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General Requirements & Definitions — Electrician Practice Questions

46 questions · 10% of the Electrician exam

Worked questions

1. While studying a requirement, an apprentice finds an Informational Note printed directly beneath the rule. How does the Code treat that text?

  • AIt is a mandatory rule and carries exactly the same weight as the paragraph it follows
  • BIt applies only in jurisdictions that have formally adopted the informative annexes of the Code
  • CIt becomes an enforceable requirement once the equipment involved is listed by a testing laboratory
  • It is explanatory material, informational only, and is not enforceable as a requirement

Where to look it up

https://docinfofiles.nfpa.org/files/AboutTheCodes/70E/NEC_Style_Manual_2023_v2.pdf

Why D is correct

An Informational Note explains the associated rule; it does not itself add an enforceable NEC requirement. The NEC Style Manual distinguishes explanatory notes from mandatory provisions and does not permit notes to contain requirements or recommendations. A note may point to another provision or standard, whose applicability must be checked separately. Listing equipment does not change the note into a requirement. Source: https://docinfofiles.nfpa.org/files/AboutTheCodes/70E/NEC_Style_Manual_2023_v2.pdf

2. Under the 2023 NEC Article 100 definition, what makes a location on a wiring system an outlet?

  • It is a point where the wiring supplies current to equipment that uses electrical energy
  • BIt is exclusively the plug-contact hardware in a receptacle
  • CIt is any location containing a switch, whether or not equipment is supplied there
  • DIt is the energy-consuming equipment itself, rather than its supply point

Where to look it up

https://docinfofiles.nfpa.org/files/AboutTheCodes/70/70_A2025_NEC_P01_FD_PIResponses.pdf

Why A is correct

An outlet is the supply point on the wiring system, rather than the supplied equipment or exclusively a plug-in contact device. The definition is not limited to receptacle connections. Merely locating a switch at a point does not establish that current is taken there to supply utilization equipment. Source: 2023 baseline definition in NFPA Public Input 174, PDF page 90 (printed 85); the proposed replacement wording is not used. https://docinfofiles.nfpa.org/files/AboutTheCodes/70/70_A2025_NEC_P01_FD_PIResponses.pdf

3. An ordinary plumbing drain is proposed inside an indoor panelboard’s dedicated electrical space. Under 2023 NEC 110.26(E)(1)(a), which description identifies the space that must exclude that drain?

  • The equipment’s width and depth, from the floor to 6 feet above the equipment or the structural ceiling, whichever is lower
  • BOnly the first 3 feet above the enclosure, with a drip pan allowing piping inside that space
  • CThe equipment footprint to the structural ceiling regardless of height
  • DNo dedicated space is required for a surface-mounted panelboard rated 200 amperes or less

Where to look it up

https://docinfofiles.nfpa.org/files/AboutTheCodes/70/70_A2025_NEC_P01_FD_PIResponses.pdf

Why A is correct

The dedicated zone has the stated footprint and lower-of-two height limit; ordinary foreign piping cannot occupy it. Foreign systems above that zone have separate protection requirements under (b). A drip pan does not make an ordinary drain acceptable inside the zone. Source: unchanged 2023 baseline (a)/(b) in NFPA Public Input 246, PDF page 293 (printed 242). https://docinfofiles.nfpa.org/files/AboutTheCodes/70/70_A2025_NEC_P01_FD_PIResponses.pdf

4. Exposed live parts of a control assembly operating at 480 volts must be guarded against accidental contact. Which method satisfies that requirement?

  • ABrushing a coat of insulating paint over the exposed busbars and terminal connections

    Insulating paint is not a recognized guarding method and has never been an acceptable substitute for an enclosure, a barrier, elevation, or restricted access.

  • BPosting a warning sign on the door of the room in which the assembly is installed

    Warning signs at entrances are separately required where live parts are exposed, but a sign does not guard anything and cannot stand alone as the method.

  • CMounting the assembly so its live parts sit at least 4 ft above the finished floor

    Elevation is a permitted method only at 8 ft or more above the floor. Four feet leaves live parts squarely within reach of a passerby.

  • Locating the assembly in a room or vault accessible only to qualified persons

Why D is correct

Restricting the space to qualified persons is one of the listed guarding methods, and it works because the definition of a qualified person carries both skills and knowledge about the equipment and documented safety training to recognize and reduce the hazards. Anyone who enters that room is therefore assumed to understand what the exposed bus can do.

What this question is testing

This checks that you know guarding is a short closed list of methods rather than a general instruction to be careful. It also tests the 50 volt trigger and the 8 ft elevation figure, plus the role of a qualified person in making restricted access an acceptable method.

On the job

Industrial plants are full of this. Open control assemblies, exposed bus in a switchgear lineup, and older equipment with missing dead fronts all sit in areas where production staff walk. The usual fix is either restoring the enclosure or converting the corner into a restricted electrical room with a locked door and the required entrance signage. The 50 volt threshold catches things people assume are harmless, including many control circuits, and the elevation allowance is high enough that it is rarely the practical answer indoors.

Memory technique

Fifty volts starts it; enclose, restrict, screen, or raise it eight feet.

Exam tip

Remember two numbers here: guarding starts at 50 volts, and elevation only works at 8 ft or more.

Where to look it up

Article 110, the section on guarding of live parts, near the end of the general requirements. Qualified person is defined back in Article 100.

5. Under 2023 NEC 90.3, how do Chapters 5, 6 and 7 relate to the generally applicable chapters for the occupancies, equipment and conditions they cover?

  • AThey apply only if each chapter is separately selected by an inspector
  • BThey cannot change a general requirement
  • They can supplement or modify the general requirements within their applicable scope
  • DThey apply only to utility-owned installations

Where to look it up

https://docinfofiles.nfpa.org/files/AboutTheCodes/70/70_A2025_NEC_P01_FD_PIResponses.pdf

Why C is correct

Chapters 1–4 apply generally, while Chapters 5–7 address special applications and can supplement or modify requirements in Chapters 1–7. The 2023 text separately treats Chapter 8 through its specific references; informative annexes are not mandatory requirements. Source: 2023 baseline 90.3 and Figure 90.3 in NFPA Public Input 191, PDF page 37 (printed 33). https://docinfofiles.nfpa.org/files/AboutTheCodes/70/70_A2025_NEC_P01_FD_PIResponses.pdf

6. Under the 2023 NEC location definitions, a roofed open porch is protected from weather, experiences moderate moisture and is not subject to saturation. How is this location classified?

  • AWet
  • BDry
  • CHazardous (classified), solely because of moisture
  • Damp

Where to look it up

https://www.engproducts.com/product-resources/nec-references/luminaires-lamp-holders-and-lamps-nec-code

Why D is correct

These stated conditions fit the damp-location definition. A roof alone would not establish that classification if actual exposure differed. Moisture alone does not establish a hazardous classification. Source: https://www.engproducts.com/product-resources/nec-references/luminaires-lamp-holders-and-lamps-nec-code

7. A 75 kVA three-phase transformer steps 480 volts down to 208Y/120 volts and is marked with a nameplate impedance of 2.5 percent. Its primary full-load current is 90 amperes and its secondary full-load current is 208 amperes. Available fault current at the secondary terminals is approximated by dividing the secondary full-load current by the per-unit impedance. What is the approximate available fault current at those terminals?

  • AAbout 14,400 amperes

    This comes from computing the secondary current without the square root of three, treating a three-phase transformer as though it were single phase, then dividing by the impedance.

  • BAbout 3,600 amperes

    This divides the primary full-load current by the impedance. Fault current at the secondary terminals must be based on the secondary current.

  • About 8,300 amperes
  • DAbout 830 amperes

    This divides by 25 percent rather than 2.5 percent, a decimal slip that understates the fault current by a factor of ten and would justify badly underrated equipment.

Why C is correct

The approximation divides secondary full-load current by per-unit impedance: 208 amperes divided by 0.025 gives about 8,320 amperes. Lower nameplate impedance means a stiffer transformer and higher fault current, which is why a low-impedance unit can push equipment past its rating even on a modest kVA.

What this question is testing

This tests whether you can carry a two-step calculation and whether you keep primary and secondary quantities straight. The distractors are built from the three errors that actually occur: dropping the square root of three, using the wrong side of the transformer, and misplacing the decimal on the impedance.

On the job

This calculation is the first thing done when a panel or a control cabinet has to be matched to a service. Utilities publish available fault current at the service point, and a transformer inside the building sets it again for everything downstream. The number falls off quickly along a feeder, which is why a panel 200 feet away can use lower rated devices than one bolted to the transformer. When equipment cannot be rated high enough, the fix is a current-limiting device ahead of it, and that solution has to be engineered rather than guessed.

Memory technique

Full-load current divided by per-unit impedance gives the fault.

Exam tip

Write the impedance as a decimal before you divide. Most errors on this calculation are decimal errors, not conceptual ones.

Where to look it up

Article 110 Part I, the interrupting rating section and the field marking of available fault current a few sections later. The transformer data comes from the equipment nameplate rather than from a Code table.

8. A caution, warning or danger marking is required by the 2023 NEC. Under 110.21(B), which statement describes its field-applied hazard-marking requirements?

  • AAny fully handwritten label is sufficient if readable from 3 feet
  • It must communicate the hazard, withstand its environment and be permanently affixed; legible handwriting is allowed for variable portions
  • CEvery marking must be a riveted engraved-metal plate
  • DOnly factory-applied markings can satisfy the requirement

Where to look it up

https://docinfofiles.nfpa.org/files/AboutTheCodes/70/70_A2025_NEC_P01_FD_PIResponses.pdf

Why B is correct

The rule requires effective hazard communication, environmental durability and permanent attachment. Its handwriting exception applies to variable or changeable portions, which must be legible. It does not prescribe engraved metal for every case. Source: unchanged 2023 baseline in NFPA Public Input 3056, PDF page 243 (printed 195); the proposed general font-size addition is not used. https://docinfofiles.nfpa.org/files/AboutTheCodes/70/70_A2025_NEC_P01_FD_PIResponses.pdf

38 more in the bank

Answers and explanations for these are in the app.

  • Under the scope stated in Article 90, which of the following installations falls outside the rules covered by the National Electrical Code?
  • Article 90 assigns enforcement of the Code to an inspecting body. Which responsibility belongs to the authority having jurisdiction?
  • Article 100 draws careful lines between several terms describing product acceptance. Which description matches the Code term listed?
  • A junction box carries a small stamped mark from a testing agency on its side. Which Code term best describes a product bearing such a mark?
  • A Code rule requires a fitting to be identified for use in wet locations. What does that requirement actually place on the installer?
  • A disconnect is mounted above a suspended ceiling and reached with a portable ladder through a lift-out tile. How does the Code classify that equipment?
  • A contractor must decide whether a rented studio space above a garage meets the Code definition of a dwelling unit. What must that space contain?
  • A load calculation turns on whether the store lighting counts as a continuous load. What condition makes a load continuous under the Code?
  • Two electricians disagree about what an ampacity value in the conductor tables actually represents. Which statement defines ampacity correctly?
  • Instructions shipped with a listed panelboard call for a specific conductor arrangement that the Code text never mentions. How must the installer treat those instructions?
  • A 277/480-volt panelboard is installed on a wall, with a bare concrete block wall directly across the working space from its live parts. What minimum depth of clear working space is required?
  • A disconnect enclosure is marked with a tightening value in pound-inches for its line terminals. How must the electrician make up those terminations?
  • Equipment is being selected for a location where the available fault current is high. What does the Code require of the equipment short-circuit current rating, the circuit impedance, and the overcurrent devices ahead of that equipment?
  • A motor control center is installed in an industrial building and is likely to require examination, adjustment, servicing, or maintenance while energized. What marking does the Code require on that equipment?
  • A Code rule gives a conductor size but does not state the conductor material. How is that size to be applied, and how does the Code express conductor sizes generally?
  • Equipment is being mounted on a masonry wall and relies on the natural circulation of air across its surfaces to stay within its temperature rating. What does the Code require of that installation?
  • Equipment is going to be installed where it will be exposed to fumes and vapors that have a deteriorating effect on conductors and enclosures. What does the Code require?
  • A dispute arises over where the serving utility's facilities end and the premises wiring begins. Which description matches the Code term for that boundary?
  • A hotel accommodation consists of two contiguous rooms that together provide living, sleeping, sanitary, and storage facilities, with no permanent provisions for cooking. Which Code term describes that accommodation?
  • Conductors are installed in a raceway that is buried in a concrete slab, although the conductors themselves could later be withdrawn from that raceway. How does the Code classify those conductors?
  • A designer wants to use an arrangement the Code does not describe and reports that the inspector has agreed to allow it. What form must that agreement take before it qualifies as special permission?
  • A freestanding pole in a parking lot carries a sign and the wiring that supplies it. Which Code term applies to that pole, and what distinguishes a building from it?
  • A branch circuit is taken from one ungrounded conductor and the grounded conductor of a 208Y/120-volt system. Which statement describes what actually makes that grounded conductor a neutral conductor?
  • A room in a commercial building contains a sink together with permanent provisions for food preparation and cooking. Which Code term applies to that room?
  • A wiring installation has been completed and is about to be energized. What condition does the Code require of that completed installation?
  • Conductor insulation types are named by strings of letters, and each letter carries a meaning. In those type designations, what do the letters H and W indicate?
  • Two kinds of protection in the Code are commonly called ground-fault protection. Which statement correctly distinguishes them?
  • Overhead conductors run from a utility pole to a house. From the point of connection the premises conductors continue to the meter and then to the disconnect. Which term describes the conductors running from the service point to the service disconnecting means?
  • A 30-ampere branch circuit supplies a single piece of utilization equipment and serves no other outlet or load. What does the Code call that circuit?
  • Which description matches the Code definition of a panelboard?
  • Several disconnect switches are installed together in a mechanical room, each serving different equipment. What identification does the Code require?
  • A switchboard rated 1200 amperes and containing overcurrent devices is installed in an electrical room. A personnel door is located about 15 feet from the nearest edge of the required working space. What does the Code require of that door?
  • An enclosure is being selected for a disconnect switch mounted outdoors, where it will be exposed to falling rain, snow, and sleet. Which enclosure type does the Code table identify for that use?
  • Two conductors are to be terminated under a single terminal in a piece of equipment. What does the Code require?
  • A Code requirement states a dimension in both metric units and inch-pound units. How does the Code treat those two values?
  • A panelboard arrives on the job bearing the listing mark of a qualified electrical testing laboratory. What does the Code say about examining its internal construction?
  • Two 480-volt motor control centers face each other across an aisle. Exposed live parts are on both sides of the working space and neither side is guarded by insulating material. What minimum depth of clear working space is required?
  • Boxes of supplies are stacked on the floor in front of a panelboard, inside the space the Code requires to be kept clear. How does the Code treat that?

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