Hoja de Referencia del Examen · Referencia Rápida
North Carolina Unlimited Electrical Contractor (U)
North Carolina · PSI Services Contractor
Verificado, no estimado. Cada cifra a continuación proviene de la estructura oficial del examen que mantenemos: número de preguntas, puntaje de aprobación y ponderación de temas. Las preguntas de práctica están fundamentadas en la ley fuente con citas de estatutos. Omitimos cualquier cifra que no podamos verificar en lugar de adivinarla.
Total de preguntas
100
Puntaje de aprobación
70%
Tiempo del examen
360 min
Administrado por
PSI Services Contractor
Formato
Se permiten materiales de referencia
Porción Estatal de North Carolina 100 preguntas
Unión y Puesta a Tierra
11 Q · 11%
Systems and equipment requiring grounding and ground-fault protectionLocation of connection and required interconnectionsConductor identification and color codingBonding jumpersGrounding electrode conductorsEquipment grounding conductorsGrounding electrodesLow-voltage specificationsHigh-voltage specificationsBonding conductor connectionsBonding/bonding gridTermination
Protección contra Sobrecorriente
9 Q · 9%
Location in circuitSizing requirementsCircuit breakersPlug and cartridge fusesEnclosures and locationsHigh-voltage
Métodos de Cableado y Terminaciones
10 Q · 10%
Permitted applications and usagesCharacteristicsConduit and wireway fillPermitted applications and usagesCharacteristicsProtection from damageTraveling cables and controlsPermitted usages and ampacity ratingsCharacteristicsMiscellaneousOutdoorsSwitchboards, panelboards, switches, and cabinets
+2 más
Cajas y Accesorios
7 Q · 7%
General informationSizing requirements
Acometida y Equipos
9 Q · 9%
Installation requirementsService equipmentGeneral sizing requirements
Motores y Cableado de Control
9 Q · 9%
General informationBranch circuit and feeder ampacityOverload protectionShort-circuit and ground-fault protectionDisconnects/controllersSizeTypeLocationSeparation of conductors
Ocupaciones Especiales y Lugares Peligrosos
9 Q · 9%
Emergency systemsHealth care facilitiesMobile homes and mobile home parksPlaces of assembly, theaters, and similar locationsSwimming poolsUnderwater lighting fixturesGeneral requirementsAircraft hangarsBulk storage plantsFinishing processesGas stations and commercial garages
Cálculos de Carga
11 Q · 11%
Branch circuitsTotal computed loadConductor ampacity requirementsLow-voltageHigh-voltage
Electrodomésticos, Equipos e Iluminación
7 Q · 7%
Air conditionersResidential, commercial, and industrial equipmentLighting fixturesSpace heating equipment and boilersTransformersMachine room
General
3 Q · 3%
DefinitionsInstallation requirements
Leyes, Reglamentos, Prácticas Comerciales Básicas y Aplicaciones Prácticas
15 Q · 15%
Electrical Contractors Licensing Law (General Statutes Chapter 87, Article 4)Board’s Rules for the Implementation of the Electrical Contractors Licensing Law (Title 21, North Carolina Administrative Code, Chapter 18B)NASCLA Contractors’ Guide to Business, Law and Project Management - North Carolina Electrical EditionLighting and Power Plans; Estimating and General KnowledgeNational Fire Alarm Code
Distinciones Clave
NEC Full-Load Current Table (Table 430.250)vsMotor Nameplate Current
Table 430.250 values are used to size branch-circuit conductors and overcurrent protection, while the nameplate current is used only for sizing separate motor overload protection per 430.6(A)(2).
NEC, Section 430.6(A)(1)Straight Pull Box Length (314.28(A)(1))vsAngle Pull Box Distance (314.28(A)(2))
Straight pull minimum length = 8× the largest raceway trade size; angle pull minimum distance = 6× the largest raceway trade size plus the sum of all other raceway entries on the same wall.
NEC 314.28(A)(1)Nontime Delay Fuse (Motor Branch Circuit)vsDual Element (Time-Delay) Fuse (Motor Branch Circuit)
Per Table 430.52, nontime delay fuses are rated up to 300% of motor FLA, while dual-element time-delay fuses are rated up to 175% of motor FLA for AC polyphase motors.
NEC Table 430.52Motor Service Factor ≥1.15 Overload SettingvsStandard Motor Overload Setting
Motors with a service factor of 1.15 or greater may have overload protection set up to 125% of nameplate FLA; motors without this rating use a lower threshold per 430.32(A)(1).
NEC 430.32(A)(1)Supervised Industrial Installation Conductor Ampacity (240.91(B))vsStandard Conductor Ampacity Rule (240.4(C))
In supervised industrial installations with overcurrent devices rated over 800 A, conductors need only be rated at 95% of the device rating; outside Part VIII, conductors must equal or exceed 100% of the device rating.
NEC, Section 240.91(B)EMT Securing Distance from Termination (358.30(A))vsLFNC Securing Distance from Termination (356.30(1))
EMT must be secured within 900 mm (3 ft) of each termination, while LFNC must be secured within 300 mm (12 in.) of each outlet box, junction box, cabinet, or fitting.
NEC, Section 358.30(A)Grounded Circuit (250.21(A))vsCircuit Prohibited from Grounding (250.22)
Circuits listed in 250.21(A) are permitted but not required to be grounded, while circuits under 250.22 (e.g., crane circuits over combustible fibers in Class III locations) are expressly prohibited from being grounded.
NEC Handbook, Sections 250.22 and 250.21(A)SWD Marked Circuit BreakervsHID Marked Circuit Breaker
Per 240.83(D), both markings permit use as a switch, but SWD applies to 120V and 277V fluorescent lighting circuits, while HID applies to high-intensity discharge lighting circuits.
NEC 240.83(D)Type MC Cable in Plenum SpacevsType NM / ENT / PVC in Plenum Space
Per 300.22(C)(1), Type MC cable without an overall nonmetallic covering is permitted in plenum spaces without a metal raceway, while NM, ENT, and PVC are not permitted unless enclosed in an approved metal raceway.
NEC 2020, Section 300.22(C)(1)Edison-Base FuseholdervsType S Fuse Adapter
Per 240.52, Edison-base fuseholders shall only be installed where they are made to accept Type S fuses via adapters, preventing overfusing by restricting installed fuse ratings.
NEC 240.52Dead Front EquipmentvsExternally Operable Equipment
'Dead Front' means no live parts are exposed on the operating side, while 'Externally Operable' means the equipment can be operated without exposing the operator to contact with live parts at all.
NEC 2020, Article 100 (Definitions, Part I — Externally Operable)Feeder Disconnect for ≤2 Branch Circuits (225.39(B))vsFeeder Disconnect for One-Family Dwelling (225.39(C))
A structure supplied by not more than two 2-wire branch circuits requires a minimum 30-ampere disconnect, while a one-family dwelling requires a minimum 100-ampere, 3-wire disconnect.
NEC 225.39(B)Términos Clave
Continuous Load NEC 2020, Article 100 (Definitions, Part I — Continuous Load)
Per NEC Article 100, a load where the maximum current is expected to continue for 3 hours or more, critical for sizing conductors and overcurrent devices.
Externally Operable NEC 2020, Article 100 (Definitions, Part I — Externally Operable)
Per NEC Article 100, capable of being operated without exposing the operator to contact with live parts.
Arc Energy Reduction (240.87) NEC 240.87
Per NEC 240.87, arc energy reduction requirements apply when the highest continuous current trip setting of a circuit breaker is rated or adjustable to 1200 amperes or higher.
Main Bonding Jumper NEC 2020, Section 250.24(C)
Per NEC 250.24(C), the conductor that connects the grounded conductor(s) to each service disconnecting means enclosure in a grounded AC system operating at 1000 volts or less.
Grounding Electrode — Metal Underground Water Pipe (250.52(A)(1)) NEC, Section 250.52(A)(1)
Per NEC 250.52(A)(1), a metal underground water pipe qualifies as a grounding electrode only when it is in direct contact with the earth for 10 ft (3.0 m) or more.
Supplemental Electrode Exemption (250.53(A)(2)) NEC, Section 250.53(A)(2), Exception
Per NEC 250.53(A)(2) Exception, a supplemental grounding electrode is not required when a single rod, pipe, or plate electrode has a resistance to earth of 25 ohms or less.
Maximum Grounding Electrode Conductor to Rod/Pipe/Plate (250.66(A)) NEC, Section 250.66(A)
Per NEC 250.66(A), the grounding electrode conductor connected solely to a rod, pipe, or plate electrode need not be larger than 6 AWG copper or 4 AWG aluminum.
Conductor Termination Temperature Rating (110.14(C)(1)(b)) NEC 2020, Section 110.14(C)(1)(b)
Per NEC 110.14(C)(1)(b), for circuits over 100 amperes or conductors larger than 1 AWG, conductor ampacity at terminations must be based on the 75°C column unless the equipment is listed for higher ratings.
Parallel Conductor Minimum Size (310.10(G)(1)) NEC 2020, Section 310.10(G)(1)
Per NEC 310.10(G)(1), conductors connected in parallel for each phase, neutral, or grounded circuit shall not be smaller than 1/0 AWG.
High-Leg (Orange) Conductor Identification (110.15) NEC 2020, Section 110.15
Per NEC 110.15, on a 4-wire delta system with the midpoint of one phase winding grounded, the conductor with the higher phase voltage to ground shall be identified by an orange outer finish.
Free Conductor Length at Outlets (300.14) NEC 2020, Section 300.14
Per NEC 300.14, at least 150 mm (6 in.) of free conductor, measured from where it emerges from its raceway or cable sheath, shall be left at each outlet, junction, and switch point.
Box Fill — Device Yoke Allowance (314.16(B)(4)) NEC, Section 314.16(B)(4)
Per NEC 314.16(B)(4), each yoke or strap containing one or more devices requires a double volume allowance based on the largest conductor connected to a device supported by that yoke.
Paddle Fan Outlet Box Maximum Load (314.27(C)) NEC 314.27(C)
Per NEC 314.27(C), an outlet box used as the sole support of a ceiling-suspended paddle fan must be listed and marked for that purpose and shall not support fans weighing more than 32 kg (70 lb).
Series Rating Prohibition with Motor Circuits (240.86(C)) NEC 2020, Section 240.86(C)
Per NEC 240.86(C), series-rated combinations are not permitted where motor circuits are connected between the two devices and the sum of motor FLA exceeds 1% of the lower-rated breaker's interrupting rating.
Minimum Conductor Size — Up to 2000 Volts (310.3(A)) NEC 2020, Section 310.3(A)
Per NEC 310.3(A), the minimum conductor size for voltages up to and including 2000 volts is 14 AWG copper or 12 AWG aluminum or copper-clad aluminum.
Solder-Only Grounding Connection Prohibition (250.8(B)) NEC, Section 250.8(A) and (B)
Per NEC 250.8(B), connection devices or fittings that depend solely on solder shall not be used for grounding electrode conductors, equipment grounding conductors, or bonding jumpers.
Fórmulas que Debes Saber
Branch-Circuit Conductor Ampacity (Motor, NEC 430.6(A)(1))
Use NEC Table 430.250 FLA value (not nameplate) × 125% for continuous-duty motor branch-circuit conductor minimum ampacityMotor Branch-Circuit Fuse Size — Nontime Delay
Max fuse size = Motor FLA (from Table 430.250) × 300%Motor Branch-Circuit Fuse Size — Dual Element (Time-Delay)
Max fuse size = Motor FLA (from Table 430.250) × 175%; if result is not a standard size, round up to next standard size per 430.52(C)(1) Exception No. 1Motor Overload Protection (Service Factor ≥1.15)
Max overload trip = Nameplate FLA × 125%Supervised Industrial Conductor Ampacity (OCR > 800 A)
Min conductor ampacity = Overcurrent device rating × 95%Straight Pull Box Minimum Length
Min length = 8 × (trade size of largest raceway entering box)Angle Pull Box Minimum Distance
Min distance = (6 × largest raceway trade size) + (sum of all other raceway entry trade sizes on same wall)Dwelling Unit Load Calculation — Optional Method (NEC 220.83(A))
First 8 kVA of load × 100% + Remaining load × 40% (when no additional A/C or electric space heating is added)Box Fill — Volume per Conductor (12 AWG)
Each 12 AWG conductor = 2.25 in.³; each device yoke = double the volume of the largest conductor connected to itTotal Computed Load — Feeder Disconnect Minimum Rating
≤2 two-wire branch circuits → min 30 A disconnect; one-family dwelling → min 100 A, 3-wire disconnect; max 6 disconnects per supply grouping