Exam Cheat Sheet · Quick Reference
Oklahoma Unlimited Electrical Contractor
Oklahoma · PSI Services Contractor
Verified, not estimated. Every figure below is drawn from the official exam structure we maintain — question counts, passing standard and topic weighting. Practice questions are grounded in the source law with statute citations. We omit any figure we can't verify rather than guess at it.
Total questions
100
Passing score
70%
Exam time
240 min
Administered by
PSI Services Contractor
Format
Reference materials allowed
Oklahoma State Portion 100 questions
General Knowledge
4 Q · 4%
Purpose and scope of the NEC (practical safeguarding of persons and property)Installations covered and not covered by the NECNEC code arrangement and chapter organizationMandatory vs. permissive vs. explanatory rules (shall/shall not vs. shall be permitted)Authority having jurisdiction (AHJ) enforcement powers and special permissionExamination and listing of equipment for safetyWiring planning for future expansion and limiting circuits in enclosuresUnits of measurement (SI and inch-pound dual system, hard vs. soft conversion)
General Electrical Knowledge
10 Q · 10%
Ohm's Law formulas and calculations (voltage, current, resistance, power)Series, parallel, and combination circuit analysisAC electrical formulas for single-phase and three-phase systems (kW, kVA, HP, amperes)Voltage drop calculations for single-phase and three-phase circuitsGrounded conductor identification and use (NEC Article 200)NEC Article 300 general wiring methods and materials requirementsPower factor, impedance, reactance, and capacitance in AC circuitsCommon electrical distribution systems and conductor color coding
Electrical Installation Requirements
10 Q · 10%
Branch-circuit ratings, conductor sizing, and overcurrent protection requirementsGFCI and AFCI protection requirements by location and occupancy typeDwelling unit and non-dwelling receptacle and lighting outlet placement requirementsBranch-circuit and feeder load calculations including demand factorsVoltage drop calculations for single-phase and three-phase circuitsAmpacity correction and adjustment factors for ambient temperature and conductor fillUnderground installation minimum cover requirements and wiring method selectionGeneral wiring methods: physical protection, conductor support, raceway installation, and working space clearances
Services, Feeders, and Branch Circuits
10 Q · 10%
Branch-circuit ratings, conductor sizing, and overcurrent protection (Articles 210, 215, 230)Load calculations for branch circuits, feeders, and services using demand factors (Article 220)GFCI and AFCI protection requirements by location and occupancy typeService entrance requirements: number of services, disconnecting means, and overcurrent protectionConductor ampacity correction and adjustment factors for temperature and conduit fillVoltage drop calculations for single-phase and three-phase circuitsOverhead and underground service conductor clearances, wiring methods, and installation requirementsMotor branch circuit and feeder conductor sizing and overcurrent protection
Overcurrent Protection
9 Q · 9%
Standard ampere ratings for fuses and inverse time circuit breakers (Table 240.6(A))Conductor overcurrent protection requirements by wire size and material (240.4(D))Feeder tap rules and maximum tap conductor lengths (240.21(B))Motor branch-circuit overcurrent device maximum ratings by motor type (NEC Table 430.52)Motor overload protection placement and running overload unit requirementsArc energy reduction requirements for high-ampere overcurrent devices (240.67, 240.87)Short-circuit current calculation procedure including transformer let-through currentOvercurrent protection for systems over 1000 volts — circuit breaker and power fuse requirements (Article 245)
Grounding and Bonding
10 Q · 10%
Grounding electrode system types and installation requirements (NEC 250.52–250.54)Grounding electrode conductor sizing and installation (NEC Table 250.66)Equipment grounding conductor types, sizing, and identification (NEC 250.118–250.122)Main bonding jumper and system bonding jumper requirements and sizing (NEC Table 250.102(C)(1))Bonding of services, piping systems, and structural metal (NEC 250.92–250.104)Grounding of separately derived systems and generators (NEC 250.30, 250.34, 250.35)Permitted connection methods for grounding and bonding conductors (NEC 250.8, 250.70)Surge-protective device (SPD) and surge arrester grounding connection requirements (NEC Article 242)
Conductors and Cables
8 Q · 8%
Conductor insulation types, temperature ratings, and application provisions (NEC Article 310 Table 310.4)Ampacity tables for conductors in raceways, cables, and free air (Tables 310.16–310.21)Ampacity correction factors for ambient temperature and adjustment factors for more than three current-carrying conductorsConductor sizing, material, and stranding requirements (minimum sizes, copper vs. aluminum, AA-8000 series)Cable type uses permitted and uses not permitted (NM, NMC, MC, AC, SE, USE, UF, MI, TC, ITC, MV, and specialty types)Securing, supporting, and bending radius requirements for specific cable typesConduit fill calculations and maximum number of conductors in various raceway typesMedium voltage (Type MV) cable construction, shielding, insulation levels, and ampacity
Raceways and Boxes
10 Q · 10%
Conduit and tubing types: permitted uses, restrictions, and installation requirements (RMC, IMC, EMT, FMC, LFMC, FMT, PVC, RTRC, HDPE, LFNC, ENT, NUCC)Box fill calculations: conductor, clamp, device, fitting, and equipment grounding conductor volume allowancesPull and junction box sizing: straight pull and angle/U-pull minimum dimension requirementsSecuring and supporting requirements for raceways, conduit, and tubing (support intervals and fastening distances)Box and enclosure selection and installation: types, damp/wet location requirements, flush mounting, and accessibilityCable tray systems: types, permitted wiring methods, fill calculations, ampacity, grounding, and bondingWireways, auxiliary gutters, busways, and specialty raceway systems: uses permitted, conductor fill limits, and support requirementsGrounding and bonding of metallic raceways, boxes, and enclosures
Special Occupancies and Equipment
7 Q · 7%
Hazardous location classification — Class I, II, and III, Divisions 1 and 2Zone classification system — Zone 0, 1, 2, 20, 21, and 22 locationsWiring methods and sealing requirements in hazardous locationsHealth care facility essential electrical systems and patient care space wiringMotor fuel dispensing, commercial garages, aircraft hangars, and bulk storage plant electrical requirementsElevators, cranes, hoists, and electric vehicle power transfer systemsMobile homes, recreational vehicles, marinas, and temporary installationsTheaters, assembly occupancies, and entertainment venue wiring requirements
Low Voltage, Alarms, Signaling Systems, and Communications
6 Q · 6%
Fire alarm circuit types: NPLFA vs. PLFA power sources, branch circuit requirements, and overcurrent protectionFire alarm cable types, ratings, and application requirements (FPLP, FPLR, FPL, NPLFP, NPLFR, NPLF) including plenum, riser, and general-purpose installationsCircuit integrity (CI) cables and fire-resistive cable systems for survivability of critical circuitsClass 2 and Class 3 power-limited circuit wiring methods, power source requirements, and separation from other circuitsClass 1 power-limited remote-control and signaling circuit requirements, overcurrent protection, and conductor sizingCommunications system grounding, bonding, and primary protector requirements (Articles 800, 805, 820, 830)Cable types and installation methods for communications, CATV coaxial, optical fiber, and broadband systems including plenum/riser/general-purpose ratings and substitution hierarchiesClass 4 fault-managed power systems: transmitter/receiver requirements, fault management, separation rules, and cable types
Lighting and Signs
4 Q · 4%
Luminaire location requirements (wet, damp, corrosive, bathtub/shower zones, clothes closets)Recessed luminaire installation (Type IC vs. non-IC, thermal protection, clearances from insulation and combustible material)Lighting track installation requirements, permitted/prohibited locations, and construction standardsLuminaire support methods and grounding requirementsDisconnecting means for fluorescent and LED luminaires with double-ended lampsElectric sign and outline lighting branch circuit requirements, ratings, and disconnecting meansGrounding, bonding, and enclosure requirements for electric signs and outline lighting systemsNeon secondary-circuit wiring methods (1000 volts or less and over 1000 volts)
Safety
10 Q · 10%
Electrical hazard recognition and shock protection boundaries (limited and restricted approach)Lockout/tagout procedures and establishing an electrically safe work conditionArc-flash hazard analysis, equipment labeling, and PPE categoriesPersonal protective equipment selection, use, and employer payment requirementsGround-fault circuit interrupter (GFCI) and assured equipment grounding conductor programFire protection and prevention on construction sites (extinguisher ratings, flammable liquid storage, fire prevention plans)Confined space entry procedures, atmospheric testing, and permit requirementsOccupational health controls (noise exposure limits, airborne contaminant PELs, ventilation, asbestos handling)
Motors and Transformers
2 Q · 2%
Motor branch-circuit conductor sizing (125% rule, NEC Article 430 Part II)Motor branch-circuit short-circuit and ground-fault protection ratings and settings (Table 430.52)Motor overload protection requirements and trip current percentages (NEC 430.32)Motor disconnecting means types, ratings, and location requirements (NEC 430.109–430.112)Motor controller ratings, marking, and application requirements (NEC 430.83)Transformer overcurrent protection sizing for primary and secondary (NEC 450.3, Tables 450.3(A) and 450.3(B))Transformer sizing calculations and full-load current determination (single-phase and three-phase)Locked-rotor code letters and locked-rotor current calculations (Table 430.7(B), Tables 430.251(A) and 430.251(B))Delta and wye transformer connections (line vs phase voltage and current, neutral current, balancing)
Key Distinctions
Series Circuit (Resistance)vsParallel Circuit (Resistance)
In a series circuit, total resistance equals the sum of all individual resistances (RT = R1+R2+R3), whereas in a parallel circuit, total resistance is always less than the resistance of any individual branch.
Ugly's Electrical References, Series Circuits, Book Page 3Series Circuit (Current)vsParallel Circuit (Current)
In a series circuit, current is equal throughout every part of the circuit (IT = I1 = I2 = I3), whereas in a parallel circuit, total current equals the sum of all individual branch currents.
Ugly's Electrical References, Page 3NEC Chapters 1–4vsNEC Chapter 9
Chapters 1–4 apply generally to all electrical installations, while Chapter 9 consists of tables that are applicable only when specifically referenced by other code sections.
NEC, Section 90.3Three-Phase KW FormulavsThree-Phase Amperes Formula
KW = (E × I × PF × 1.73) / 1000 solves for power when current is known, while I = (KW × 1000) / (E × PF × 1.73) solves for current when power is known; both use the √3 factor of 1.73.
Ugly's Electrical References, Book Page 22Crane Contact ConductorsvsGeneral Feeders
Per NEC 610.21(H), crane contact conductors shall NOT be used as feeders for any equipment other than the crane(s) or hoist(s) they are primarily designed to serve, unlike general feeders which can serve multiple loads.
NEC Article 610.21(H)Crane Power Supply Conductor Ampacity (Largest Motor)vsCrane Power Supply Conductor Ampacity (Next Largest Motor)
Per NEC 610.14(E)(2), 100% of the largest motor's FLA is used, while only 50% of the next largest motor's FLA is added to determine minimum conductor ampacity.
NEC Article 610.14(E)(2)Elevator Supply Voltage Limit (General)vsElevator Supply Voltage Limit (Exceptions)
NEC 620.3 sets the general maximum at 300 volts between conductors, but higher voltages are permitted for specific power, lighting, and heating/air-conditioning circuits under 620.3(A)–(C).
NEC Article 620.3Temporary Wiring — Holiday Lighting (Permitted Duration)vsTemporary Wiring — Assured Grounding Program Test Interval
Holiday decorative temporary wiring is permitted for up to 90 days per NEC 590.3(B), while cord sets and receptacles under the assured equipment grounding conductor program must be tested at intervals not exceeding 3 months per NEC 590.6(B)(2).
NEC Article 590.3(B)Elevator Feeder Demand Factor (5 Elevators)vsElevator Feeder Demand Factor (10+ Elevators)
Per NEC Table 620.14, 5 elevators on a single feeder use a demand factor of 0.82, while 10 or more elevators use the minimum demand factor of 0.72.
NEC Table 620.14Crane Working Space (NEC 610.57)vsElevator Supply Voltage (NEC 620.3)
NEC 610.57 governs physical clearance (minimum 750 mm / 2½ ft) for crane live parts access, while NEC 620.3 governs the electrical parameter of maximum supply voltage (300 V) for elevator systems.
NEC Article 610.57Three-Phase HP-to-Amperes FormulavsThree-Phase KW-to-Amperes Formula
When horsepower is known, I = (HP × 746) / (E × %EFF × PF × 1.73); when kilowatts are known, I = (KW × 1000) / (E × PF × 1.73) — the HP formula also requires efficiency (%EFF).
Ugly's Electrical References, Pages 15-18Temporary Wiring ReceptaclesvsStandard Receptacles
Per NEC 590.4(D)(1), temporary installations require grounding-type receptacles with a separate equipment grounding conductor on all branch circuits, which is a stricter requirement than may apply to permanent installations.
NEC Article 590.4(D)(1)Key Terms
NEC Chapter 9 — Tables Applicability NEC, Section 90.3
Per NEC 90.3, Chapter 9 consists of tables applicable only as specifically referenced by other code sections, unlike Chapters 1–4 which apply generally.
Temporary Wiring — Holiday Lighting Duration (NEC 590.3(B)) NEC Article 590.3(B)
Per NEC 590.3(B), temporary electric power and lighting for holiday decorative purposes is permitted for a maximum of 90 days.
Temporary Wiring Receptacle Requirement (NEC 590.4(D)(1)) NEC Article 590.4(D)(1)
Per NEC 590.4(D)(1), all receptacles used in temporary installations must be of the grounding type, with branch circuits including a separate equipment grounding conductor.
Assured Equipment Grounding Test Interval (NEC 590.6(B)(2)) NEC Article 590.6(B)(2)
Per NEC 590.6(B)(2), cord sets and receptacles under the assured equipment grounding conductor program must be tested at intervals not exceeding 3 months.
Crane Contact Conductor Restriction (NEC 610.21(H)) NEC Article 610.21(H)
Per NEC 610.21(H), crane contact conductors shall not be used as feeders for any equipment other than the crane(s) or hoist(s) they are primarily designed to serve.
Crane Conductor Minimum Size (NEC 610.14(C)) NEC Article 610.14(C)
Per NEC 610.14(C), conductors external to crane motors and controls shall be not smaller than 16 AWG, with exceptions for control circuits (18 AWG ≤7A) and electronic circuits (20 AWG).
Crane Working Space Clearance (NEC 610.57) NEC Article 610.57
Per NEC 610.57, the working space in the direction of access to energized live parts on a crane that may require examination or servicing shall be a minimum of 750 mm (2½ ft).
Elevator Supply Voltage Limit (NEC 620.3) NEC Article 620.3
Per NEC 620.3, supply voltage for elevators, dumbwaiters, escalators, and moving walks shall not exceed 300 volts between conductors unless specific exceptions apply.
Elevator Feeder Demand Factors (NEC Table 620.14) NEC Table 620.14
Per NEC Table 620.14, demand factors for elevator feeders range from 1.00 (1 elevator) down to 0.72 (10 or more elevators), based on a 50% duty cycle assumption.
Crane Multi-Motor Conductor Ampacity (NEC 610.14(E)(2)) NEC Article 610.14(E)(2)
Per NEC 610.14(E)(2), minimum power supply conductor ampacity for a crane with multiple motors equals 100% of the largest motor's FLA plus 50% of the next largest motor's FLA.
Three-Phase Multiplier (√3 = 1.73) Ugly's Electrical References, Book Page 15
The factor 1.73 (approximate square root of 3) is used in all three-phase electrical formulas to account for the 120-degree phase relationship between conductors.
Ohm's Law — Resistance Ugly's Electrical References, Book Pages 1-2
Resistance R = E / I (voltage divided by current), or equivalently R = E² / P; used to find resistance when voltage and power or current are known.
Power Formula (Watts) Ugly's Electrical References, Pages 1-2
P = E × I (volts × amperes); for example, 120 V × 10 A = 1200 W.
Operating Cost Formula Ugly's Electrical References, Book Page 117
Monthly cost = (Watts × Hours Used × Rate per kWh) / 1000; e.g., a 5 kW heater running 12 hr/day for 30 days at $0.15/kWh costs $270/month.
Series Circuit Total Resistance Ugly's Electrical References, Series Circuits, Book Page 3
In a series circuit, RT = R1 + R2 + R3 (sum of all individual resistances), and current is the same throughout every element.
Parallel Circuit Total Resistance Ugly's Electrical References, Parallel Circuits, Book Page 5
In a parallel circuit, total resistance is always less than the smallest individual branch resistance, and total current equals the sum of all branch currents.
Formulas to Know
Series Circuit Total Resistance
RT = R1 + R2 + R3 + ...Parallel Circuit — Total Current
IT = I1 + I2 + I3 + ...Ohm's Law — Current
I = E / ROhm's Law — Resistance
R = E / I (or R = E² / P)Power (Watts)
P = E × IThree-Phase Kilowatts
KW = (E × I × PF × 1.73) / 1000Three-Phase Amperes (from KW)
I = (KW × 1000) / (E × PF × 1.73)Three-Phase Amperes (from HP)
I = (HP × 746) / (E × %EFF × PF × 1.73)Crane Multi-Motor Conductor Ampacity (NEC 610.14(E)(2))
Min. Ampacity = 100% × (Largest Motor FLA) + 50% × (Next Largest Motor FLA)Electrical Operating Cost
Cost ($) = (Watts × Hours × Rate per kWh) / 1000