
d. D

d (All of the above: asphyxiating, flammable, toxic)

Which of the following categories could be considered a hazardous atmosphere in a confined space?

a. Asphyxiating
b. Flammable
c. Toxic
d. All of the above

a (Low oxygen level)

Which of the following best describes an asphyxiating atmosphere?

a. Low oxygen level
b. Presence of ammonia
c. Presence of carbon monoxide
d. Presence of nitrogen

c (5 ft)

If a ladder is placed against a wall that is 20 ft tall, what is the proper distance away from the wall for the base of the ladder?

a. 3 ft
b. 4 ft
c. 5 ft
d. 6 ft

c (maintain three points of contact)

When using a ladder, you should always ____.

a. extend the ladder 18 in. above the roof line
b. face away from the ladder
c. maintain three points of contact
d. straddle the space between the ladder and a nearby object

a (Disconnect and lock out power before starting unless testing requires the power to be on)

What is one of the most important safety precautions that you can take when working on electrical equipment?

a. Disconnect and lock out power before starting unless testing requires the power to be on
b. Keep one hand in your pocket while working on the power circuit
c. Label all hot wires before starting
d. Wear gloves suitable for high voltages

a (When current travels through a ground path other than the neutral)

When does a ground fault circuit interrupter open an electric circuit?

a. When current travels through a ground path other than the neutral
b. When the circuit is overloaded
c. When there is a short circuit
d. All of the above

b (only by the person who installed the locks)

Proper lockout/tagout procedures state that locks placed on a lockout device may be removed ____.

a. by anyone on the job site
b. only by the person who installed the locks
c. only after all fuses have been replaced
d. only when the equipment is grounded

c (evaporation)

A natural cooling process produced by moisture on the skin changing to low-pressure steam is called ____.

a. conduction
b. convection
c. evaporation
d. radiation

a (adding moisture)

During the heating season, human comfort can be enhanced without changing the temperature of the air by ____.

a. adding moisture
b. reducing moisture
c. increasing air filtration
d. increasing air speed

a (completely closed)

During the cooling season, dampers on bypass humidifiers should be ____.

a. completely closed
b. completely open
c. set at 25%
d. set at 50%

d (all of the above: liquid, solid, gas)

All matter can exist as a ____.

a. liquid
b. solid
c. gas
d. all of the above

c (potential)

Stored energy is called ____ energy.

a. controlled
b. kinetic
c. potential
d. quantum

c (sensible)

Heat that you can feel and measure directly with a thermometer is called ____ heat.

a. absolute
b. latent
c. sensible
d. super

b (latent)

The heat energy change associated with a phase (state) change is called ____ heat.

a. absolute
b. latent
c. sensible
d. super

d (specific)

The amount of heat (Btu) needed to raise the temperate of 1 lb of a substance 1°F is called the ____ heat of the substance.

a. absolute
b. latent
c. sensible
d. specific

b (liquid, solid)

The latent heat of fusion is the amount of energy required to change 1 lb of a substance from the ____ phase to the ____ phase without changing its temperature.

a. liquid, vapor
b. liquid, solid
c. solid, vapor
d. vapor, liquid

c (144 Btu)

At 32°F, 1 lb of ice can be changed to 1 lb of water by adding ____ Btu.

a. 32 Btu
b. 44 Btu
c. 144 Btu
d. 970 Btu

d (970 Btu)

At 212°F, 1 lb of water can be changed to 1 lb of steam by adding ____ Btu.

a. 32 Btu
b. 44 Btu
c. 144 Btu
d. 970 Btu

a (saturated)

When liquid and vapor phases of a substance exist together, and no more liquid can vaporize without more energy being added, the vapor is said to be ____.

a. saturated
b. stabilized
c. subcooled
d. superheated

d (superheat)

When a vapor is heated to a temperature higher than its saturation point, both the added heat and the temperature above saturation are called ____.

a. latent heat
b. sensible heat
c. specific heat
d. superheat

b (evaporation)

The process of molecules escaping from the surface of a liquid is called ____.

a. condensation
b. evaporation
c. saturation
d. subcooling

c (sublimation)

The process of a solid turning directly into a vapor without going through the liquid state is called ____.

a. saturation
b. subcooling
c. sublimation
d. superheating

b (kinetic)

The continuous movement of molecules within a liquid or gas is called ____ energy.

a. atomic
b. kinetic
c. potential
d. stored

a (latent, sensible)

Enthalpy includes both ____ and ____ heat energy.

a. latent, sensible
b. latent, specific
c. sensible, specific
d. specific, absolute

d (weight)

The measurement of the force that gravity exerts is called ____.

a. mass
b. specific matter
c. volume
d. weight

b (mass)

The amount of matter in a substance is called ____.

a. gravity
b. mass
c. volume
d. weight

a (density)

Weight per unit volume or mass per unit of volume is called ____.

a. density
b. specific gravity
c. specific mass
d. specific volume

d (specific volume)

Volume per unit of mass or weight is called ____.

a. density
b. specific gravity
c. specific mass
d. specific volume

c (0.075 lb/ft3)

Under standard conditions, air weighs approximately ____ lb/ft3.

a. 0.055 lb/ft3
b. 0.065 lb/ft3
c. 0.075 lb/ft3
d. 0.085 lb/ft3

d (86°)

Solve to find the Fahrenheit temperature corresponding to 30°C.
a. 32°
b. 68°
c. 70°
d. 86°

Note: 32°F = 0°C. 9/5°F = 1°C.

°F = (9/5 x °C) + 32
°C = (°F - 32) x 5/9

b (68°)

Solve to find the Fahrenheit temperature corresponding to 20°C.
a. 32°
b. 68°
c. 70°
d. 86°

Note: 32°F = 0°C. 9/5°F = 1°C.

°F = (9/5 x °C) + 32
°C = (°F - 32) x 5/9

d (26.7°C)

Solve to find the Celsius temperature corresponding to 80°F.
a. -1.1°C
b. 0.0°C
c. 15.6°C
d. 26.7°C

Note: 32°F = 0°C. 9/5°F = 1°C.

°F = (9/5 x °C) + 32
°C = (°F - 32) x 5/9

c (15.6°C)

Solve to find the Celsius temperature corresponding to 60°F.
a. -1.1°C
b. 0.0°C
c. 15.6°C
d. 26.7°C

Note: 32°F = 0°C. 9/5°F = 1°C.

°F = (9/5 x °C) + 32
°C = (°F - 32) x 5/9

b (doubled)

If the absolute temperature of a gas is doubled, under constant pressure the volume will be ____.

a. cut in half
b. doubled
c. increased
d. unchanged

b (1.2 ft3)

What is the new volume of 1 ft3 of air at 0°F when heated to 100°F?

a. 1.0 ft3
b. 1.2 ft3
c. 2.0 ft3
d. 3.0 ft3

Note: Vf = Vi x (Tf / Ti)

T = °F + 460

c (44.7 psia)

If gauge pressure reads 30 psi, what is the corresponding absolute pressure?

a. 15.7 psia
b. 34.7 psia
c. 44.7 psia
d. 60.7 psia

c (Dalton's)

The law that applies to the total pressure exerted by a mixture of gases or vapors is called ____ Law.

a. Boyle's
b. Charles'
c. Dalton's
d. Newton's

d (6.28 x 10^18)

A coulomb is a charge of ____ electrons.

a. 6.28
b. 628
c. 628 Million
d. 6.28 x 10^18

b (electron flow)

An ampere is a measurement of ____.

a. electrical charge
b. electron flow
c. opposition to current
d. potential energy

b (force that moves electrons through a circuit)

Voltage is best described as the ____.

a. amount of power being used in a circuit
b. force that moves electrons through a circuit
c. magnetic field surrounding a conductor
d. resistance to the flow of electrons

b (resistance)

Current in a circuit is limited by ____.

a. heat
b. resistance
c. temperature
d. voltage

a (conductor)

A substance that permits the free movement of electrons is called a(n) ____.

a. conductor
b. insulator
c. resistor
d. semiconductor

c (A short, large-diameter conductor)

Which of the following conductors would have the least resistance?

a. A long, large-diameter conductor
b. A long, small-diameter conductor
c. A short, large-diameter conductor
d. A short, small-diameter conductor

c (double)

If the voltage in a circuit is doubled and the resistance remains the same, the current will ____.

a. drop to zero
b. be cut in half
c. double
d. stay the same

d (25 V)

What is the voltage of a circuit if the resistance is 5Ω and the current is 5 A?

a. 1 V
b. 2.5 V
c. 10 V
d. 25 V

a (2Ω)

A circuit has a voltage of 10 V and a current of 5 A. What is the resistance?

a. 2 Ω
b. 15 Ω
c. 20 Ω
d. 50 Ω

a (sum of all the resistances in the circuit)

The total resistance of a series circuit is equal to the ____.

a. sum of all the resistances in the circuit
b. first resistance only
c. last resistance only
d. average of all the resistances in the circuit

c (the sum of the currents through the individual paths)

The total current in a parallel circuit is ____.

a. measured and divided by the number of circuit paths
b. measured only at the first circuit path
c. the sum of the currents through the individual paths
d. the total of the first and last circuit paths

c (power)

The rate of doing work is called ____.

a. amperage
b. electricity
c. power
d. voltage

c (1,000 W)

One kilowatt is equal to ____.

a. 10 W
b. 100 W
c. 1,000 W
d. 10,000 W

d (All of the above)

Which of the following equations is used to solve for electric power?

a. P = E x I
b. P = I^2 x R
c. P = E^2 / R
d. All of the above

a (1 kW)

What is the power in a circuit that has a current of 10 A and a resistance of 10Ω?

a. 1 kW
b. 10 kW
c. 100 kW
d. Cannot be determined by the information given

c (the same as the voltage induced per turn of the primary coil)

The voltage induced in each turn of the secondary coil of a transformer is ____.

a. half the voltage induced per turn of the primary coil
b. twice the voltage induced per turn of the primary coil
c. the same as the voltage induced per turn of the primary coil
d. determined by the ratio of turns in the primary coil to runs in the secondary coil

c (volt-amperes)

The load rating of a transformer is stated in ____.

a. amperes
b. volts
c. volt-amperes
d. watts

d (stator, rotor)

An ac induction motor consists of a stationary part called the ____ and a rotating part called the ____.

a. field, armature
b. primary winding, secondary winding
c. start winding, run winding
d. stator, rotor

a (1,200 RPM)

What is the synchronous speed of a three-phase motor that has six poles and is operated on a 60-Hz alternating current?

a. 1,200 RPM
b. 3,600 RPM
c. 4,320 RPM
d. 7,200 RPM

a (The lower the power factor, the less efficient the motor is)

How does the power factor of an inductive motor affect efficiency?

a. The lower the power factor, the less efficient the motor is
b. The lower the power factor, the more efficient the motor is
c. The higher the power factor, the less efficient the motor is
d. The power factor has no effect on the efficiency of a motor

c (Shaded-pole)

Which of the following single-phase ac motors does not have a start winding?

a. Capacitor-start, capacitor-run
b. Permanent split-capacitor
c. Shaded-pole
d. Split-phase

c (75 to 80%)

A centrifugal switch opens the start winding circuit when a capacitor-start motor reaches approximately ____% of its full speed.

a. 50 %
b. 60 to 70%
c. 75 to 80%
d. 90 to 100%

d (start, run)

A run capacitor is always connected to the ____ and ____ terminals.

a. primary, secondary
b. run, common
c. start, common
d. start, run

c (start capacitor. Note: Terminal No. 1 on all potential relays is always connected to the start capacitor. Terminal No. 2 is always connected to the start winding terminal on the motor or compressor. Terminal No. 5 is always connected to the common terminal of the motor or compressor.)

Terminal No. 1 on all potential relays is always connected to the ____.

a. common terminal
b. run terminal
c. start capacitor
d. start terminal

c (2, 5)

The coil of a voltage relay is between terminal ____ and terminal ____ of the relay.

a. 1, 5
b. 1, 2
c. 2, 5
d. 3, 5

d (Three-phase)

What type of ac motor has the highest starting torque and the greatest efficiency?

a. Capacitor-start, capacitor-run
b. Permanent split-capacitor
c. Split-phase
d. Three-phase

c (9)

How many terminals does a dual-voltage three-phase motor have?

a. 3
b. 6
c. 9
d. 12

a (aid the technician in finding the problem)

The primary function of any wiring diagram is to ____.

a. aid the technician in finding the problem
b. help the owner repair the problem
c. provide the location of the components
d. reduce repair time

a (One)

How many functions is an individual circuit in a control system designed to control?

a. One
b. Two
c. Three
d. Unlimited

c (switch)

The five basic components common to all schematics are a power supply, a path, a load, a legend, and a ____.

a. contactor
b. relay
c. switch
d. thermostat

c (functions)

The intention of the overall schematic is to show how the circuit ____.

a. components are connected
b. fails
c. functions
d. looks

c (ladder)

The type of schematic that provides the most helpful troubleshooting information for the service technician is the ____ diagram.

a. connection
b. installation
c. ladder
d. pictorial

c (loads)

Devices that consume power and convert it to some other form of energy, such as motion or heat, are ____.

a. contacts
b. fuses
c. loads
d. transformers

d (transformer)

The normal dividing line for voltage changes in a schematic is the ____.

a. contactor
b. fuse
c. relay
d. transformer

d (legend)

The part of the schematic that lists and explains the system components is called the ____.

a. appendix
b. guide
c. index
d. legend

a (electrically operated)

Relays and contactors are ____ control switches.

a. electrically operated
b. manually operated
c. pressure-activated
d. temperature-activated

d (series)

A(n) ____ circuit allows the same current to flow through all of the components.

a. ac
b. dc
c. parallel
d. series

c (parallel)

A(n) ____ circuit has multiple paths for current flow.

a. ac
b. dc
c. parallel
d. series

d (Series-Parallel)

What types of circuits are primarily used in control and safety applications?

a. Continuous
b. Parallel
c. Series
d. Series-Parallel

b (in parallel with the circuit being tested)

When testing with a voltmeter, you should place the meter ____.

a. in series with the circuit being tested
b. in parallel with the circuit being tested
c. on the highest possible setting
d. on the lowest possible setting

d (There is a short circuit)

What does a resistance rating of 0Ω indicate?

a. The circuit is open
b. The meter needs a new battery
c. The meter needs to be recalibrated
d. There is a short circuit

c (isolated from all energy sources)

When you use an ohmmeter, the circuit being measured must be ____.

a. energized
b. in use
c. isolated from all energy sources
d. at least 1.5 V

a (0Ω)

When you test a switch with an ohmmeter, a reading of ____ indicates that the switch is closed.

a. 0 Ω
b. 24 V ac
c. 120 V ac
d. infinity

b (close to the middle of the range)

On all meters, digital and analog, the scale used should indicate the measurement ____.

a. close to the bottom of the range
b. close to the middle of the range
c. close to the top of the range
d. anywhere within the range

c (0 V ac)

When testing across a closed switch in an energized circuit, you should read ____.

a. 0 Ω
b. infinite resistance
c. 0 V ac
d. 120 V ac

b (make sure that the jaws are closed)

When using a standard clamp-on ammeter, you should ____ before taking a reading.

a. disconnect all of the wires in the circuit being tested
b. make sure that the jaws are closed
c. make sure that the jaws are open
d. shut down and lock out the equipment being tested

d (The start winding is open)

When testing compressor windings, you take the following readings:
C to R: 2 Ω
C to S: infinite resistance
R to S: infinite resistance
What is the diagnosis?

a. The compressor is good
b. The run winding is shorted
c. The start winding is shorted
d. The start winding is open

d (that have been removed from the circuit)

Capacitance meters must be used on capacitors ____.

a. connected in series
b. connected in parallel
c. in live circuits
d. that have been removed from the circuit

d (there is a short)

When testing a thermostat wire that has been removed from the circuit, you measure 0 Ω between red and white. This indicates that ____.

a. the transformer is bad
b. the wiring is good
c. there is high resistance in the wire
d. there is a short

a (in series with the circuit being tested)

When testing with an ammeter, you should place the meter ____.

a. in series with the circuit being tested
b. in parallel with the circuit being tested
c. on the highest possible setting
d. on the lowest possible setting

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