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Special Occupancies & Equipment — Electrician Practice Questions

40 questions · 6% of the Electrician exam

Worked questions

1. Apply the 2023 NEC including issued TIA 23-17. A permanently installed swimming-pool pump motor is supplied by a 120-volt-to-ground, single-phase, 20-ampere branch circuit and does not qualify for the listed low-voltage exception. What ground-fault protection is required for the outlet supplying it, including a direct-wired connection?

  • AArc-fault protection alone at the panelboard
  • Class A GFCI protection
  • CA surge protective device instead of ground-fault protection
  • DAn isolated equipment grounding conductor instead of ground-fault protection

Where to look it up

https://docinfofiles.nfpa.org/files/AboutTheCodes/70/FD_D25_1_SC_25-4_6_d_TIA_1809_NFPA_70.pdf

Why B is correct

TIA 23-17 revises 680.21(C) to require ground-fault protection for outlets serving pool motors, subject to its stated low-voltage exception. For the specified 120 V-to-ground, 20 A single-phase circuit, 680.5(B) calls for a Class A GFCI. Direct wiring does not remove the outlet requirement. The amended rule should not be summarized as applying only to 15 A or 20 A pump circuits. Sources: issued TIA 23-17, effective April 30, 2025, PDF page 3: https://docinfofiles.nfpa.org/files/AboutTheCodes/70/FD_D25_1_SC_25-4_6_d_TIA_1809_NFPA_70.pdf; 2023 baseline 680.5(B), NFPA Public Input 4500, PDF page 364 (printed 117): https://docinfofiles.nfpa.org/files/AboutTheCodes/70/70_A2025_NEC_P17_FD_PIResponses.pdf

2. Under 2023 NEC 690.12, what is the safety purpose of the rapid shutdown function for a photovoltaic system on a building where that section applies?

  • APreventing utility backfeed during an outage
  • BProtecting modules against every lightning surge
  • CMatching solar production to low utility demand
  • Reducing the electric-shock hazard to firefighters

Where to look it up

https://docinfofiles.nfpa.org/files/AboutTheCodes/70/70_A2025_NEC_P04_FD_PIResponses.pdf

Why D is correct

The section identifies firefighter shock-hazard reduction as its purpose. It controls specified circuits and provides compliance alternatives; it does not declare the entire PV installation de-energized or safe to touch. In particular, inside-array compliance can use a listed or field-labeled PV hazard-control system, rather than a universal claim that every array conductor must be reduced to the same voltage. Source: 2023 baseline 690.12 and (B)(2), NFPA Public Input 4204, PDF pages 116–119 (printed 107–110). https://docinfofiles.nfpa.org/files/AboutTheCodes/70/70_A2025_NEC_P04_FD_PIResponses.pdf

3. A photovoltaic source circuit consists of one string of modules whose combined rated short-circuit current is 10 amperes. The Code sets the maximum circuit current at 125 percent of that rated short-circuit current, and then requires the circuit conductors to have an ampacity of at least 125 percent of the maximum circuit current before any temperature correction or conductor adjustment is applied. What minimum conductor ampacity results?

  • 15.6 amperes
  • B12.5 amperes

    This applies only the first 125 percent factor and stops. The conductor sizing step is a second, separate multiplication that this answer omits.

  • C10 amperes

    This uses the rated short-circuit current with no factors at all, which ignores both the sustained output of an array in bright cold conditions and the continuous duty allowance.

  • D19.5 amperes

    This applies the 125 percent factor three times. Only two multiplications are called for, one to establish maximum circuit current and one to size the conductor.

Why A is correct

The calculation stacks two separate 125 percent factors. The first converts rated short-circuit current into maximum circuit current, and the second sizes the conductor for continuous duty. Ten amperes becomes 12.5 amperes and then 15.6 amperes of required ampacity, all before temperature correction and conductor adjustment.

What this question is testing

This tests whether you apply both required factors, in the right order, and whether you know that the result is a pre-correction value rather than a final conductor selection.

On the job

On a real rooftop the correction that follows this calculation dominates. Conductors in conduit on a hot roof see ambient temperatures well above the table basis, and the correction factor can cut usable ampacity by a third or more, which is why photovoltaic feeders are routinely a size or two larger than the naive arithmetic suggests. Installers who size from the 15.6 ampere figure alone find their conductors undersized once the roof temperature adder is applied, and the correction is checked on every plan review.

Memory technique

One twenty-five for the sun, one twenty-five for continuous.

Exam tip

Photovoltaic circuits multiply by 125 percent twice for different reasons. Write both steps out so you do not stop after the first.

Where to look it up

Article 690 Part II, the circuit sizing and current sections. The temperature correction that follows comes from the ampacity tables and correction factors in Article 310.

4. A hospital room is designated a wet procedure location. For receptacles subject to 2023 NEC 517.20(A), which pair describes the permitted forms of special electric-shock protection?

  • AEquipment ground-fault protection set at 30 mA, or a panel directory label
  • BTwo grounding paths alone, or a warning sign
  • CArc-fault protection alone, or ordinary overcurrent protection alone
  • An isolated power system that limits first-fault current without interrupting supply, or a system that interrupts at the Class A GFCI trip level

Where to look it up

https://docinfofiles.nfpa.org/files/AboutTheCodes/70/70_A2025_NEC_P15_FD_PIResponses.pdf

Why D is correct

Section 517.20(A) provides these two protection alternatives. Ordinary equipment ground-fault or arc-fault protection is not a substitute for this specified protection. The separate exception for circuits supplying only qualifying listed fixed therapeutic and diagnostic equipment has its own conditions. The rule does not establish the original explanation’s blanket claim that every surgery requires isolated power. Source: unchanged 2023 baseline in NFPA Public Input 2100, PDF page 110 (printed 71). https://docinfofiles.nfpa.org/files/AboutTheCodes/70/70_A2025_NEC_P15_FD_PIResponses.pdf

5. Under 2023 NEC 555.33(A)(3), single receptacles on marina pedestals will supply shore power to boats. How must each receptacle be supplied?

  • From a marina power outlet or panelboard by an individual branch circuit whose voltage class and rating match the receptacle
  • BBy one shared 20-ampere branch circuit serving two boat slips
  • CBy one shared branch circuit serving all shore-power receptacles on the dock
  • DBy any shared general-purpose branch circuit if the receptacle is a locking type

Where to look it up

https://docinfofiles.nfpa.org/files/AboutTheCodes/70/70_A2025_NEC_P07_PISubmittals.pdf

Why A is correct

Section 555.33(A)(3) requires an individual branch circuit from a marina power outlet or panelboard for each single shore-power receptacle, with corresponding voltage class and rating. A locking connection does not replace that circuit requirement. Section 555.33(A)(4) separately requires shore-power single receptacles rated at least 30 amperes: 30- and 50-ampere receptacles are locking and grounding types, while receptacles rated 60 amperes or higher are pin-and-sleeve types. The individual-circuit rule does not by itself guarantee that upstream protection cannot disconnect other slips. Source: NFPA official Panel7 public-input submittals, PI1487, existing2023NEC555.33(A)(3)-(4), PDFpage311; the proposed change concerns the article title, as explained on PDFpage316. https://docinfofiles.nfpa.org/files/AboutTheCodes/70/70_A2025_NEC_P07_PISubmittals.pdf

35 more in the bank

Answers and explanations for these are in the app.

  • Under the NEC system for classifying hazardous locations, which hazard is the basis for designating an area as a Class II location?
  • In an area that contains a flammable vapor, what condition distinguishes a Division 2 location from a Division 1 location?
  • What is the primary function of a conduit seal installed in a raceway that leaves a Class I hazardous location?
  • Which wiring method is generally permitted for a power circuit installed in a Class I, Division 1 location?
  • What is the purpose of the equipotential bonding required around a permanently installed swimming pool?
  • How must the branch circuit supplying an underwater luminaire that operates above the low-voltage contact limit be protected?
  • What grounding arrangement does the Code require for branch circuits serving receptacles and fixed equipment in a patient care space?
  • What does an assured equipment grounding conductor program on a construction site require the responsible employer to do?
  • Why does the Code require an equipotential plane in the areas of agricultural buildings where livestock stand on concrete and contact metal equipment?
  • How must the branch circuit supplying the required sign outlet at a commercial occupancy accessible to pedestrians be rated and loaded?
  • Flammable gases and vapors are sorted into groups by their ignition properties, and each group drives the construction of the equipment permitted in it. Which gas defines the Class I group carrying the most demanding requirements?
  • The Code offers a zone system as an alternative to the division system for classifying areas containing flammable gases or vapors. In that system, which condition describes a Zone 1 location?
  • A junction box connects to the conduit run from the forming shell of a wet-niche luminaire and is being mounted on a pool deck. How high must that box be placed?
  • An equipotential bonding arrangement is being installed around a permanently installed outdoor pool. What conductor and what extent does the Code specify for the perimeter surface portion of that bonding?
  • A spa is installed at a hotel rather than at a one-family dwelling. What does the Code require for the emergency means that stops the recirculation and jet system motors?
  • An emergency system supplies the illumination required for the means of egress in a building. After the normal supply fails, how quickly must that illumination become available?
  • Feeders and branch circuits are being installed to supply shore power receptacles at a marina. What ground-fault protection and what public notice does the Code require?
  • A building space is designed and intended for the assembly of 100 or more persons. Which wiring method does the Code accept for the fixed wiring within that assembly space?
  • Temporary wiring is installed to supply decorative lighting and similar displays tied to a holiday. For how long does the Code permit that temporary installation to remain in service?
  • A retail tenant space requires one sign outlet supplied by an individual 20-ampere branch circuit. The sign that will be connected has a nameplate rating of 700 volt-amperes. The Code sets a minimum value that must be included in the load calculation for each required sign branch circuit. What load must be included for that circuit?
  • In an aircraft hangar where aircraft with fuel in their tanks are stored or serviced, how does the Code classify the area at the hangar floor?
  • Conductors supply an electric motor driven fire pump. How does the Code require those supply conductors and their overcurrent protection to be treated?
  • A hydromassage bathtub is being installed in a dwelling bathroom. What does the Code require for its circuit and its equipment?
  • Wiring for an emergency system is being installed in a commercial building. How must those circuits relate to the normal system wiring?
  • Utility service-drop conductors operating at 0 to 750 volts pass above a permanently installed outdoor swimming pool. What minimum clearance does the Code require above the maximum water level?
  • A rigid metal conduit run inside a Class I, Division 1 area enters an enclosure that houses contacts which arc in normal operation. Where does the Code require the sealing fitting in that run to be installed?
  • A power circuit is being installed in a Class II, Division 1 area of a grain handling plant, where combustible dust is in the air under normal operating conditions. Which wiring method does the Code generally permit for that circuit?
  • At a motor fuel dispensing facility, the table of classified locations makes the space within 20 feet horizontally of a dispenser enclosure, extending from grade up to 18 inches above grade, a Class I, Division 2 location. A junction box for the canopy lighting is to be mounted on a bollard 16 feet from the nearest dispenser at a height of 10 inches above grade. How must that location be treated?
  • A pump motor for a permanently installed swimming pool is to be connected with a flexible cord and an attachment plug so that the unit can be removed for servicing. What limits does the Code place on that cord?
  • A wet-niche luminaire is being installed in the wall of a permanently installed swimming pool. Absent a listing that specifically permits a shallower installation, how far below the normal water level must the top of the luminaire lens be?
  • Wiring is being installed in a livestock confinement building where dust, moisture and corrosive vapors from manure are present throughout. What does the Code require of the wiring methods and the boxes used in that area?
  • A temporary power panel on a construction site supplies 125-volt single-phase receptacles that the trades plug their tools into. Which of those receptacles must have ground-fault circuit-interrupter protection for personnel?
  • A legally required standby system is being installed to supply loads that the authority having jurisdiction has designated, such as smoke control and certain communication equipment. Within what time after the normal supply fails must that system deliver power to those loads?
  • Direct-current photovoltaic source and output circuits from a rooftop array must be routed through the interior of a building to reach an inverter in a mechanical room. What does the Code require of the wiring method for the portion of that run inside the building?
  • Receptacles rated 125 volts, single phase, 15 and 20 amperes are being installed in an elevator pit, on the elevator car top, and in the elevator machine room. What ground-fault protection does the Code require for those receptacles?

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