20 original practice questions. Pick an answer to see whether you were right, why, and which code section it comes from.
The real exam is 77 questions in 4 hours, open book, with a passing score of 70%.
Based on: NEC 2023.
0 of 20 answered
Question 1 of 20
Within what distance of every box, cabinet, or fitting must Type NM cable be secured, absent a listed cable connector that provides support?
Not quite. The answer is B: 12 inches
334.30 requires NM cable to be secured within 12 inches of every box, cabinet, or fitting, and supported at intervals not exceeding 4.5 feet elsewhere along the run. Leaving too much slack right at the box is a common rough-in defect an inspector will flag immediately.
Reference: NEC 2023 334.30 (Securing and Supporting — Type NM Cable)
Checked against multiple published sources
Three sources agree: a municipal code reproduction of 334.30 (Building, Fire and Related Codes 2024 edition), a 2023 NEC explainer, and a city 2020 NEC inspection checklist. The 12 in. and 4-1/2 ft figures are the same in 2020 and 2023. None is NFPA's own page.
Per Table 310.16, what is the allowable ampacity of a 6 AWG copper THWN conductor (75°C column), not more than three current-carrying conductors in a raceway?
Not quite. The answer is B: 65 A
6 AWG copper reads 55 A in the 60°C column, 65 A in the 75°C column, and 75 A in the 90°C column. THWN is a 75°C-rated insulation, so 65 A is the correct row/column intersection. Grabbing the 60°C or 90°C figure instead of matching the insulation's actual rating is the single most common lookup error on this table.
Reference: NEC 2023 Table 310.16 (Allowable Ampacity of Insulated Conductors)
Checked against multiple published sources
A Southwire spec sheet (ampacities stated as based on the 2023 NEC Table 310.16) and a Cerrowire ampacity chart agree on the 6 AWG copper values of 55/65/75 A. Neither is the code text.
Which of these dwelling-unit receptacle locations does NOT trigger the GFCI-protection requirement under 210.8(A)?
Not quite. The answer is D: A living room receptacle with no water source or outdoor exposure nearby
210.8(A) lists the dwelling-unit locations where receptacles need GFCI protection, among them bathrooms, garages, outdoors, crawl spaces, basements, kitchens, laundry areas and near sinks. An ordinary living room receptacle with no water source or outdoor exposure is not on that list, so it is the one that does not trigger the requirement. Exam-vs-field note: Washington's electrician exam is administered on the 2020 NEC, and every location offered in this question's other choices is already covered in 2020, so the answer holds for the exam. The 2023 NEC widened 210.8 further: basements of any kind (not only unfinished ones), all 125–250 V receptacles in kitchens rather than only those serving countertops, and outdoor outlets at garages, accessory buildings and boathouses. Study the 2020 list for the exam and know the longer 2023 list before you wire a house.
Reference: NEC 2023 210.8(A) (GFCI Protection for Personnel — Dwelling Units)
Checked against multiple published sources
A Mike Holt 2023 NEC changes text lists the dwelling-unit 210.8(A) locations (no living-room entry), and two state/city 2023 code-change documents confirm the 2023 kitchen change at 210.8(A)(6). None is the code text.
What is the minimum vertical clearance required for service-drop conductors over a residential driveway, measured at final grade?
Not quite. The answer is C: 12 feet
230.24(B) sets 12 feet as the minimum clearance for service-drop conductors over residential property and driveways for the common 120/208 V, 120/240 V and 277/480 V systems (the figure rises to 15 feet where the system exceeds 300 V to ground). Public streets, alleys, and commercial areas subject to truck traffic require the higher 18-foot clearance instead — confusing the residential and commercial clearance figures is a common exam trap.
Reference: NEC 2023 230.24(B) (Service Drop Clearances)
Checked against multiple published sources
A Mike Holt 2023 NEC series article and an ECM services article both give 12 ft over residential property and driveways in 230.24(B). The 2023 text frames this by system voltage (120/208, 120/240, 277/480 V) rather than the older 300 V-to-ground wording. Neither is the code text.
What multiplier does 625.41 require when sizing the branch circuit for electric vehicle supply equipment (EVSE)?
Not quite. The answer is D: 125% of the maximum load, since EV charging is treated as a continuous load
625.41 treats electric vehicle charging as a continuous load, requiring the branch circuit and its overcurrent protection to be sized at 125% of the EVSE's maximum load — the same continuous-load logic that governs lighting and other steady loads elsewhere in the code, just applied to a newer equipment type.
Reference: NEC 2023 625.41 (EVSE Branch-Circuit Sizing)
Checked against multiple published sources
A Mike Holt 2023 NEC changes text places the 125 percent EVSE overcurrent rule at 625.41; an ECM article groups it under 625.40-625.41 without naming an edition. Neither is the code text.
What is the minimum length of bare copper conductor (or rebar) required for a concrete-encased electrode ("Ufer ground") to qualify as a grounding electrode?
Not quite. The answer is D: 20 feet
250.52(A)(3) requires at least 20 feet of either 1/2-inch (or larger) rebar or bare copper conductor not smaller than 4 AWG, encased in at least 2 inches of concrete near the bottom of a foundation or footing in direct contact with the earth. Confusing this 20-foot minimum with the 8-foot ground-rod length is a common mix-up.
Reference: NEC 2023 250.52(A)(3) (Concrete-Encased Electrode)
Checked against multiple published sources
Two independent secondary sources agree on the requirement; neither is the code text. The ECM source is an older article that names no edition; the 20 ft, 1/2 in. rebar and 2 in. cover figures agree across both.
A motor's FLC is 40 A. Using an inverse-time circuit breaker at the maximum percentage generally permitted by Table 430.52(C)(1) for branch-circuit short-circuit and ground-fault protection (250%), what is the maximum standard breaker rating?
Not quite. The answer is C: 100 A
40 A × 250% = 100 A, which is itself a standard breaker size, so no rounding is needed here. This maximum percentage exists so the breaker can ride through a motor's brief high-inrush starting current without nuisance tripping, while still clearing an actual short circuit or ground fault — it is not sized to protect the motor from ordinary overload, which is the overload relay's job.
Reference: NEC 2023 Table 430.52(C)(1) (Maximum Rating — Inverse-Time Breaker)
Checked against multiple published sources
A Mike Holt motor chart (inverse-time breaker at 250% of FLC per Table 430.52(C)(1) and 240.6(A)) and an ECM article (examples at 250%, citing 430.52(C)(1) Ex 1; based on the 2011 NEC) agree. An ECM 2023 NEC article (read 2026-11-03) confirms the 2023 NEC names the table Table 430.52(C)(1) (formerly Table 430.52) with requirements unchanged from 2020. Neither is the code text.
True or False: Chapter 9, Table 1's 40% fill allowance applies to any raceway holding three or more conductors, regardless of conduit type (EMT, RMC, or PVC).
Not quite. The answer is B: True
The 40% cap for three-or-more conductors is a raceway-fill rule from Chapter 9, Table 1, and it applies uniformly across EMT, RMC, IMC, and PVC — the conduit material doesn't change the percentage, only its internal area (from Table 4) changes what that percentage translates to in square inches.
Reference: NEC 2023 Chapter 9, Table 1 (General Fill Percentages)
Checked against multiple published sources
Two independent secondary sources agree on the requirement; neither is the code text. One source is a 2016 article that names no edition; the other uses 2023 NEC values.
A 44 A continuous load terminates on equipment whose terminals are listed for 75°C only. What is the smallest copper conductor from Table 310.16 that can be used?
Not quite. The answer is B: 6 AWG
Minimum ampacity is 44 A × 1.25 = 55 A. Because the terminals are only rated 75°C, the conductor must be sized from the 75°C column even if its insulation is 90°C-rated (110.14(C)(1)). 8 AWG reads 55 A on the 90°C column but only 50 A on the 75°C column — short of the requirement. 6 AWG reads 65 A at 75°C, which clears it. Reading the higher 90°C figure instead of respecting the equipment's termination limit is the exact mistake this rule is designed to catch.
Reference: NEC 2023 110.14(C)(1) (Temperature Limitations — Equipment Terminal Ratings)
Checked against multiple published sources
Two independent secondary sources agree on the requirement; neither is the code text. Both sources were written against an earlier table number (310.15(B)(16)); the 110.14(C)(1) temperature rule is the same, and the ampacity table is Table 310.16 in the 2023 NEC.
Which of the following rooms is on the NEC's dwelling-unit AFCI branch-circuit protection list in the 2023 NEC (210.12(B))?
Not quite. The answer is B: Bedrooms
In the 2023 NEC the dwelling-unit list is in 210.12(B) (it was 210.12(A) in the 2020 NEC; in 2023 subdivision (A) now covers the permitted AFCI methods). It lists the habitable and living-type areas of a dwelling unit that need AFCI protection — kitchens, family, dining and living rooms, bedrooms, closets, hallways, laundry areas and similar spaces. Bathrooms, garages and unfinished basements are not on that list; they are covered by the separate GFCI list in 210.8(A), and some rooms (kitchens, laundry areas) need both. Exam-vs-field note: Washington's exam uses the 2020 NEC. We have found no 2020-to-2023 change that alters this answer, but confirm against your own codebook.
Reference: NEC 2023 210.12(B) (AFCI Protection — Dwelling Units)
Checked against multiple published sources
A Mike Holt 2023 NEC changes text and a St. Paul 2023 AFCI notice both place the dwelling-unit AFCI list in 210.12(B) in the 2023 NEC (it was 210.12(A) in the 2020 NEC) and both list bedrooms; bathrooms and garages are not on it. Neither is the code text.
Where must the service disconnecting means be installed relative to the point where service conductors enter the building?
Not quite. The answer is C: At a readily accessible location, either outside the building or nearest the point of entrance of the service conductors
230.70(A)(1) requires the service disconnect to sit at a readily accessible location, either outside the building or at the nearest point inside to where the service conductors enter — the goal is letting first responders and occupants kill power quickly, not burying the disconnect deep inside the structure.
Reference: NEC 2023 230.70(A)(1) (Service Disconnect Location)
Checked against multiple published sources
Two independent secondary sources agree on the requirement; neither is the code text. The ECM article is based on the 2011 NEC; the ExpertCE page cites the 2020 and 2023 editions without quoting them.
A Level 2 EVSE has a maximum continuous current of 80 A. Applying the 125% continuous-load factor from 625.41, what minimum branch-circuit rating is required?
Not quite. The answer is C: 100 A
80 A × 1.25 = 100 A minimum branch-circuit rating — this is exactly why an 80 A Level 2 EVSE is routinely paired with a 100 A dedicated circuit in the field. Sizing the circuit at the EVSE's nameplate current alone, without the continuous-load multiplier, would leave the installation undersized and out of compliance.
Reference: NEC 2023 625.41 (EVSE Branch-Circuit Sizing)
Checked against multiple published sources
A Mike Holt 2023 NEC changes text places the 125 percent EVSE overcurrent rule at 625.41 (its worked example is 40 A x 125% = 50 A); an ECM article groups it under 625.40-625.41 without naming an edition. Neither is the code text.
A single driven ground rod tests at 40 ohms resistance to earth. What does the NEC require?
Not quite. The answer is A: A second electrode must be installed and bonded to the first, since a single rod exceeding 25 ohms doesn't meet the exception that allows just one
250.53(A)(2) Exception allows a single rod, pipe, or plate electrode to stand alone only if it tests at 25 ohms or less; otherwise, a second electrode must be installed and bonded to the first, regardless of what the combined resistance measures out to afterward. At 40 ohms, this rod fails that exception and needs a supplemental electrode.
Reference: NEC 2023 250.53(A)(2) (Single Rod, Pipe, or Plate Electrode Exception)
Checked against multiple published sources
An ECM code quiz based on the 2023 NEC states the 25 ohm single-electrode exception at 250.53(A)(2), and an ExpertCE article describes the same rule at 250.53(A)(2). Neither is the code text.
A 25 kVA single-phase dry-type transformer has a 240 V primary. Applying 450.3(B)'s 125% maximum for primary-only protection (primary current ≥ 9 A), what is the required standard primary overcurrent device rating?
Not quite. The answer is C: 150 A
Primary FLC = 25,000 VA ÷ 240 V ≈ 104.17 A. At 125%, the calculated maximum is 104.17 × 1.25 ≈ 130.2 A — not a standard overcurrent device rating, so 450.3(B) permits rounding up to the next higher standard rating under 240.6(A), which is 150 A (there is no standard 130 A or 140 A size). Stopping at the raw 130.2 A calculation without taking the next step up is the trap.
Two trade-press articles agree that 450.3(B) Note 1 applies at primary currents of 9 A or more and allows the next higher standard rating under 240.6(A); the ECM example uses 125%. One is based on the 2020 NEC and the other names no edition. Neither is the code text.
A 1/2-inch EMT nipple under 24 inches long carries four 12 AWG THHN conductors. What is the fill percentage, and does it comply?
Not quite. The answer is B: 17.5% — complies with the 60% nipple fill limit
Four 12 AWG THHN conductors occupy 4 × 0.0133 = 0.0532 sq in inside a 1/2-inch EMT's 0.304 sq in total area, or 17.5% fill. Because this run is a nipple under 24 inches, Chapter 9's 60% nipple allowance applies instead of the usual 40% cap for three or more conductors — a distinction people miss when they default to the general fill table without checking run length.
Reference: NEC 2023 Chapter 9, Table 1, Note 4 (Conduit Nipple Fill Exception)
Checked against multiple published sources
Two independent secondary sources agree on the requirement; neither is the code text. The 24-inch nipple allowance is Note 4 to Chapter 9, Table 1. One source is an older article that names no edition.
A premises has branch circuits from both a 120/208 V system and a 277/480 V system. What does 210.5(C) require for the ungrounded conductors?
Not quite. The answer is B: Each ungrounded conductor must be identified by phase or line and by system at every termination, connection and splice point, using a documented method such as color coding, tape or tagging
The NEC does not mandate a color palette for ungrounded conductors. When a premises has branch circuits from more than one nominal voltage system, 210.5(C) instead requires each ungrounded conductor to be identified by phase or line and by system wherever it terminates, connects or splices, using any method (separate color coding, marking tape, tagging) that is documented. Brown/orange/yellow for 277/480 V and black/red/blue for 120/208 V is a widespread industry convention, not an NEC rule. The colors the NEC does fix are green or bare for equipment grounding (250.119) and orange or another effective marking for a delta high leg (110.15).
Reference: NEC 2023 210.5(C)(1) (Identification of Ungrounded Conductors — Multiple Voltage Systems)
Checked against multiple published sources
Two trade-press explanations agree on the requirement; neither is the code text. Sub-item lettering under 210.5(C)(1) differs by edition.
When conductors of a feeder are installed in parallel across multiple raceways, what is the smallest conductor size the NEC generally permits for that parallel arrangement?
Not quite. The answer is A: 1/0 AWG
310.10(G) sets 1/0 AWG copper or aluminum as the smallest conductor size generally permitted to be paralleled, and every parallel set must match in length, material, insulation, and termination method. Paralleling smaller conductors instead of stepping up to one larger conductor is a common design shortcut the code doesn't allow.
Reference: NEC 2023 310.10(G) (Conductors in Parallel)
Checked against multiple published sources
Two trade-press sources place paralleling at 310.10(G) in the 2023 NEC (it was 310.10(H) in 2020 and earlier). Neither is the code text.
What must a solar PV system's rapid shutdown function accomplish within the array boundary, and how fast?
Not quite. The answer is B: Reduce voltage within the array boundary to 80 V or less within 30 seconds of initiation
690.12 requires PV rapid shutdown to bring conductors within the array boundary down to 80 V or less within 30 seconds of activation, protecting firefighters and first responders working near or on a roof with live PV conductors. Getting the voltage and time figures reversed is an easy way to miss this question.
Reference: NEC 2023 690.12 (Solar PV Rapid Shutdown)
Checked against multiple published sources
An IAEI article on the 2023 NEC states 80 V within 30 seconds inside the array boundary under 690.12(B)(2); an ExpertCE article states the same limit and notes it carried through the 2020 and 2023 editions. Neither is the code text. The 2023 NEC also changed how the section is organized, so subsection letters differ from older editions.
Per Table 250.66, a service with 2 AWG copper (or smaller) ungrounded conductors requires a copper grounding electrode conductor (GEC) of at least what size?
Not quite. The answer is D: 8 AWG
Table 250.66 sets 8 AWG copper as the minimum grounding electrode conductor when the largest ungrounded service conductor is 2 AWG copper or smaller. The GEC grows with the service conductors, up to 3/0 AWG copper for the largest services. Separately, 250.66 limits the GEC to 6 AWG copper when its only connection is to a rod, pipe or plate electrode, and to 4 AWG copper when its only connection is to a concrete-encased electrode.
An NFPA fact sheet (2020 NEC, June 2020) reproduces the Table 250.66 row for 2 AWG copper or smaller (8 AWG copper) and the 6 AWG / 4 AWG caps in 250.66(A) and (B); an IAEI article agrees on the 8 AWG minimum and the caps. The fact sheet is NFPA's summary, not the code text, and is written against the 2020 edition.
Per 430.22, motor branch-circuit conductors for a single continuous-duty motor must generally be sized at not less than what percentage of the motor's full-load current?
Not quite. The answer is C: 125%
430.22 sets the baseline at 125% of the motor's full-load current (taken from the Article 430 tables) for the branch-circuit conductors of a single continuous-duty motor. This is a motor-specific rule that happens to match the 125% used for continuous loads elsewhere.
Reference: NEC 2023 430.22 (Motor Branch-Circuit Conductor Sizing)
Checked against multiple published sources
Three sources agree on 125% of full-load current: an ECM quiz based on the 2023 NEC, an ECM guide, and a Mike Holt motor chart citing 430.22. None is the code text.
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