Free 80-Question NEC Practice Test — Journeyman Exam Prep

Question 1 · Branch Circuits & Feeders · moderate

A branch circuit serves a 24-ampere continuous load and no other load. Before applying any adjustment or correction factors, the branch-circuit conductors must have an ampacity of at least what value?

NEC 2023 210.19(A)(1) — 210.19(A)(1)(a): the minimum conductor ampacity is the noncontinuous load plus 125 percent of the continuous load, so 24 x 1.25 = 30 A. Choice A omits the 125 percent factor.

Question 2 · Equipment for General Use · moderate

An existing receptacle is being replaced at a location where GFCI protection is now required by 210.8. What does 406.4(D) require of the replacement receptacle?

NEC 2023 406.4(D)(3) — 406.4(D)(3) requires that where a receptacle is replaced at a location that now requires GFCI protection, the replacement be provided with GFCI protection.

Question 3 · General Theory & Definitions · moderate

A heating element with a resistance of 20 ohms is connected to a 120-volt source. Ignoring temperature effects, what current flows through the element?

Electrical theory - Ohm's law — By Ohm's law, I = E / R = 120 V / 20 ohms = 6 A. Choice D results from multiplying instead of dividing (120 x 20); the others come from using an incorrect resistance value.

Question 4 · Grounding & Bonding · moderate

The GEC for a large service connects solely to a concrete-encased (Ufer) electrode. What is the largest copper GEC size the Code requires you to run to that electrode?

NEC 2023 250.66(B) — Where the GEC connects only to a concrete-encased electrode, that portion need not be larger than 4 AWG copper. The 6 AWG allowance applies to rod/pipe/plate electrodes, not the concrete-encased electrode.

Question 5 · Overcurrent Protection · moderate

Conductors with an allowable ampacity of 95 A protect a feeder that meets all conditions of the next-higher-standard-rating rule. What is the maximum standard overcurrent device rating permitted?

NEC 2023 240.4(B) — 95 A is not a standard rating and sits between 90 and 100; the next higher standard rating permitted under 240.4(B) is 100 A.

Question 6 · Services · moderate

Overhead service conductors cross above a public street that is subject to truck traffic. What is the minimum required vertical clearance?

NEC 2023 230.24(B)(4) — 230.24(B)(4) requires 18 ft over public streets, alleys, roads, and areas subject to truck traffic. The 12 ft value is for residential property and driveways; 10 ft is the pedestrian-only value.

Question 7 · Special Equipment & Conditions · moderate

The equipotential bonding for a permanently installed pool must include the perimeter surfaces around the pool. Measured horizontally beyond the inside walls of the pool, how far do these bonded perimeter surfaces extend?

NEC 2023 680.26(B)(2) — 680.26(B)(2) defines the perimeter surface as extending 3 ft horizontally beyond the inside walls of the pool, and it must be part of the equipotential bonding. The other values do not match the Code dimension.

Question 8 · Special Occupancies · moderate

During a walkthrough of an aircraft hangar you find a floor-level maintenance pit dug beneath where aircraft sit so workers can reach the underside of the airframe. Which hazardous (classified) location designation applies inside that pit?

NEC 2023 513.3(A) — 513.3(A) classifies any pit or depression below the level of the hangar floor as Class I, Division 1, since heavier-than-air vapors collect in such low spaces.

Question 9 · Wiring Methods & Materials · moderate

Using Annex C, Table C.1, how many 12 AWG THHN conductors (all the same size) are permitted in a 3/4 in. trade size EMT?

NEC 2023 Annex C, Table C.1 — Annex C, Table C.1 (EMT, THHN): 3/4 in. EMT holds 16 twelve-AWG conductors. The value 9 is for 1/2 in. EMT and 22 is the count for 14 AWG in 3/4 in. EMT.

Question 10 · Branch Circuits & Feeders · easy

In a dwelling family room, general receptacle placement is governed by the rule that no point measured horizontally along the floor line of any wall space may be more than a stated distance from a receptacle outlet. What is that distance?

NEC 2023 210.52(A)(1) — 210.52(A)(1) sets the 1.8 m (6 ft) point-to-receptacle limit so a 1.8 m appliance cord reaches from either side. The 12 ft figure is the resulting maximum spacing between two outlets, not the distance from a point to a receptacle.

Question 11 · Equipment for General Use · easy

A wall-mounted general-use snap switch is being installed in a finished basement. Measured to the center of the grip of the operating handle in its highest position, what is the maximum height above the finished floor or working platform permitted?

NEC 2023 404.8(A) — 404.8(A) limits the center of the operating-handle grip, in its highest position, to a maximum of 6 ft 7 in (2.0 m) above the floor or working platform.

Question 12 · General Theory & Definitions · easy

According to Article 90, what is the stated purpose of the National Electrical Code?

NEC 2023 90.1(A) — 90.1(A) states the Code's purpose is the practical safeguarding of persons and property from hazards arising from the use of electricity. 90.1(B) says it is NOT a design specification or instruction manual, and 90.1(C) notes it is not necessarily adequate for future expansion or good service.

Question 13 · Grounding & Bonding · easy

A ground rod is being installed as the sole made electrode for a residence. What is the minimum length of rod that must be in contact with the soil?

NEC 2023 250.52(A)(5) and 250.53(G) — Rod-type electrodes must be at least 8 ft long and installed so at least 8 ft is in contact with the soil. The other lengths are plausible but incorrect values.

Question 14 · Overcurrent Protection · easy

A 14 AWG copper branch-circuit conductor is being protected. Disregarding the special-application exceptions of 240.4(E) and (G), the overcurrent device protecting it may be rated no higher than which value?

NEC 2023 240.4(D)(3) — The small-conductor rule caps overcurrent protection for 14 AWG copper at 15 A regardless of its table ampacity.

Question 15 · Services · easy

A service disconnecting means for a dwelling may be installed in each of the following locations EXCEPT which one?

NEC 2023 230.70(A)(2) — 230.70(A)(2) prohibits installing the service disconnecting means in a bathroom. The other listed locations are permissible provided the disconnect is readily accessible.

Question 16 · Special Equipment & Conditions · easy

While roughing in a permanently installed outdoor pool, an electrician ties the conductive pool shell, the perimeter surfaces, and the metal fittings together with the common equipotential bonding conductor. What is the minimum size and type of copper conductor the Code permits for this bonding connection?

NEC 2023 680.26(B) — 680.26(B) requires the parts to be connected with a solid copper conductor not smaller than 8 AWG. Stranded 8 AWG does not satisfy the 'solid' requirement, and 6 or 10 AWG are the wrong size.

Question 17 · Special Occupancies · easy

A processing room contains suspended metal powder that can ignite when airborne. Under the NEC classification scheme, which hazardous (classified) location Class is defined by the presence of this hazard?

NEC 2023 500.5(C) — Class II locations are those made hazardous by the presence of combustible dust, per 500.5(C). Class I covers flammable gases/vapors and Class III covers ignitible fibers/flyings; there is no Class IV.

Question 18 · Wiring Methods & Materials · easy

Type NM cable installed on the surface of framing members must be secured within what distance of each outlet box or cabinet, and supported at what maximum interval along the run?

NEC 2023 334.30 — 334.30 requires Type NM cable to be secured within 12 in. of every box/cabinet and supported at intervals not exceeding 4-1/2 ft. The 6 ft interval belongs to Type MC (330.30).

Question 19 · Branch Circuits & Feeders · difficult

A feeder supplies a 200-ampere noncontinuous load plus a 100-ampere continuous load. With 75C terminations and no ampacity adjustment factors applied, what minimum conductor ampacity must the feeder have?

NEC 2023 215.2(A)(1) — 215.2(A)(1): 200 + (100 x 1.25) = 325 A. Choice A applies 100 percent to the continuous load; choice B applies 125 percent to the entire 300 A.

Question 20 · Equipment for General Use · difficult

A recessed luminaire that is NOT identified for contact with insulation (not Type IC) is installed in an insulated ceiling. What minimum spacing must be maintained between thermal insulation and the luminaire enclosure, wiring compartment, and ballast?

NEC 2023 410.116(B) — 410.116(B) requires that thermal insulation not be installed within 3 in of a recessed luminaire enclosure, wiring compartment, or ballast unless the luminaire is identified for insulation contact (Type IC).

Question 21 · General Theory & Definitions · difficult

A switchboard rated 1000 amperes is 8 ft wide and requires examination while energized. Which statement correctly describes the entrance and egress requirement for its working space?

NEC 2023 110.26(C)(2) — 110.26(C)(2) requires equipment rated 800 A or more and over 6 ft wide to have an entrance not less than 24 in. wide and 6 1/2 ft high at each end of the working space (with limited exceptions). The 1200 A figure was the older threshold before it was lowered to 800 A.

Question 22 · Grounding & Bonding · difficult

A service uses two parallel sets of 600 kcmil copper conductors per phase, connected to a metal water pipe electrode. What is the minimum size copper grounding electrode conductor?

NEC 2023 Table 250.66 — For parallel conductors, Table 250.66 is applied to the equivalent area: 2 x 600 = 1200 kcmil per phase, which is over 1100 kcmil. That range requires a 3/0 AWG copper GEC. Sizing from a single 600 kcmil conductor is the common error.

Question 23 · Overcurrent Protection · difficult

A branch circuit supplying several receptacles for cord-and-plug-connected portable loads uses conductors with an allowable ampacity of 34 A. What is the maximum standard overcurrent device rating permitted?

NEC 2023 240.4(B) — The next-higher-standard allowance is not permitted because condition (1) of 240.4(B) excludes branch circuits supplying more than one receptacle for cord-and-plug portable loads. So you cannot round up to 35 A; the device must not exceed the next lower standard rating, 30 A.

Question 24 · Services · difficult

A service supplies a 100 A noncontinuous load and a 120 A continuous load. Using 230.42(A)(1), what is the minimum required ampacity of the service-entrance conductors?

NEC 2023 230.42(A)(1) — 230.42(A)(1) requires the sum of the noncontinuous load plus 125 percent of the continuous load: 100 + (1.25 x 120) = 100 + 150 = 250 A.

Question 25 · Special Equipment & Conditions · difficult

A rooftop PV array on a commercial building has a rapid-shutdown system. Upon initiation of rapid shutdown, the controlled conductors located inside the array boundary must be reduced to what maximum voltage within 30 seconds?

NEC 2023 690.12(B)(2) — 690.12(B)(2) requires controlled conductors inside the array boundary to be limited to not more than 80 volts within 30 seconds of rapid-shutdown initiation. The 30-volt value applies to conductors outside the array boundary, not inside it.

Question 26 · Special Occupancies · difficult

A parked aircraft in a hangar has integral fuel tanks and power plants. Measured horizontally outward from the aircraft power plants and fuel tanks, the surrounding air is classified as Class I, Division 2. What horizontal distance does this vicinity-of-aircraft classification extend?

NEC 2023 513.3(C) — 513.3(C) classifies the area within 5 ft horizontally of aircraft power plants or aircraft fuel tanks as Class I, Division 2 (or Zone 2), extending upward from that area as specified.

Question 27 · Wiring Methods & Materials · difficult

In a junction box containing 4 AWG and larger conductors, the minimum length for a straight pull must be at least how many times the trade diameter of the largest raceway?

NEC 2023 314.28(A)(1) — 314.28(A)(1): for straight pulls the box length must be at least 8 times the trade diameter of the largest raceway. The 6-times factor applies to angle and U pulls under 314.28(A)(2).

Question 28 · Branch Circuits & Feeders · moderate

A feeder supplies a continuous load of 160 amperes and a noncontinuous load of 40 amperes. Ignoring any ampacity adjustment or correction factors, what is the minimum required feeder conductor ampacity?

NEC 2023 215.2(A)(1) — 215.2(A)(1): 40 + (160 x 1.25) = 240 A. Choice A treats the continuous load at 100 percent.

Question 29 · Equipment for General Use · moderate

A panelboard is supplied from a 4-wire, delta-connected system that has one phase with a higher voltage to ground. How must that high-leg conductor be arranged and identified at the panelboard?

NEC 2023 408.3(E)(1) — 408.3(E)(1) places the higher-voltage-to-ground (high) leg on phase B in the busbar arrangement, and 110.15 requires that conductor be durably and permanently marked by an orange color or other effective means.

Question 30 · General Theory & Definitions · moderate

A load draws 10 amperes from a 120-volt single-phase circuit. Using P = I x E, what is the power consumed?

Electrical theory - power (P = I x E) — Power equals current times voltage: P = I x E = 10 A x 120 V = 1200 W. Choice A divides, choice B adds, and choice C squares the current instead of applying the correct formula.

Question 31 · Grounding & Bonding · moderate

Two rod electrodes are installed to form a grounding electrode system. What is the minimum spacing required between them?

NEC 2023 250.53(A)(3) — Where more than one rod, pipe, or plate electrode is used, each must be at least 6 ft apart. The 8 ft distractor mirrors the rod length, a common source of confusion.

Question 32 · Overcurrent Protection · moderate

A set of feeder conductors has an allowable ampacity of exactly 100 A. What is the maximum standard overcurrent device rating permitted to protect them?

NEC 2023 240.4(B) — The next-higher-standard allowance applies only when the conductor ampacity does not correspond to a standard rating. Because 100 A is itself a standard rating, you cannot round up; the maximum is 100 A.

Question 33 · Services · moderate

Open service conductors run alongside a wall must maintain a minimum clearance from a window designed to be opened. What is that clearance?

NEC 2023 230.9(A) — 230.9(A) requires a clearance of not less than 3 ft from windows that open, doors, porches, balconies, and similar locations. Conductors run above the top level of a window are exempt from this clearance.

Question 34 · Special Equipment & Conditions · moderate

An illuminated channel-letter sign is mounted on the parapet of a retail building, and its controller sits on the roof. Where must the disconnecting means for the sign be installed?

NEC 2023 600.6(A)(1) — 600.6(A)(1) requires the disconnecting means to be within sight of the sign or the controller it controls; where not within sight, it must be capable of being locked in the open position. Location at the service or a same-floor location does not satisfy the within-sight/lockable rule.

Question 35 · Special Occupancies · moderate

Across the general floor area of an aircraft hangar (not near the aircraft itself), a Class I, Division 2 classification applies from the floor upward to a fixed height. What is that height above the floor?

NEC 2023 513.3(B) — 513.3(B) classifies the entire hangar floor area, including adjacent and communicating areas, as Class I, Division 2 up to a level 18 in. above the floor.

Question 36 · Wiring Methods & Materials · moderate

In a box-fill calculation, how is a single duplex receptacle (a device on a yoke) counted, and on what conductor size is that allowance based?

NEC 2023 314.16(B)(4) — 314.16(B)(4): each yoke or strap containing one or more devices is counted as two volume allowances based on the largest conductor connected to the device.

Question 37 · Branch Circuits & Feeders · easy

What is the minimum number of 20-ampere small-appliance branch circuits required to supply the receptacle outlets in a dwelling kitchen, pantry, breakfast room, and dining room?

NEC 2023 210.11(C)(1) — 210.11(C)(1) requires at least two 20 A small-appliance branch circuits to serve those areas; these are in addition to the required laundry and bathroom circuits.

Question 38 · Equipment for General Use · easy

In a new dwelling unit, the 15- and 20-ampere, 125-volt nonlocking receptacles installed in the required locations must be what type?

NEC 2023 406.12 — 406.12 requires all 15- and 20-ampere, 125- and 250-volt nonlocking receptacles in the listed dwelling-unit areas to be listed tamper-resistant.

Question 39 · General Theory & Definitions · easy

Per the Article 100 definition, which description best matches a dwelling unit?

NEC 2023 Article 100 (Dwelling Unit) — Article 100 defines a dwelling unit as a single unit providing complete and independent living facilities for one or more persons, including permanent provisions for living, sleeping, cooking, and sanitation. Choice D describes a two-family dwelling.

Question 40 · Grounding & Bonding · easy

A galvanized (iron or steel) rod electrode that is not listed must have a minimum diameter of what dimension?

NEC 2023 250.52(A)(5)(b) — Nonlisted iron or steel rods must be at least 5/8 in. in diameter. The 1/2 in. value applies only to listed rods and to stainless steel or nonferrous rods, which is a common point of confusion.

Question 41 · Overcurrent Protection · easy

Leaving aside the specific applications addressed in 240.4(G), a 12 AWG copper conductor may be protected by an overcurrent device rated no greater than which value?

NEC 2023 240.4(D)(5) — The small-conductor rule fixes the ceiling for 12 AWG copper at 20 A. The 15 A value belongs to 12 AWG aluminum, not copper.

Question 42 · Services · easy

Where does the NEC require the service disconnecting means to be located?

NEC 2023 230.70(A)(1) — 230.70(A)(1) requires the service disconnect at a readily accessible location, outside or inside nearest the point of entrance of the service conductors. No fixed inside distance is specified, and either location is allowed.

Question 43 · Special Equipment & Conditions · easy

A one-family dwelling has a permanently installed pool. The required maintenance disconnecting means for the pool utilization equipment must be readily accessible, within sight of the equipment, and located what minimum horizontal distance from the inside walls of the pool, unless separated by a permanent barrier?

NEC 2023 680.13 — 680.13 requires the maintenance disconnecting means to be readily accessible, within sight from the equipment, and at least 5 ft horizontally from the inside walls of the pool, spa, or hot tub unless separated by a permanent barrier. The other distances are near-misses.

Question 44 · Special Occupancies · easy

A commercial parking garage is used only for the parking and storage of vehicles, with no repair or servicing performed on the premises. How does Article 511 treat the electrical classification of this occupancy?

NEC 2023 511.3 — Under 511.3, parking garages used solely for parking or storage are permitted to be unclassified. Classified areas arise only where major or minor repair operations are performed.

Question 45 · Wiring Methods & Materials · easy

Electrical metallic tubing (EMT) must be securely fastened within what distance of each outlet box, junction box, or fitting, and supported at what maximum interval?

NEC 2023 358.30(A) — 358.30(A) requires EMT to be fastened within 3 ft of each termination and supported at intervals not exceeding 10 ft.

Question 46 · Branch Circuits & Feeders · difficult

A branch circuit supplies a single continuous load of 44 amperes. Applying the standard overcurrent device sizes of 240.6(A), what is the minimum standard OCPD rating permitted?

NEC 2023 210.20(A) — 210.20(A): 44 x 1.25 = 55 A. But 55 A is not a standard size in 240.6(A), so the next standard size up, 60 A, is the minimum. Choice C forgets the 125 percent factor.

Question 47 · Equipment for General Use · difficult

A 25-horsepower, 460-volt, three-phase continuous-duty motor is installed. Using the full-load current from Table 430.250, what is the minimum ampacity of the branch-circuit conductors?

NEC 2023 Table 430.250 — Table 430.250 lists 34 A for a 25 hp, 460 V three-phase motor; 430.22(A) requires 125 percent: 34 A x 1.25 = 42.5 A.

Question 48 · General Theory & Definitions · difficult

An electrician cites the NEC's 3 percent branch-circuit voltage-drop figure to a customer. Which statement most accurately reflects how the Code treats this value?

NEC 2023 210.19 Informational Note (voltage drop) — The 3 percent branch-circuit / 5 percent combined voltage-drop figures appear in Informational Notes to 210.19 and 215.2. Informational Notes are explanatory and not enforceable requirements (per 90.5(C)), so voltage drop is a design recommendation, not a mandatory limit for general circuits.

Question 49 · Grounding & Bonding · difficult

A service is supplied with a single 1500 kcmil copper conductor per phase. What is the minimum size copper main bonding jumper?

NEC 2023 Table 250.102(C)(1), Note 1 — Where ungrounded conductors exceed 1100 kcmil copper, the bonding jumper must be at least 12.5 percent of the largest ungrounded conductor area. 12.5 percent of 1500 kcmil is 187.5 kcmil, so the next standard conductor of at least that area is 4/0 AWG (211.6 kcmil). 3/0 (167.8 kcmil) is too small.

Question 50 · Overcurrent Protection · difficult

Which of the following is an actual requirement of the 10-foot feeder tap rule, as opposed to the 25-foot tap rule?

NEC 2023 240.21(B)(1) — The 10-times-ampacity limit on the line-side device is unique to the 10-foot tap rule. The 25-ft length, the single-device termination, and the one-third-ampacity requirement all belong to the 25-foot tap rule instead.

Question 51 · Services · difficult

Ground-fault protection of equipment is required for which of the following service disconnecting means?

NEC 2023 230.95 — 230.95 requires ground-fault protection on solidly grounded wye services of more than 150 volts to ground but not exceeding 1000 volts phase-to-phase, for each disconnect rated 1000 A or more. A 480Y/277 V (277 V to ground) service at 1200 A meets all conditions; the 208Y/120 V system is only 120 V to ground, and the 800 A disconnect is below the 1000 A threshold.

Question 52 · Special Equipment & Conditions · difficult

In a commercial installation, an electrician wants to run Class 2 control conductors in the same raceway as 120-volt power branch-circuit conductors to save on conduit. Under the general rule, what does the Code require?

NEC 2023 725.136 — 725.136 generally prohibits Class 2 conductors from occupying the same cable, raceway, or enclosure as electric light, power, or Class 1 conductors unless one of the recognized separation methods or exceptions applies. Being power-limited or a certain gauge does not by itself permit mixing.

Question 53 · Special Occupancies · difficult

At a gasoline dispensing island, consider the outdoor volume lying within 18 in. of grade around a dispenser. Out to what horizontal distance from the dispenser enclosure does the Class I, Division 2 classification reach at that low level?

NEC 2023 Table 514.3(B)(1) — Table 514.3(B)(1) classifies the outdoor area up to 18 in. above grade extending 20 ft horizontally from the dispenser enclosure as Class I, Division 2.

Question 54 · Wiring Methods & Materials · difficult

Conductor ampacity adjustment (derating) factors for a metal wireway are required only when the number of current-carrying conductors at any cross-section exceeds what value?

NEC 2023 376.22(B) — 376.22(B): the adjustment factors of 310.15(C)(1) apply only where the number of current-carrying conductors in the wireway exceeds 30 (the neutral rules of 310.15(E) still apply).

Question 55 · Branch Circuits & Feeders · moderate

A 20-ampere multiple-outlet branch circuit supplies several receptacles. What receptacle ampere rating(s) may be installed on that circuit?

NEC 2023 Table 210.21(B)(3) — Table 210.21(B)(3) permits both 15 A and 20 A receptacles on a 20 A branch circuit. A single receptacle on an individual circuit would instead have to match the circuit rating under 210.21(B)(1).

Question 56 · Equipment for General Use · moderate

A lighting and appliance panelboard has a 225-ampere busbar rating. Absent any applicable exception, what is the maximum rating of the overcurrent device protecting that panelboard?

NEC 2023 408.36 — 408.36 requires each panelboard to be individually protected by an overcurrent device having a rating not greater than that of the panelboard, so a 225 A busbar is limited to a 225 A device.

Question 57 · General Theory & Definitions · moderate

Three 10-ohm resistors are connected in series. What is the total resistance of the combination?

Electrical theory - series resistance — In a series circuit, resistances add: 10 + 10 + 10 = 30 ohms. Choice A is the result of a parallel calculation (10/3), which does not apply to series connections.

Question 58 · Grounding & Bonding · moderate

A concrete-encased electrode is being formed using steel reinforcing bar in a foundation footing. What is the minimum requirement for the rebar electrode?

NEC 2023 250.52(A)(3) — A concrete-encased electrode must be at least 20 ft of 1/2 in. (No. 4) or larger bare steel bars, or 20 ft of bare copper not smaller than 4 AWG, encased in at least 2 in. of concrete near the earth. The other options fall short on length or conductor size.

Question 59 · Overcurrent Protection · moderate

A 12 AWG copper THHN conductor has a 90 C table ampacity of 30 A, but after ambient temperature and conduit-fill correction its corrected ampacity works out to about 24 A. What is the maximum overcurrent device rating permitted?

NEC 2023 240.4(D)(5) — The small-conductor rule is applied after correction factors and still caps 12 AWG copper at 20 A. The corrected 24 A ampacity does not raise the ceiling; you do not round it up to 25 A.

Question 60 · Services · moderate

Underground service conductors supplying a normal load must not be smaller than what minimum copper size?

NEC 2023 230.31(B) — 230.31(B) requires underground service conductors to be not smaller than 8 AWG copper or 6 AWG aluminum. The 6 AWG figure is the aluminum minimum, not the copper minimum; 230.31(C) covers the neutral, not the ungrounded minimum size.

Question 61 · Special Equipment & Conditions · moderate

For each elevator, the disconnecting means that opens all ungrounded main power-supply conductors must be a specific type of device. Which option meets the Code requirement?

NEC 2023 620.51 — 620.51 requires the elevator main power disconnecting means to be an enclosed, externally operable fused motor-circuit switch or circuit breaker that can be locked in the open position. Cord-and-plug and non-lockable pull-outs do not qualify, and an in-car snap switch is not the main disconnect.

Question 62 · Special Occupancies · moderate

Emergency shutoff devices (disconnects) at a motor fuel dispensing facility must cut power to the dispensing equipment from an approved remote location. What distance range from the dispensers does the NEC specify for the location of these devices?

NEC 2023 514.11(A) — 514.11(A) requires emergency shutoff devices or disconnects to be installed at approved locations not less than 20 ft and not more than 100 ft from the fuel dispensing devices they serve, so they are reachable yet clear of a fire at the island.

Question 63 · Wiring Methods & Materials · moderate

Conductors with 75 degrees C insulation are installed where the ambient temperature is 48 degrees C. What temperature correction factor applies per Table 310.15(B)(1)?

NEC 2023 Table 310.15(B)(1) — Table 310.15(B)(1), 75 degrees C column, ambient 46-50 degrees C, gives a correction factor of 0.75. The 41-45 degrees C row is 0.82 and 36-40 degrees C is 0.88.

Question 64 · Branch Circuits & Feeders · easy

At least one branch circuit must be provided to supply the receptacle outlet(s) required in a dwelling bathroom. What is the minimum rating of that branch circuit?

NEC 2023 210.11(C)(3) — 210.11(C)(3) requires at least one 20 A branch circuit for bathroom receptacle outlets; a 15 A circuit does not satisfy the rule.

Question 65 · Equipment for General Use · easy

Measured vertically from the top of the bathtub rim, what is the height of the zone in which luminaires (not listed for damp or wet locations) are prohibited above a bathtub?

NEC 2023 410.10(D) — 410.10(D) establishes a prohibited zone extending 3 ft horizontally and 8 ft vertically from the top of the bathtub rim or shower stall threshold unless the equipment is listed for damp or wet locations.

Question 66 · General Theory & Definitions · easy

What is the minimum height (headroom) of the working space required in front of electrical equipment likely to be serviced while energized?

NEC 2023 110.26(A)(3) — 110.26(A)(3) requires the working-space headroom to be at least 6 1/2 ft (2.0 m), or the height of the equipment where it is taller. Choice D is a working-space depth dimension, not height.

Question 67 · Grounding & Bonding · easy

A single ground rod is used as the grounding electrode. Above what measured resistance to earth must a supplemental electrode be added?

NEC 2023 250.53(A)(2) Exception — A single rod, pipe, or plate electrode that does not achieve 25 ohms or less to earth must be supplemented by one additional electrode. If it is 25 ohms or less, no supplement is required.

Question 68 · Overcurrent Protection · easy

Under the small-conductor provision, the overcurrent device protecting a 10 AWG copper conductor may not exceed which standard rating?

NEC 2023 240.4(D)(7) — The small-conductor rule caps 10 AWG copper at 30 A. The 25 A value corresponds to 10 AWG aluminum, not copper.

Question 69 · Services · easy

For a one-family dwelling served by a 3-wire service, the service disconnecting means must have a rating of not less than what value?

NEC 2023 230.79(C) — 230.79(C) sets the minimum service disconnect rating for a one-family dwelling at 100 A, 3-wire. The 60 A floor applies to all other installations under 230.79(D).

Question 70 · Wiring Methods & Materials · easy

At each point where conductors are spliced, tapped, or terminated in a raceway wiring method, the Code generally requires the installation of what?

NEC 2023 300.15 — 300.15 requires a box or conduit body (or other listed enclosure) at each conductor splice, outlet, switch, junction, or pull point for raceway and cable systems.

Question 71 · Branch Circuits & Feeders · difficult

Under the 2023 NEC, a cord-and-plug-connected 120/240-volt electric range in a dwelling is supplied by a 40-ampere branch circuit. Does it require GFCI protection, and why?

NEC 2023 210.8(D) — 210.8(D) in the 2023 NEC requires GFCI protection for listed appliances, including electric ranges, rated 150 V or less to ground and 60 A or less. A 120/240 V range is 120 V to ground and the 40 A circuit is at or below 60 A, so protection is required. The 240 V nominal value does not exceed the 150 V-to-ground criterion.

Question 72 · Equipment for General Use · difficult

A 10-horsepower, 230-volt, three-phase motor is protected by a non-time-delay fuse for branch-circuit short-circuit and ground-fault protection. Applying Table 430.52 and permitting the next standard size where the calculated value is not standard, what is the maximum standard fuse rating?

NEC 2023 Table 430.52 — Table 430.250 gives 28 A for a 10 hp, 230 V three-phase motor; a non-time-delay fuse is 300 percent (28 x 3.00 = 84 A). Because 84 A is not a standard size, 430.52(C)(1) Exception No. 1 permits the next standard size, 90 A.

Question 73 · Grounding & Bonding · difficult

A 200 A feeder would normally use 3/0 AWG copper ungrounded conductors, but they are upsized to 250 kcmil copper for voltage drop. What is the minimum size copper equipment grounding conductor after adjustment?

NEC 2023 250.122(B) — Base EGC for 200 A is 6 AWG (26,240 cmil). The ungrounded conductors increased from 167,800 to 250,000 cmil, a ratio of about 1.49. 26,240 x 1.49 is about 39,100 cmil, so the EGC must be at least 4 AWG (41,740 cmil). Leaving it at 6 AWG ignores the 250.122(B) adjustment.

Question 74 · Services · difficult

Not more than 6 ft of service-drop conductors at 120/240 V pass over not more than 4 ft of a roof overhang and terminate at a through-the-roof raceway support. What is the minimum vertical clearance above the roof overhang for this arrangement?

NEC 2023 230.24(A) Exception No. 3 — The 230.24(A) Exception for a roof overhang permits reducing the clearance to 18 in. when not more than 6 ft of conductor passes over not more than 4 ft of overhang and terminates at a through-the-roof raceway or approved support. The 8 ft value is the general rule; 3 ft is the roof-slope exception.

Question 75 · Wiring Methods & Materials · difficult

Twelve current-carrying 6 AWG THHN copper conductors share one raceway in a 38 degrees C ambient. Starting from the 90 degrees C ampacity of 75 A, applying the conductor-count adjustment and the temperature correction, the adjusted ampacity is closest to which value?

NEC 2023 Table 310.15(C)(1) and Table 310.15(B)(1) — 10-20 conductors require a 50% adjustment (Table 310.15(C)(1)); the 90 degrees C correction at 36-40 degrees C is 0.91 (Table 310.15(B)(1)). 75 x 0.50 x 0.91 = 34.1 A. Omitting either factor gives 68 A or 38 A.

Question 76 · Branch Circuits & Feeders · moderate

In the non-dwelling locations listed in 210.8(B), receptacles supplied by three-phase branch circuits rated 150 volts to ground or less require GFCI protection up to what maximum ampere rating?

NEC 2023 210.8(B) — 210.8(B) sets 50 A for single-phase and 100 A for three-phase receptacles at 150 V to ground or less. Choice A is the single-phase threshold, not the three-phase one.

Question 77 · Equipment for General Use · moderate

A surface-mounted incandescent luminaire with a completely enclosed light source is to be installed in a clothes closet. What is the minimum clearance required between the luminaire and the nearest point of the defined storage space?

NEC 2023 410.16(C)(1) — 410.16(C)(1) requires a minimum 12 in clearance between the storage space and a surface-mounted incandescent or LED luminaire with a completely enclosed light source.

Question 78 · Wiring Methods & Materials · moderate

In a normal 3-wire, single-phase circuit, a neutral conductor that carries only the unbalanced current from the other conductors is counted how for conductor-adjustment purposes?

NEC 2023 310.15(E)(1) — 310.15(E)(1): a neutral carrying only the unbalanced current from other conductors is not counted as a current-carrying conductor when applying adjustment factors.

Question 79 · Wiring Methods & Materials · easy

For a 0-1000V direct-buried cable installed in a general location (not under a building, roadway, or the residential exceptions), what is the minimum burial cover per Table 300.5(A)?

NEC 2023 Table 300.5(A) — Table 300.5(A), Column 1 (direct-buried cables/conductors), general locations, requires 24 in. of cover. 12 in. applies only to the residential 120V/20A GFCI-protected branch-circuit column.

Question 80 · Wiring Methods & Materials · difficult

A device box contains six 12 AWG current-carrying conductors, one 12 AWG equipment grounding conductor, one or more internal cable clamps, and one duplex receptacle (all conductors 12 AWG). What is the minimum required box volume?

NEC 2023 314.16(B) — At 2.25 cu in. per 12 AWG: six conductors = 6, grounding (all together) = 1, clamps (all together) = 1, device yoke = 2, total 10 allowances. 10 x 2.25 = 22.50 cu in. Omitting the clamp gives 20.25.

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