Journeyman Electrician (NEC) — All Questions

A box contains six 12 AWG conductors, one internal cable clamp and one duplex receptacle, all 12 AWG. What minimum box volume is required?

• a.20.25 cubic inches✓
• b.13.5 cubic inches
• c.18.0 cubic inches
• d.22.5 cubic inches

Count six conductors, one allowance for all internal clamps and two allowances for the device yoke, giving 9 volume allowances. Each 12 AWG allowance is 2.25 cubic inches, so 9 x 2.25 = 20.25 cubic inches. Counting only the conductors gives 13.5 cubic inches, and forgetting that a yoke counts as two conductors gives 18.0 cubic inches.2023 NEC §314.16(B)

A device box has three 14-2 NM cables with equipment grounding conductors entering through internal clamps, and one single-pole switch is installed. What minimum box volume is required?

• a.20.0 cubic inches✓
• b.18.0 cubic inches
• c.16.0 cubic inches
• d.22.5 cubic inches

Six insulated conductors count individually, all equipment grounding conductors together count as one, all internal clamps together count as one, and the switch yoke counts as two, for 10 allowances. At 2.00 cubic inches for 14 AWG, 10 x 2.00 = 20.0 cubic inches. The 18.0 answer misses one allowance, 16.0 omits both the clamp and grounding allowances, and 22.5 uses the 12 AWG allowance by mistake.2023 NEC §314.16(B)

What is the minimum trade size of EMT required for nine 12 AWG THHN conductors?

• a.One-half inch✓
• b.Three-quarter inch
• c.One inch
• d.One and one-quarter inch

Annex C, Table C1 shows that one-half inch EMT accepts nine 12 AWG THHN conductors, exactly meeting the requirement. Three-quarter inch EMT holds sixteen and one inch holds twenty-six, so both are larger than the minimum. Annex C may be used directly whenever all conductors are the same size and insulation type.2023 NEC Annex C, Table C1

When more than two conductors are installed in a raceway, what is the maximum permitted percentage of the raceway cross-sectional area they may occupy?

• a.53 percent
• b.31 percent
• c.40 percent✓
• d.60 percent

Chapter 9, Table 1 allows 53 percent fill for one conductor, 31 percent for exactly two conductors and 40 percent for three or more. The 60 percent value applies only to a nipple not exceeding 24 inches in length between boxes or enclosures.2023 NEC Chapter 9, Table 1

A short raceway nipple no longer than 24 inches connects two enclosures. What fill percentage is permitted?

• a.31 percent
• b.40 percent
• c.53 percent
• d.60 percent✓

Notes to Chapter 9, Table 1 permit a nipple not exceeding 24 inches in length to be filled to 60 percent of its total cross-sectional area, because heat buildup and pulling friction are both minimal over such a short run. The 40, 53 and 31 percent values are the normal fills for three or more, one, and two conductors respectively.2023 NEC Chapter 9, Table 1, Note 4

Four 3/0 AWG THWN conductors, each 0.2679 square inch in area, are pulled into rigid metal conduit. What is the minimum trade size?

• a.2 inch✓
• b.1 and 1/2 inch
• c.2 and 1/2 inch
• d.1 and 1/4 inch

Total conductor area is 4 x 0.2679 = 1.0716 square inches, and with more than two conductors only 40 percent of the raceway may be filled. One and one-half inch RMC allows only about 0.81 square inch at 40 percent, which is too little, while 2 inch RMC allows about 1.34 square inches and is adequate. Two and one-half inch is larger than the calculated minimum.2023 NEC Chapter 9, Table 4

What is the minimum cover for a direct-buried UF cable installed in a residential yard on a 120-volt, 20-ampere circuit that is NOT GFCI protected?

• a.18 inches
• b.24 inches✓
• c.12 inches
• d.6 inches

Direct-buried cables and conductors under all locations not otherwise covered require 24 inches of cover. The 12-inch reduction applies only to residential branch circuits rated 120 volts or less, 20 amperes or less, and provided with GFCI protection, so removing the GFCI removes the reduction. The 6-inch and 18-inch values belong to metal and nonmetallic raceways respectively.2023 NEC Table 300.5

What is the minimum burial cover for rigid metal conduit installed underground in a location not otherwise specified?

• a.18 inches
• b.12 inches
• c.6 inches✓
• d.24 inches

Rigid metal conduit and intermediate metal conduit are permitted at 6 inches of cover because the metal wall provides its own physical protection. Nonmetallic raceways listed for direct burial require 18 inches, direct-buried cable requires 24 inches, and 12 inches applies to GFCI-protected residential branch circuits.2023 NEC Table 300.5

What is the minimum burial cover for a nonmetallic raceway listed for direct burial without concrete encasement, installed under a lawn?

• a.18 inches✓
• b.6 inches
• c.24 inches
• d.12 inches

Listed nonmetallic raceways buried without concrete encasement require 18 inches of cover in locations not otherwise specified. Metal conduit needs only 6 inches, direct-buried cable needs 24 inches, and 12 inches applies to GFCI-protected 120-volt residential branch circuits.2023 NEC Table 300.5

A GFCI-protected 120-volt, 20-ampere residential branch circuit is direct buried in a yard. What is the minimum cover?

• a.18 inches
• b.6 inches
• c.12 inches✓
• d.24 inches

Residential branch circuits rated 120 volts or less and 20 amperes or less that have GFCI protection may be buried with only 12 inches of cover, because a ground fault from a dig-in will clear immediately. Without GFCI protection the general 24-inch requirement applies, and the 6- and 18-inch values belong to metal and nonmetallic raceways.2023 NEC Table 300.5

How must electrical metallic tubing be secured and supported on a normal horizontal run?

• a.Secured within 3 feet of each box and supported at least every 10 feet✓
• b.Secured within 12 inches of each box and supported every 4 and 1/2 feet
• c.Secured within 3 feet of each box and supported every 6 feet
• d.Support is required only every 10 feet with no requirement near boxes

EMT must be securely fastened within 3 feet of every box, cabinet or termination and supported at intervals not exceeding 10 feet. The 12-inch and 4 and 1/2-foot figures belong to Type NM and Type AC cable, and the 6-foot interval is the MC cable support spacing.2023 NEC §358.30(A)

How must Type NM cable be supported where it enters a box equipped with cable clamps?

• a.Secured within 8 inches of each outlet box or fitting and supported at intervals not exceeding 6 feet along the run
• b.Secured within 12 inches of the box and supported at least every 4 and 1/2 feet✓
• c.Secured within 3 feet of the box and supported every 10 feet
• d.Secured within 12 inches of each box and supported at intervals not exceeding 6 feet, matching the rule for Type MC cable

Type NM cable is secured within 12 inches of each box, cabinet or fitting and supported at intervals not exceeding 4 and 1/2 feet. The 8-inch figure applies to a single-gang nonmetallic box without clamps, the 3-foot and 10-foot values are EMT, and the 6-foot interval belongs to MC cable.2023 NEC §334.30

At what maximum interval must Type MC cable be supported and secured?

• a.Every 3 feet, and within 12 inches of every termination
• b.Every 4 and 1/2 feet, and within 12 inches of every termination
• c.Every 10 feet, and within 3 feet of every termination
• d.Every 6 feet, and within 12 inches of every termination✓

Type MC cable is secured at intervals not exceeding 6 feet and within 12 inches of every box, cabinet or fitting where the cable terminates. The 4 and 1/2-foot interval belongs to Types NM and AC, and the 10-foot interval belongs to EMT and other rigid raceways.2023 NEC §330.30

At what maximum interval must Type AC cable be supported?

• a.Every 6 feet
• b.Every 4 and 1/2 feet✓
• c.Every 10 feet
• d.Every 3 feet

Type AC armored cable is supported at intervals not exceeding 4 and 1/2 feet and secured within 12 inches of each termination. The 6-foot figure is for Type MC cable and 10 feet is for EMT, so mixing the cable types is the usual source of error here.2023 NEC §320.30

What is the maximum support spacing for a 1-inch trade size rigid PVC conduit?

• a.6 feet
• b.5 feet
• c.3 feet✓
• d.10 feet

PVC expands and sags with temperature, so support spacing depends on trade size: one-half through 1 inch is supported every 3 feet, 1 and 1/4 through 2 inch every 5 feet, and larger sizes at progressively longer intervals. The 10-foot spacing belongs to EMT and rigid metal conduit, which are far stiffer.2023 NEC §352.30(B)

What is the maximum total amount of bend permitted in one run of EMT between pull points?

• a.270 degrees
• b.180 degrees
• c.360 degrees✓
• d.540 degrees

No more than the equivalent of four quarter bends, or 360 degrees total, is permitted between pull points such as conduit bodies and boxes, because friction rises sharply with each bend. The same 360-degree limit appears in the articles for rigid metal conduit and PVC, so it is worth memorizing once.2023 NEC §358.26

A cable passes through a bored hole in a wood stud. If the edge of the hole is less than 1 and 1/4 inches from the nearest edge of the stud, what is required?

• a.The cable must be removed and rerouted through a notch cut into the edge of the wood stud rather than the bored hole
• b.A steel plate or bushing at least 1/16 inch thick installed to protect the cable✓
• c.A listed nonmetallic sleeve of any thickness
• d.Nothing additional is required, provided that the cable installed in the bored hole is Type MC or Type AC armored cable

When the required 1 and 1/4-inch setback cannot be maintained, a steel plate, sleeve or bushing at least 1/16 inch thick must cover the area of the wire so a drywall screw or nail cannot reach it. Notching is more damaging to the stud and creates the same exposure, and nonmetallic sleeves do not satisfy this rule.2023 NEC §300.4(A)(1)

A pull box is used for a straight pull, and the largest raceway entering it is 3 inch trade size. What is the minimum required length of the box in the direction of the pull?

• a.18 inches
• b.24 inches✓
• c.12 inches
• d.36 inches

For straight pulls, the box length must be at least eight times the trade size of the largest raceway: 8 x 3 = 24 inches. The 18-inch answer uses a factor of six, which applies to angle and U pulls, and 12 inches uses a factor of four that appears nowhere in the rule.2023 NEC §314.28(A)(1)

An angle pull box has one 2-inch raceway and one 1-inch raceway entering the same wall, with conductors turning 90 degrees. What is the minimum distance from that wall to the opposite wall?

• a.24 inches
• b.12 inches
• c.16 inches
• d.13 inches✓

For angle pulls the distance is six times the trade size of the largest raceway plus the sum of the diameters of the other raceways on the same wall: (6 x 2) + 1 = 13 inches. The 12-inch answer forgets to add the additional raceway, and 24 inches applies the straight-pull factor of eight.2023 NEC §314.28(A)(2)

How must liquidtight flexible metal conduit be secured on a normal run?

• a.Within 12 inches of each box and at intervals not exceeding 6 feet
• b.Within 3 feet of each box and at intervals not exceeding 10 feet
• c.Within 12 inches of each box or fitting and at intervals not exceeding 4 and 1/2 feet✓
• d.Support is not required for lengths of 6 feet or less in any application

LFMC is secured within 12 inches of each box, cabinet or fitting and supported at intervals not exceeding 4 and 1/2 feet. Certain short lengths used for flexibility or for connections to luminaires are exempt, but that exemption is narrow and does not apply to ordinary runs, and the 10-foot spacing belongs to rigid raceways.2023 NEC §350.30(A)

How many 12 AWG conductors may be installed in a 4-11/16 inch by 2-1/8 inch square box with a volume of 42.0 cubic inches, assuming no clamps, devices or fittings?

• a.21
• b.20
• c.16
• d.18✓

Each 12 AWG conductor requires 2.25 cubic inches, so 42.0 / 2.25 = 18.67, and the count must be rounded down to 18 whole conductors. The 21-conductor answer uses the 14 AWG allowance of 2.00 cubic inches, and 20 comes from rounding up rather than down.2023 NEC §314.16(A)

Direct-buried conductors emerging from grade must be protected by an approved enclosure or raceway from below grade to what height?

• a.8 feet above finished grade✓
• b.6 feet above finished grade
• c.10 feet above finished grade
• d.4 feet above finished grade

Protection must extend from below grade to at least 8 feet above finished grade, and the underground portion must reach at least 18 inches below grade. Six feet leaves the conductors within easy reach of damage, and neither 4 nor 10 feet is the code value.2023 NEC §300.5(D)(1)

What is the maximum fill percentage when exactly two conductors are installed in a raceway?

• a.40 percent
• b.31 percent✓
• c.53 percent
• d.60 percent

Two conductors are limited to 31 percent fill, a lower figure than the 40 percent allowed for three or more, because two round conductors of similar size can jam in a bend and damage insulation during the pull. One conductor may fill 53 percent, and 60 percent applies only to a nipple 24 inches or shorter.2023 NEC Chapter 9, Table 1

What is the minimum trade size of EMT required for twenty-four 12 AWG THHN conductors?

• a.One inch✓
• b.Three-quarter inch
• c.One and one-quarter inch
• d.One and one-half inch

Annex C, Table C1 shows one inch EMT accepts twenty-six 12 AWG THHN conductors, so twenty-four fit. Three-quarter inch holds only sixteen and is too small, while one and one-quarter inch holds far more than needed. Remember that twenty-four current-carrying conductors would also trigger a 45 percent ampacity adjustment.2023 NEC Annex C, Table C1

Conductors installed in an underground raceway in a wet location must have which characteristic?

• a.A nylon jacket, which by itself qualifies the conductor for wet locations
• b.Any thermoplastic insulation, since the raceway keeps water out
• c.Insulation rated 90 degrees C, regardless of wet-location listing
• d.Insulation listed for use in wet locations, such as THWN or THWN-2✓

Raceways in underground and other wet locations are considered wet inside, so the conductors must carry a wet-location listing such as THWN, THWN-2 or XHHW. The W in the type designation is what matters; plain THHN without the dual THWN-2 marking is a dry- and damp-location conductor, and a temperature rating or nylon jacket alone does not confer a wet-location listing.2023 NEC §310.10(C)

A junction box contains four 14 AWG conductors and two 12 AWG conductors, with no devices, clamps or fittings. What minimum box volume is required?

• a.12.5 cubic inches✓
• b.13.5 cubic inches
• c.11.0 cubic inches
• d.15.0 cubic inches

Each conductor is counted at the volume allowance for its own size: four 14 AWG at 2.00 cubic inches is 8.0, and two 12 AWG at 2.25 cubic inches is 4.5, for a total of 12.5 cubic inches. Using 2.25 for every conductor gives the incorrect 13.5 figure.2023 NEC §314.16(B)(1)

What is the minimum distance a 125-volt, 15- or 20-ampere receptacle must be located from the inside wall of a permanently installed pool?

• a.10 feet
• b.6 feet✓
• c.5 feet
• d.3 feet

General-use receptacles must be at least 6 feet from the inside walls of a permanently installed pool, measured along the shortest path a cord would follow. At least one required receptacle must also be located between 6 and 20 feet from the pool, and receptacles serving pool equipment must be GFCI protected.2023 NEC §680.22(A)(1)

A location is classified as Class I, Division 1 when which condition exists?

• a.Combustible dust in ignitible concentrations is present in the surrounding air only during infrequent abnormal operating conditions
• b.Easily ignitible fibers or flyings are handled or stored but are not normally likely to become suspended in the air
• c.Ignitible concentrations of flammable gases or vapors can exist under normal operating conditions✓
• d.Flammable liquids are stored only in sealed containers

Class I covers flammable gases and vapors, and Division 1 means ignitible concentrations can exist under normal operating conditions or frequently because of repair, maintenance or leakage. Combustible dust is Class II and ignitible fibers are Class III, so those descriptions point to different classifications.2023 NEC §500.5(B)(1)

A 15-ampere, 125-volt receptacle is installed outdoors in a wet location. What type of cover is required?

• a.Any weatherproof cover, effective only when the receptacle is unused
• b.A standard thermoplastic wall plate
• c.A cover that is weatherproof only when no plug is inserted
• d.A cover that is weatherproof whether or not an attachment plug is inserted✓

Receptacles in wet locations must have an enclosure that is weatherproof whether or not an attachment plug is inserted, commonly an in-use or bubble cover, because cords are often left plugged in outdoors. A cover that seals only when empty meets the lesser damp-location standard, not the wet-location rule.2023 NEC §406.9(B)(1)

In a dwelling unit, 125-volt and 250-volt, 15- and 20-ampere receptacles must generally be what type?

• a.Isolated-ground type
• b.Listed tamper-resistant type✓
• c.Hospital-grade type
• d.Twist-lock type

To prevent children from inserting objects into energized slots, these receptacles in dwelling units must be listed tamper-resistant. Hospital-grade and isolated-ground receptacles address other concerns and are not the general dwelling requirement.2023 NEC §406.12

Type NM (nonmetallic-sheathed) cable is NOT permitted in which of the following?

• a.Wet or damp locations✓
• b.The framed walls of a one-family dwelling
• c.An exposed dry run in the basement of a dwelling
• d.A concealed dry run in an attic

Type NM cable is prohibited in wet or damp locations because its sheath is not rated for moisture, and it may not be embedded in concrete or used where exposed to corrosive fumes. It remains a standard method for the dry, concealed and exposed interior wiring of dwellings.2023 NEC §334.12(B)

Flexible metal conduit (FMC) may serve as an equipment grounding conductor only where the total length in the ground-return path does not exceed 6 feet and which additional condition is met?

• a.The conduit is at least 1 inch trade size
• b.The circuit voltage does not exceed 50 volts
• c.The circuit conductors are protected at 20 amperes or less and the fittings are listed for grounding✓
• d.A separate equipment bonding jumper is installed on the outside of the conduit for its full length and terminated at both ends

FMC qualifies as an equipment grounding conductor only when the ground-return length is 6 feet or less, the overcurrent protection is 20 amperes or less, and the fittings are listed for grounding. Where any of these limits is exceeded, a separate equipment grounding conductor must be installed.2023 NEC §250.118(6)

The equipotential bonding grid required around a permanently installed pool must be formed with which conductor?

• a.6 AWG stranded aluminum
• b.8 AWG solid copper✓
• c.10 AWG solid copper
• d.4 AWG insulated copper

The equipotential bonding required around a pool uses a solid copper conductor not smaller than 8 AWG to tie together the reinforcing steel, coping, deck, ladders and equipment so that everyone stands at the same potential. Aluminum is not permitted for this bond, and 10 AWG is undersized.2023 NEC §680.26(B)

A box or conduit body installed in a wet location must meet which requirement?

• a.It may be any standard indoor box, provided that a weatherproof gasket is added between the box and the cover plate
• b.It must be completely filled with an approved duct seal compound to keep out all moisture and condensation
• c.It must be nonmetallic only
• d.It must be listed for wet locations and be installed so water cannot enter or accumulate within it✓

Boxes and fittings in damp or wet locations must be placed or equipped so water cannot enter or accumulate inside, and in wet locations they must be listed for that use. Both metallic and nonmetallic boxes are permitted if properly listed and installed, so material alone does not satisfy the rule.2023 NEC §314.15

A box contains six 14 AWG conductors, one internal cable clamp and one duplex receptacle wired with 14 AWG. What minimum box volume is required?

• a.16.0 cubic inches
• b.12.0 cubic inches
• c.20.25 cubic inches
• d.18.0 cubic inches✓

Count six conductors, one allowance for all internal clamps, and two allowances for the device yoke = 9 allowances. Each 14 AWG allowance is 2.00 cubic inches: 9 x 2.00 = 18.0. See NEC 314.16(B).

A device box has two 12-2 nonmetallic-sheathed cables with equipment grounding conductors entering through internal clamps, and one single-pole switch (12 AWG). What minimum box volume is required?

• a.18.0 cubic inches✓
• b.16.0 cubic inches
• c.20.25 cubic inches
• d.15.75 cubic inches

Four insulated 12 AWG conductors, all grounding conductors as one, all clamps as one, and the switch yoke as two = 8 allowances. At 2.25 cubic inches each: 8 x 2.25 = 18.0. See NEC 314.16(B).

How many 12 AWG conductors may be installed in a 22.5-cubic-inch box with no clamps, devices or fittings?

• a.9
• b.10✓
• c.12
• d.11

Each 12 AWG conductor requires 2.25 cubic inches: 22.5 / 2.25 = 10 conductors exactly. See NEC 314.16(A) and (B).

How many 14 AWG conductors may be installed in an 18.0-cubic-inch box with no clamps, devices or fittings?

• a.12
• b.10
• c.8
• d.9✓

Each 14 AWG conductor requires 2.00 cubic inches: 18.0 / 2.00 = 9 conductors. See NEC 314.16(A) and (B).

What is the minimum trade size of EMT required for sixteen 12 AWG THHN conductors?

• a.One-half inch
• b.One inch
• c.Three-quarter inch✓
• d.One and one-quarter inch

Annex C, Table C1 shows one-half-inch EMT holds nine 12 AWG THHN and three-quarter-inch EMT holds sixteen, so three-quarter inch is the minimum. See NEC Annex C, Table C1.

When exactly one conductor is installed in a conduit or tubing, what is the maximum permitted fill percentage?

• a.40 percent
• b.31 percent
• c.53 percent✓
• d.60 percent

Chapter 9, Table 1 permits 53 percent fill for a single conductor, 31 percent for two, and 40 percent for three or more. See NEC Chapter 9, Table 1.

Four 250 kcmil THWN conductors, each 0.3970 square inch, are pulled into EMT. What is the minimum trade size?

• a.3 inch
• b.1 and 1/2 inch
• c.2 inch
• d.2 and 1/2 inch✓

Total area = 4 x 0.3970 = 1.588 square inches at 40 percent fill. Two-inch EMT allows about 1.342 square inches and fails; 2 and 1/2-inch EMT allows about 2.343 square inches and works. See NEC Chapter 9, Tables 1 and 4.

What is the maximum support spacing for a horizontal run of 1/2-inch trade size rigid metal conduit?

• a.10 feet✓
• b.6 feet
• c.5 feet
• d.12 feet

Rigid metal conduit of 1/2 and 3/4 inch is supported at intervals not exceeding 10 feet, and it must be secured within 3 feet of each termination. See NEC 344.30(B)(2).

What is the maximum support spacing for a 2-inch trade size rigid PVC conduit?

• a.6 feet
• b.3 feet
• c.5 feet✓
• d.8 feet

PVC support spacing depends on trade size: 1/2 through 1 inch every 3 feet, and 1 and 1/4 through 2 inch every 5 feet. See NEC 352.30(B).

A cable is run through a notch cut in the edge of a wood stud. What is required to protect it?

• a.A plastic bushing of any thickness
• b.A steel plate at least 1/8 inch thick
• c.A steel plate at least 1/16 inch thick installed across the notch✓
• d.No protection if the cable is stapled at the notch

Where a cable is laid in a notch, a steel plate, sleeve or clip at least 1/16 inch thick must protect it from screws and nails. See NEC 300.4(A)(2).

A pull box is used for a straight pull, and the largest raceway entering it is 4-inch trade size. What is the minimum length of the box in the direction of the pull?

• a.16 inches
• b.24 inches
• c.32 inches✓
• d.48 inches

For straight pulls the box length must be at least eight times the trade size of the largest raceway: 8 x 4 = 32 inches. See NEC 314.28(A)(1).

An angle pull box has a 3-inch raceway and a 2-inch raceway entering the same wall with conductors turning 90 degrees. What is the minimum distance from that wall to the opposite wall?

• a.13 inches
• b.20 inches✓
• c.24 inches
• d.18 inches

For angle pulls the distance is six times the largest raceway plus the sum of the other raceway diameters on the same wall: (6 x 3) + 2 = 20 inches. See NEC 314.28(A)(2).

How must flexible metal conduit (FMC) be secured on a normal run?

• a.Within 12 inches of each box or fitting and at intervals not exceeding 4 and 1/2 feet✓
• b.Within 3 feet of each box and at intervals not exceeding 10 feet
• c.Within 12 inches of each box and at intervals not exceeding 6 feet
• d.Support is never required for FMC

FMC is secured within 12 inches of each box, cabinet or fitting and supported at intervals not exceeding 4 and 1/2 feet, with limited exceptions for flexibility. See NEC 348.30(A).

What is the minimum burial cover for any wiring method installed directly beneath a public street, road or driveway?

• a.12 inches
• b.6 inches
• c.18 inches
• d.24 inches✓

Under streets, highways, roads, alleys, driveways and parking lots, all listed wiring methods require 24 inches of cover. See NEC Table 300.5(A).

What is the smallest conductor size generally permitted for building branch-circuit wiring?

• a.18 AWG copper
• b.14 AWG copper✓
• c.16 AWG copper
• d.12 AWG copper

For general branch-circuit and building wiring the smallest conductor is 14 AWG copper; 18 and 16 AWG are permitted only for specific limited applications such as fixture wire and some Class 2 circuits. See NEC 310.106(A) and Table 310.16.

At least one required 125-volt receptacle serving a permanently installed pool must be located within what distance range from the inside pool wall?

• a.Between 10 feet and 25 feet
• b.Between 6 feet and 20 feet✓
• c.Between 5 feet and 15 feet
• d.Between 3 feet and 10 feet

A general-use receptacle must be no closer than 6 feet, and at least one required receptacle must be located between 6 and 20 feet from the inside pool wall. See NEC 680.22(A).

A location where combustible dust is present in ignitible concentrations is classified as which type?

• a.Class IV
• b.Class II✓
• c.Class I
• d.Class III

Class II locations are those made hazardous by combustible dust. Class I covers flammable gases and vapors and Class III covers ignitible fibers and flyings. See NEC 500.5(C).

A 15-ampere, 125-volt receptacle is installed in a damp location such as under a roofed open porch. What cover is required?

• a.A cover that is weatherproof when no attachment plug is inserted✓
• b.A cover that is weatherproof whether or not a plug is inserted
• c.No cover is required in a damp location
• d.A standard indoor wall plate

In damp locations a receptacle needs an enclosure weatherproof when a plug is not inserted; the stricter in-use cover, weatherproof with a plug inserted, is required in wet locations. See NEC 406.9(A).

Receptacles installed outdoors in wet or damp locations must be which listed type?

• a.Twist-lock
• b.Weather-resistant✓
• c.Hospital-grade
• d.Isolated-ground

Fifteen- and 20-ampere, 125- and 250-volt receptacles in damp or wet locations must be listed weather-resistant. See NEC 406.9(A) and 406.9(B).

Which of the following is a recognized equipment grounding conductor?

• a.Electrical nonmetallic tubing
• b.Rigid metal conduit installed under its article✓
• c.A nonmetallic pull string
• d.Rigid PVC conduit

Metal raceways such as rigid metal conduit, intermediate metal conduit and EMT are recognized equipment grounding conductors; nonmetallic raceways are not. See NEC 250.118.

Rigid PVC conduit requires an expansion fitting where the expected length change due to temperature is at least what value?

• a.1/8 inch
• b.1 inch
• c.1/2 inch
• d.1/4 inch✓

Expansion fittings are required for PVC conduit where the length change is expected to be 1/4 inch or more. See NEC 352.44.

How many 12 AWG conductors may be installed in a 21.0-cubic-inch box with no clamps, devices or fittings?

• a.8
• b.10
• c.9✓
• d.11

Each 12 AWG conductor requires 2.25 cubic inches: 21.0 / 2.25 = 9.33, rounded down to 9 conductors. See NEC 314.16(A) and (B).

What is the maximum permitted conductor fill of a metal wireway?

• a.31 percent
• b.53 percent
• c.20 percent✓
• d.40 percent

The conductors in a metal wireway may not fill more than 20 percent of its interior cross-sectional area. See NEC 376.22(A).

A raceway enters a building underground from an outside source. What is required at the point of entry?

• a.It must be sealed or plugged to prevent moisture from entering the building✓
• b.It must be left open for ventilation
• c.It must be filled completely with concrete
• d.It must be bonded but is never sealed

Conduits and raceways entering a building underground must be sealed or plugged with an identified compound to stop moisture and gases from entering. See NEC 300.5(G).

Type NM cable entering a single-gang nonmetallic box that has no cable clamps must be secured within what distance of the box?

• a.24 inches
• b.8 inches✓
• c.3 feet
• d.4 and 1/2 feet

Where a single-gang nonmetallic box without internal clamps is used, the NM cable must be secured within 8 inches of the box. See NEC 314.17(C) Exception and 334.30(A).

May a raceway be used as a means of support for another raceway or box?

• a.Yes, in all cases
• b.Yes, for spans under 6 feet
• c.Only where the raceway is nonmetallic
• d.No, except where the raceway is identified for that purpose or specifically permitted✓

Raceways may not be used to support other raceways, cables or nonelectrical equipment unless identified for the purpose or specifically permitted. See NEC 300.11(C).

A junction box contains four 12 AWG and three 10 AWG conductors with no devices, clamps or fittings. What minimum box volume is required?

• a.16.5 cubic inches✓
• b.17.5 cubic inches
• c.14.0 cubic inches
• d.15.75 cubic inches

Each conductor is counted at the allowance for its own size: four 12 AWG at 2.25 = 9.0, and three 10 AWG at 2.50 = 7.5, for 16.5 cubic inches. See NEC 314.16(B)(1).

What is the minimum trade size of EMT required for six 10 AWG THHN conductors?

• a.One inch
• b.Three-quarter inch✓
• c.One-half inch
• d.One and one-quarter inch

Annex C, Table C1 shows one-half-inch EMT holds five 10 AWG THHN and three-quarter-inch EMT holds ten, so three-quarter inch is the minimum for six. See NEC Annex C, Table C1.

A metal outlet box is supplied by a wiring method that includes an equipment grounding conductor. How must the box be treated?

• a.It must be left isolated from ground
• b.It must be connected to the grounded neutral bar
• c.It must be connected to the equipment grounding conductor✓
• d.It need be bonded only in a wet location

A metal box must be connected to an equipment grounding conductor so it is bonded and any fault will clear. See NEC 250.148 and 314.4.

An insulated bushing or fitting to protect conductors from abrasion is required where conductors of what size or larger enter a raceway or enclosure?

• a.1 AWG
• b.4 AWG✓
• c.8 AWG
• d.6 AWG

Where ungrounded conductors of 4 AWG or larger enter a raceway in a cabinet, box or enclosure, a fitting providing a smoothly rounded insulating surface, such as an insulating bushing, is required. See NEC 300.4(G).

In box-fill calculations, how is a device yoke or strap counted?

• a.As two conductor volume allowances, based on the largest conductor connected to the device✓
• b.It is not counted at all
• c.As one conductor volume allowance
• d.As two allowances, based on the smallest conductor

Each yoke or strap containing a device or utilization equipment is counted as two conductor volume allowances based on the largest conductor connected to it. See NEC 314.16(B)(4).