Journeyman/Master Electrician License Exam Special Occupancies, Locations, and Systems Flashcards

24 sample cards from the Special Occupancies, Locations, and Systems deck

Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.

1. What is the maximum voltage for a wet-niche underwater pool luminaire, and what defines the 'low-voltage contact limit'?

   Pool luminaires must not exceed $150\text{ V}$ between conductors. The low-voltage contact limit is $30\text{ V}$ RMS / $42.4\text{ V}$ peak AC (or $60\text{ V}$ DC) for wet locations — luminaires at or below this and supplied by a listed transformer need not be GFCI-protected.

2. For a permanently installed spa or hot tub indoors, what receptacle and disconnect rules apply (Article 680)?

   At least one $125\text{ V}$ receptacle within $6\text{ ft}$ to $10\text{ ft}$ of the spa, GFCI-protected; a readily accessible disconnecting means must be located within sight and at least $5\text{ ft}$ from the spa/hot tub. Outlets supplying the spa must be GFCI-protected.

3. What is the disconnecting-means distance rule for a permanently installed pool, spa, or hot tub utilization equipment?

   A maintenance disconnecting means must be readily accessible, within sight of the equipment, and located at least $5\text{ ft}$ horizontally from the inside walls of the pool/spa/hot tub (unless separated by a permanent barrier).

4. For electric signs and outline lighting (Article 600), what is the required disconnecting means and where must it be located?

   Each sign and outline lighting system must have an externally operable disconnect that opens all ungrounded conductors, located within sight of the sign (or capable of being locked in the open position if out of sight) and within sight of the controller for the sign.

5. What is the minimum branch-circuit rating dedicated to each commercial occupancy sign outlet (Article 600)?

   Each commercial building/occupancy accessible to pedestrians must have at least one outlet for sign/outline lighting at each entrance, supplied by a branch circuit rated at least $20\text{ A}$ that supplies no other load.

6. For neon/skeleton tubing signs operating above 1000 V, what GFCI/ground-fault protection is required (Article 600)?

   Transformers and electronic power supplies for signs must be listed and provided with secondary-circuit ground-fault protection. Neon secondary conductors above $1000\text{ V}$ have specific spacing, support, and listed standoff requirements; the equipment must include integral ground-fault protection.

7. For elevators, dumbwaiters, and escalators (Article 620), what is required for the disconnecting means in the machine room?

   A single means (fused switch or circuit breaker) capable of being locked in the open position must disconnect all ungrounded main power-supply conductors for each elevator, located in the machine room/control space within sight of the controller; it cannot disconnect the car light, receptacle, or ventilation that must remain energized for emergency operation.

8. What separate circuits must be supplied to an elevator car independent of the main power feeder (Article 620)?

   Separate branch circuits must supply the car lighting, receptacles, ventilation, and air-conditioning, and another for the machine room/hoistway lighting and receptacle — each with its own disconnect so power can be killed to the drive without de-energizing safety/lighting circuits.

9. What is Article 645 'Information Technology Equipment' and what condition allows its special (relaxed) wiring provisions to apply?

   Article 645 covers IT equipment and systems in an information technology equipment (IT) room. Its alternative wiring/cabling provisions apply only if the room meets all conditions: a disconnecting means for all IT equipment and HVAC, a dedicated HVAC system, listed IT equipment, occupancy by only those needed to maintain it, and separation by fire-resistant walls/floors/ceilings.

10. What disconnecting means is required for an information technology equipment room under Article 645?

    A means to disconnect power to all electronic IT equipment and to disconnect the dedicated HVAC serving the room, controlled from approved locations readily accessible at the principal exit doors. (Often combined with an Emergency Power Off / EPO, though recent NEC editions allow omitting EPO under certain listed conditions.)

11. In an IT equipment room, where may power cables, interconnecting cables, and receptacles be installed that would not be permitted elsewhere?

    Under the raised (access) floor, provided the floor is of suitable construction, ventilation/HVAC is dedicated, openings minimize air loss, and cables are listed or installed in metal raceway/approved cable types for under-floor use (NEC 645.5).

12. Distinguish a Legally Required Standby System (Article 701) from an Emergency System (Article 700).

    Emergency systems (700) supply power essential to life safety (egress lighting, exit signs, alarms) and are legally required for human safety, with power restored within $10\text{ s}$. Legally required standby systems (701) supply loads that, if lost, could create hazards or hamper rescue/firefighting (e.g., ventilation, communications), with power restored within $60\text{ s}$.

13. What is an Optional Standby System (Article 702) and how does it differ from emergency/legally-required standby?

    Optional standby systems protect against loss of power where life safety is not at stake — e.g., data processing, heating/refrigeration, industrial processes — to prevent economic loss or discomfort. They are installed at the owner's option and are not mandated by code for safety, with no maximum transfer time.

14. What maximum transfer time defines an Emergency System (700) versus a Legally Required Standby System (701)?

    Emergency System: power available within $10\text{ s}$. Legally Required Standby System: power available within $60\text{ s}$.

15. How must emergency system wiring (Article 700) be kept relative to normal wiring, and why?

    Emergency circuit wiring must be kept entirely independent of all other wiring and equipment (separate raceways, boxes, and cabinets), so a fault or fire in the normal system cannot disable the emergency system. Limited exceptions allow common enclosures only at transfer equipment, in listed luminaires, or in junction boxes attached to emergency luminaires.

16. In a solar PV system (Article 690), what is the maximum system voltage formula correction for crystalline-silicon modules using temperature coefficients?

    Maximum PV source/output voltage is the rated open-circuit voltage $V_{OC}$ corrected for the lowest expected ambient temperature: $V_{max} = V_{OC} \times (\text{number of series modules}) \times C_{temp}$, where $C_{temp}$ is the correction factor from NEC Table 690.7 (or computed from the module's temperature coefficient of voltage).

17. For sizing PV circuit conductors and overcurrent devices, by what factor must the PV source/output circuit short-circuit current ($I_{SC}$) be multiplied (Article 690)?

    The maximum continuous current is $1.25 \times I_{SC}$, and the conductor/OCPD must then be sized for continuous duty at $1.25$ times that value, giving an overall factor of $1.25 \times 1.25 = 1.56 \times I_{SC}$ before any temperature/conduit-fill derating.

18. What is 'rapid shutdown' in a PV system (NEC 690.12) and what does it limit?

    Rapid shutdown reduces the voltage of PV conductors to a safe level for firefighters: conductors more than $1\text{ ft}$ outside the array boundary must be reduced to $\leq 30\text{ V}$ within $30\text{ s}$ of initiation, and conductors inside the array boundary limited to $\leq 80\text{ V}$ within $30\text{ s}$ (module-level shutdown).

19. What is the function of a PV system disconnecting means and how many disconnects may be grouped (Article 690)?

    A readily accessible PV system disconnecting means must disconnect the PV system from all wiring systems including conductors of other systems; the disconnect must be marked and grouped, with no more than $6$ switches or breakers to disconnect the PV output (the 'six disconnect' rule).

20. What does Article 706 cover, and what is an Energy Storage System (ESS) as defined there?

    Article 706 covers permanently installed Energy Storage Systems (ESS) operating at over $50\text{ V}$ AC or $60\text{ V}$ DC — systems (e.g., battery, flow battery, capacitor) that store energy and provide electrical power, including their disconnects, controls, and overcurrent protection.

21. What disconnecting means and labeling are required for an Energy Storage System under Article 706?

    A readily accessible disconnecting means must disconnect the ESS from all conductors of other systems, located within sight of the ESS (or lockable if remote), and the system must be marked with maximum voltage, polarity of DC, available fault current, and short-circuit current rating at the disconnect.

22. Under Article 625 (Electric Vehicle Charging), what are the three EVSE charging levels by typical supply?

    Level 1 = $120\text{ V}$ AC, ~$12\text{–}16\text{ A}$ (standard receptacle). Level 2 = $208/240\text{ V}$ AC, up to ~$80\text{ A}$. DC Fast Charge (Level 3) = DC supplied directly to the battery at high power (e.g., $400\text{–}1000\text{ V}$ DC).

23. How must an EV charging branch circuit be sized and what duty classification applies (Article 625)?

    EVSE is a continuous load, so the branch circuit and overcurrent device must be rated at not less than $125\%$ of the EVSE's maximum load: $I_{circuit} \geq 1.25 \times I_{EVSE}$. The disconnecting means for EVSE rated over $60\text{ A}$ or over $150\text{ V}$ to ground must be readily accessible and lockable in the open position.

24. What ventilation consideration applies to indoor EV charging under Article 625?

    EVSE listed and marked as suitable for charging without ventilation may be installed indoors without mechanical ventilation; otherwise, mechanical ventilation must be provided, with airflow calculated based on the charging voltage and current per NEC Table 625.52 to dilute any hydrogen off-gassing.

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Special Occupancies, Locations, and Systems flashcards FAQ