Prepare for the NCCER Electrical certification exam with these practice questions and answers. This guide covers electrical theory, NEC code, circuits, motors, and wiring methods.
Q: When is nonmetallic-steathed cable used
Answer: In a residential wiring system
Q: Phases of residential electrical wiring include
Answer: Rough in, Trim out, Testing and Troubleshooting
Q: What two groups are industrial electricians split into
Answer: Installers and maintenance personal
Q: How many hours of on job learning are required for an apprenticeship program each year
Answer: 2,000 hours
Q: AC Voltage Tag Colors Class 00
Answer: Beige tag 500 volts
Q: AC Voltage Tag Colors Class 0
Answer: Red tag 1,000 volts
Q: AC Voltage Tag Colors Class 1
Answer: White tag 7,500 volts
Q: AC Voltage Tag Colors Class 2
Answer: Yellow tag 17,000 volts
Q: AC Voltage Tag Colors Class 3
Answer: Green tag 26,500 volts
Q: AC Voltage Tag Colors Class 4
Answer: Orange tag 36,000 volts
Q: Replacing fuses is an important use of
Answer: A hot stick
Q: Asbestos banned in 1978, you need to assume any building constructed before 1980 has
Answer: Asbestos in it
Q: How many watts does one Horsepower have
Answer: 746 watts
Q: An electrical circuit at minimum contains a
Answer: Source, load, and switch
Q: Proton is the type of sub-atom particle with a
Answer: Positive charge
Q: EMF is another term used for
Answer: Voltage
Q: Electric charge is measured in
Answer: Coulombs
Q: I=E/R (current) = (voltage) / (resistance)
Answer: the current in a circuit equals the voltage difference divided by the resistance
Q: R=E/I (resistance) = (voltage) / (current)
Answer: The resistance of a circuit is equal to the voltage applied to the circuit divided by the current in a circuit
Q: E=IxR=IR (voltage)= (current)x(resistance)
Answer: The applied voltage to a circuit is equal to the product of the current and the resistance of the circuit
Q: The fourth band on a resistor represents
Answer: Tolerance
Q: Clamp-on amp meter is used to
Answer: Measure electrical current
Q: Current measured in amperes
Answer: Is the flow of electrons in a circuit
Q: One volt is the potential difference between two points for which one coulomb of electricity will do one _______ of work.
Answer: Joule
Q: Voltage is measured with a
Answer: voltmeter
Q: One volt applied across one ohm of resistance causes a current flow of one _______.
Answer: ampere
Q: Ewald is the force required to produce a current of one ampere through a resistance of
Answer: 1 ohm
Q: What do Coulombs measure?
Answer: electric charge
Q: Electrons is the driving force that makes current flow in a
Answer: Circuit
Q: Watts is the basic unit of measurement for
Answer: Electrical power
Q: The proton is the smallest particle of an element that will still retain the
Answer: Properties of that element
Q: The nucleus is the center of an
Answer: Atom
Q: What are protons and neutrons
Answer: Electrically positive and neutral particles
Q: What is an electron?
Answer: Negatively charged particle that orbits the nucleus of an atom
Q: Matter is any substance that has mass and
Answer: occupies space
Q: 1 kilowatt (kw) is the suffix for
Answer: 1,000 watts
Q: One megawatt (mw) is the suffix for
Answer: 1 million watts
Q: A battery source consist of two or more cells and
Answer: Convert chemical energy into electrical energy
Q: An electrical circuit is a complete path for
Answer: Current flow
Q: Ohm is the basic unit of measurement for
Answer: Resistance
Q: What is used to measure resistance
Answer: Ohm meter
Q: Ohms law is a statement of the relationship between
Answer: Current voltage and resistance in an electrical circuit
Q: Power is the rate of doing work or the rate at which energy is
Answer: Used or dissipated
Q: What is voltage drop
Answer: The change in voltage across a component
Q: A resistor is a component that normally
Answer: Opposes current flow in a DC circuit
Q: A schematic is a drawing in which
Answer: Symbols are used to represent the components in a system
Q: A Series circuit has only one route of
Answer: Current flow
Q: A relay is an electromechanical component used as a
Answer: Switching device
Q: What is a transformer
Answer: A device containing one or more coils of wire wrapped around a common core
Q: What is a solenoid?
Answer: And electromagnetic device such as a valve
Q: What is a joule?
Answer: a unit that measures work and energy.
Q: What do ammeters measure?
Answer: current
Q: A conductor has three or less
Answer: Valence electrons
Q: A pull box for a straight pull must be?
Answer: 8x the trade size of conduit
Q: A pull box for conduit entering at right angles must be
Answer: 6x the trade size of conduit
Q: What is NEC section 250?
Answer: Grounding
Q: A bus bar is not a type of?
Answer: Service disconnect
Q: Circuit breakers must be used if a grounded conductor is attached to the
Answer: Disconnect switch
Q: What is the most frequently used interior wire size
Answer: 12 awg
Q: If you have 4-6 12 awg wires in a conduit what would be the allowable current carrying capacity
Answer: 80%
Q: What is the minimum sized box they can be used in cubic inches if it was to contain 4 no.10 conductors and 2 no.12 conductors
Answer: 14 1/2 inch box
Q: A run of conduit must not have more than
Answer: 4 quarter bends between fittings and outlets (180 degrees)
Q: A fuse should be rated higher than the highest rated component in a?
Answer: Panelboard to be protected
Q: An open circuit occurs in a wiring system when?
Answer: A conductor is broken or separated
Q: What would ohms law be used to determine?
Answer: The voltage of a power supply
Q: Coulomb’s law states that?
Answer: Like-charged objects repel and opposite charged objects attract
Q: Ohm’s Law states?
Answer: Voltage= amps x resistance
Q: Direct current cannot change
Answer: Directions
Q: Alternating current changes directions at?
Answer: 60Hz
Q: Installation of a conductor will not affect the?
Answer: Resistance of a circuit
Q: In a series circuit the current has?
Answer: 1 path to take
Q: Maximum ampacity of an 8 awg is?
Answer: 50 amperes
Q: 15 amperes is the maximum standard over current device rating used to?
Answer: Protect instrument circuits in a panel board
Q: Interior of any dip tank can be considered as a?
Answer: Class 1, division 1 location
Q: Vertical run metal wire-ways surely supported at intervals not exceeding 15 feet of wire way and shall not have?
Answer: More than 1 joint between supports
Q: A continuous load is?
Answer: Load where the maximum current is expected to continue for three hours or more
Q: Underground ducts or conduits should be?
Answer: Sealed before entering buildings
Q: 87 1/2 is the minimum percentage rated voltage that a storage battery should?
Answer: Supply the emergency load
Q: Mostly grounding wires are identified as?
Answer: White or neutral gray
Q: Overcurrent protection must be placed on the secondary side of a transformer if?
Answer: A panel board is supplied by the transformer
Q: What is the minimum cover depth that a direct buried PVC cable must have?
Answer: 18 inches
Q: Direct buried cables that emerge from the ground must be protected up to?
Answer: 8 feet above the ground
Q: All conductors of a circuit must be installed in the same raceway to?
Answer: Minimize induction heating
Q: Service conductors buried under 18 inches or more should have?
Answer: A warning label placed in the trench
Q: Raceways cannot be used to?
Answer: Support other Raceways, cables, or cords
Q: What is the minimum vertical clearance that should be provided for service conductors from the height point of over which they pass?
Answer: 8 feet
Q: No more than six switches or circuit breakers should be?
Answer: On each service disconnection
Q: What is the color used to identify intrinsically safe conductors?
Answer: Blue
Q: A bonding jumper is required for equipment installed in ________ location?
Answer: Class I
Q: Motors in Class II, Division 1 locations must be?
Answer: totally enclosed pipe-ventilated
Q: Where are easily ignitable fibers/flying stored?
Answer: Class III division 2
Q: Aluminum should not be used as?
Answer: Grounding electrodes
Q: All 15/20-amp Receptacle outlets installed in bathroom of dwelling units should always?
Answer: Require ground fault circuit interceptor
Q: Megohmer (megger) Is used to?
Answer: Measure resistances is in a circuit
Q: Insulated or bare bus bars should be?
Answer: Mounted rigidly in panel boards
Q: Resistance affects the current flow in a?
Answer: Direct current electric current
Q: Enclosures installed in wet locations should be?
Answer: Weatherproof
Q: Emergency generators in case of normal power supply failure should be set to start in?
Answer: 15 minutes
Q: NEC considers high voltage at?
Answer: 1000 volts for alternating current and 120 to 1500 volts for direct current
Q: NEC considers low voltage at?
Answer: 50 to 1000 volts for alternating current and 120 to 1500 volts for direct current
Q: What are the single phase wire colors?
Answer: Black, red, blue, and white
Q: What are the three phase wire colors?
Answer: Brown, orange, yellow, and gray
Q: SF6 circuit breakers are used for?
Answer: Extra high voltage systems
Q: What is GIS?
Answer: Gas insulated switchgear
Q: The major function of the relay in a circuit breaker is to?
Answer: Activate the trip signal to open the Contacts
Q: Oil circuit breakers should not be used in?
Answer: High voltage power systems
Q: Delta transformers
Answer: Phase volt = line volt / phase amps x 1.732 = line amps
Q: WYE or Star transformers
Answer: Phase volts x 1.732 = line volts / phase amps = line amps
Q: Primary =
Answer: H1, H2, H3
Q: Secondary =
Answer: X1, X2, X3
Q: What is the main purpose of a transformer?
Answer: To change the output voltage
Q: What are the three parts of a basic transformer?
Answer: Primary winding, secondary winding, and core
Q: A magnetic field is generated around the coils when?
Answer: AC flows through a transformer coil
Q: When the fields from one coil cuts through the turns of a second coil what happens?
Answer: Voltage will be generated
Q: Mutual induction causes?
Answer: Voltage to be induced in a transformer
Q: What are the three basic types of iron core transformers?
Answer: Closed core, open core, and shell
Q: Stator windings can be best described as?
Answer: A structure of copper or aluminum wire coils
Q: What are the two most common 3 phase motor configurations?
Answer: Delta and Wye
Q: Some motor stators are designed to operate both ways, they are started as a WYE connected motor to help reduce starting current, then?
Answer: Changed to a Delta configuration for running
Q: What doubles in series and cut in half on the duel voltage connection?
Answer: Resistance
Q: Some three phase motors designed for operation over 600 volts may have more than?
Answer: 12 leads, motors with 15 – 18 leads are common in high-voltage insulations
Q: What is a type of DC motor field coil connected in parallel with the Armature?
Answer: Shunt motor
Q: Compound DC motor has one set of field coils that are?
Answer: Connected in parallel with the Armature and another set connected in series
Q: If a motor is controlled by a VFD and the motor just buzzes instead of turning it means?
Answer: The VFD frequency is set to low
Q: A pole equipped with both N.C and N.O contacts is designated as a?
Answer: Double throw pole
Q: Pick up voltage is the minimum allowable coil control voltage that will cause an?
Answer: Electromechanical device to energize
Q: Once energized the seal in voltage is the minimum allowable coil control voltage that?
Answer: Will keep the device energized
Q: The drop out voltage is defined as the coil voltage that is reached when the Armature return spring overpowers the magnetic field of the coil and?
Answer: The contacts of the device change position
Q: Relays and other devices have three published ratings what are they?
Answer: 1. Inrush current (make contact) capacity2. Normal or continuous (carrying) capacity3. Current break (opening) capacity
Q: Typical contact life of a relay range in between?
Answer: 100,000 and 500,000 operations
Q: The contact rating of a relay is based on?
Answer: The contacts for rated power
Q: DC diode protection circuit, a diode can be placed in parallel with the load so that it will?
Answer: Oppose any current flow when the load is energized by the relay contact
Q: RC protection circuit, the resistor/capacitor combination is selected so that?
Answer: The circuit is effectively resistive and it’s time constant is approximately equal to the time constant of the load
Q: Varistor protection circuit, the varistor is a solid-state device who’s resistance is?
Answer: Inversely proportional to the voltage applied across it
Q: Magnetic contactor, like relays control devices that?
Answer: Energize or deenergize loads by the use of a control signal
Q: How many poles do contactors typically have?
Answer: Between 1-6
Q: Contactors without overload protection maybe?
Answer: Used to control non-inductive loads
Q: Relay contacts that are defined being normally open (N.O) have?
Answer: Contacts that are open when the relay coil is energized
Q: Overload protection for motors is provided by?
Answer: An Overload relay which also protects the motor from overheating from too much current
Q: Magnetic controller uses an electro mechanical device to?
Answer: Open and close contacts
Q: Resistor controller is only used in?
Answer: DC motors
Q: Compensator controllers starts the motor at?
Answer: Reduced voltage through an auto transformer
Q: What are two types of compensator controllers?
Answer: Open and closed
Q: What are controllers classified as?
Answer: Either manual or magnetive
Q: What is the most common type of AC controller?
Answer: A cross line type
Q: Magnetic and thermal are the two types of?
Answer: Overload relays
Q: Seal in voltage is the minimum voltage needed to?
Answer: Keep a relay coil energized
Q: If the heater in a fixed IEC bi-metallic Overload relay fails?
Answer: The entire overload relay must be replaced
Q: A relay designated as a 3PDT-SB relay has?
Answer: N.O & 3 N.C contacts
Q: Motor controls are covered in?
Answer: NEC article 430. Part VII
Q: What does a Nema rated motor starter consist of?
Answer: One or more magnetic Contactors with associated overload relays assembled and wired in the same enclosure
Q: Class 40 is not?
Answer: A Nema rated class for the trip time of an overload relay
Q: NEC 430 part III covers?
Answer: Motor and controller circuit overload protection
Q: Class 1 locations are hazardous because?
Answer: Volatile flammable gases, vapors, or liquids are handled ( divisions 1 & 2 )
Q: Class 2 locations are hazardous because?
Answer: The presence of combustible dust
Q: Class 3 locations are hazardous because?
Answer: The presence of easily ignitable fibers or other flying material
Q: What is the most severe hazardous location?
Answer: Class 1, division 1
Q: “A Group”
Answer: Represents the most hazardous location
Q: Class one, division two is the classification and division of all?
Answer: Floor level areas up to a height of 18 ft in an airport hangar
Q: NEC article 504 covers?
Answer: Intrinsically safe equipment
Q: Integral drains will help prevent?
Answer: Moisture from collecting in raceway systems
Q: What is class one, division two?
Answer: An atmosphere that is normally hazardous
Q: What is the main purpose of an explosion proof flexible coupling?
Answer: To connect motors to a raceway
Q: Rigid metal conduit is approved for use in most?
Answer: Class one, division one locations
Q: In hazard locations were threaded metal conduit is required?
Answer: Joints must be made up with at least five threads fully engaged
Q: The NEC List three classifications of hazardous atmosphere’s?
Answer: There are two divisions for each classification
Q: There are four groups listed under?
Answer: Class one, division one
Q: Group C, F, and G are listed under?
Answer: Class two, division one
Q: Dust/ignition proof enclosure breakers must be used in?
Answer: Class two, division one hazardous locations
Q: In hazardous locations rigid metal conduit must?
Answer: Taper 3/4 per foot
Q: Seal fittings must be installed within 18 inches when?
Answer: Installing switches or other arc producing apparatus in class one, division one locations
Q: The purpose of padding fiber in a seal fitting is to?
Answer: Provide a dam to contain the sealing compound until it hardens
Q: EMT conduit is?
Answer: Too thin to be threaded
Q: RMC requirements can be found in
Answer: NEC article 344
Q: The voltage drop of conductors carrying alternating current in PVC will be?
Answer: Less than that of identical conductors in metal conduit
Q: What is use for a moisture seal?
Answer: The outer covering on liquid tight flexible metal conduit
Q: What is the maximum number of current carrying conductors allowed at any cross-section of a wire way without derating?
Answer: 30
Q: IMC is a type of conduit that?
Answer: Has a wall thickness less than that of RMC but thicker than EMT
Q: Installation specifications of surface metal raceways can be found in?
Answer: NEC 386
Q: Standoff support is used to?
Answer: Eliminate the need to offset the conduit where a fitting is
Q: Expansion couplings are used with?
Answer: PVC
Q: EMT and RMC have the same outside diameter in
Answer: Sixes 2 1/2″ & larger
Q: Aluminum conduit should not be?
Answer: Buried in soil or concrete containing calcium chloride
Q: What is the maximum spacing between horizontal wireway supports?
Answer: 10 feet
Q: Electrical Metallic Tubing (EMT) is?
Answer: The lightest duty and most widely used non-flexible metal conduit
Q: EMT and RMC connectors are not?
Answer: Interchangeable
Q: Because the wall thickness of IMC is less than that of rigid conduit it is?
Answer: Often referred to as a thin wall conduit
Q: RMC is made of?
Answer: Steel or aluminum
Q: Cellular ductways our designed to?
Answer: Extend conductors across a floor without embedding it into the floor
Q: A wood joist cannot be?
Answer: Drilled and less approved by the manufacture
Q: What are the types of conduit fittings?
Answer: LB, LL, LR, LRL, LBDN, LBD, SLB, C, T, TA, TB, GUAT, UB, X
Q: What are the types of conduit straps?
Answer: One hole, two hole, nail strap, CD, LCC
Q: A straight pull box should be?
Answer: Eight times the biggest conduit
Q: Myers hub is a?
Answer: Gasketed fitting used to provide a water tight conduit connection
Q: A 90° angle pull box should be?
Answer: Six times the biggest conduit
Q: SLB is the abbreviation for?
Answer: An entrance elbow
Q: What is a mogul?
Answer: A conduit body with a raised cover
Q: For an angle or U pull the length of a pullbox housing shielded conductors carrying over 600 V must be?
Answer: 36 times the outside diameter of the largest shielded conductor entering the box, the distance between entry and exit must be 36 times the diameter of the conductor as well
Q: Conduit offset multipliers at 10°
Answer: 5.8
Q: Conduit offset multipliers at 15°
Answer: 3.86
Q: Conduit offset multipliers at 22.5°
Answer: 2.6
Q: Conduit offset multipliers at 30°
Answer: 2
Q: Conduit offset multipliers at 45°
Answer: 1.41
Q: Conduit offset multipliers at 60°
Answer: 1.2
Q: What does a three point saddle consist of?
Answer: 3 bend degrees, 22.5, 45, 22.5/10, 20, 10/15, 30, 15/30, 60, 30 etc.
Q: What does a four point saddle consist of?
Answer: 4 bends, 2 offsets of the same size facing each other
Q: An acceptable method of identifying grounded conductors larger than NO. 6 AWG is by?
Answer: Tagging or making them white
Q: What is the diameter in inches of a conductor with a diameter of 40 mils?
Answer: 0.04
Q: 4/0 to 14 AWG is the most common conductors used for?
Answer: Light and power installations
Q: The normal location to provide overcurrent protection in an electrical current is?
Answer: Where the conductor receives its supply
Q: What is the recommended maximum voltage drop for conductors, feeders, and branch circuits combined
Answer: 5%
Q: Orange is the color reserved for?
Answer: Identifying the high leg of 3 phase, 4 wire system