Exam Cheat Sheet · Quick Reference
Oklahoma Residential 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
80
Passing score
70%
Exam time
210 min
Administered by
PSI Services Contractor
Format
Reference materials allowed
Oklahoma State Portion 80 questions
General Knowledge
4 Q · 5%
NEC purpose, scope, and installations covered vs. not coveredNEC code arrangement and chapter organizationMandatory, permissive, and explanatory rule languageAuthority having jurisdiction (AHJ) enforcement and special permissionUnits of measurement: SI metric and inch-pound dual system in the NECField trade terms versus official NEC terminologyElectrical symbols used in drawings and diagramsU.S. and metric unit conversions and equivalents
General Electrical Knowledge
12 Q · 15%
Ohm's Law formulas and calculations (voltage, current, resistance, power)Series, parallel, and combination circuit analysisVoltage drop calculations for single-phase and three-phase circuitsElectrical formulas for amperes, kilowatts, kVA, and horsepower (single-phase and three-phase)Grounded conductor identification, use, and terminal marking (NEC Article 200)General wiring methods requirements: conductor installation, protection, and raceway rules (NEC Article 300)Transformer calculations: sizing, primary/secondary amperes, and connectionsSwitches, receptacles, panelboards, and switchboards: ratings, installation, and grounding requirements
Electrical Installation Requirements
10 Q · 12%
Branch-circuit ratings, conductor sizing, and overcurrent protection requirementsGFCI protection requirements by location and occupancy typeAFCI protection requirements for dwelling units and other occupanciesDwelling unit receptacle outlet placement and spacing requirementsRequired lighting outlets and switching in dwelling units and all occupanciesUnderground installation minimum cover requirements by wiring methodConduit and raceway support spacing and physical protection of conductorsBranch-circuit, feeder, and service load calculations including demand factors
Services, Feeders, and Branch Circuits
10 Q · 12%
Service conductor sizing, ampacity, and minimum size requirementsService disconnecting means: location, rating, and number of disconnectsOvercurrent protection for services and feedersBranch-circuit, feeder, and service load calculations using demand factorsVoltage drop calculations for single-phase and three-phase circuitsOverhead service conductor clearances from grade, roofs, and building openingsGrounding electrode conductor and bonding jumper sizing for AC systemsOutside feeder and branch circuit requirements including clearances and disconnecting means
Overcurrent Protection
8 Q · 10%
Conductor overcurrent protection and ampacity requirements (NEC 240.4, small conductor limits by AWG)Standard ampere ratings for fuses and circuit breakers (NEC Table 240.6(A))Location of overcurrent protective devices in circuits, including feeder and transformer secondary tap rulesAccessibility and placement restrictions for overcurrent devices (height, bathrooms, closets, stairways)Fuse types and requirements: plug fuses, Type S, Edison-base, and cartridge fusesCircuit breaker requirements: marking, indicating, nontamperable, series ratings, and arc energy reduction (240.87)Motor branch-circuit overcurrent protection maximum ratings by motor and device type (Table 430.52)Short-circuit current ratings and calculations for panelboards, switchgear, and protective devices
Grounding and Bonding
8 Q · 10%
Grounding electrode types and installation requirements (NEC 250.52, 250.53)Grounding electrode conductor sizing using Table 250.66Equipment grounding conductor types, sizing, and identification (Table 250.122)Main bonding jumper and system bonding jumper requirements and sizing (Table 250.102(C)(1))Service grounding connections and load-side grounding restrictionsBonding of metal water piping, gas piping, and structural metalSeparately derived system grounding and bondingPermitted connection methods for grounding and bonding conductors
Conductors and Cables
8 Q · 10%
Conductor insulation types, temperature ratings, and permitted applications (THHN, THWN, RHW, XHHW, TW, etc.)Ampacity tables for conductors in raceways, cables, and free air (Tables 310.16 and 310.17)Ambient temperature correction factors and adjustment factors for more than three current-carrying conductorsConductor material, minimum size, stranding, and parallel conductor requirementsNonmetallic-sheathed cable (Types NM and NMC): permitted uses, installation, securing, and ampacity limitationsType AC and Type MC cable: permitted uses, installation, securing, bending radius, and fittingsService-entrance cable (Types SE and USE) and underground feeder cable (Type UF): uses permitted, restrictions, and ampacityConductor properties: DC resistance, circular mil area, dimensions of insulated conductors, and conduit fill calculations
Raceways and Boxes
6 Q · 8%
Conduit fill calculations and conductor count limits by raceway type (EMT, RMC, IMC, PVC, FMC, LFMC, LFNC, ENT)Securing and support intervals for each raceway typePermitted and prohibited uses for each raceway type by location and conditionBox fill calculations: conductor, clamp, device, and equipment grounding conductor volume allowancesBox sizing and dimensions for outlet, device, pull, and junction boxesBox support methods and mounting requirementsConduit bending requirements: bend radius and maximum degrees per runCabinets and cutout boxes: wire-bending space, conductor deflection, and spacing requirements
Special Occupancies and Equipment (Including Swimming Pools)
4 Q · 5%
Swimming pools, spas, and hot tubs: GFCI/SPGFCI protection requirements and equipotential bondingSwimming pools: overhead conductor clearances and underwater luminaire installationMobile and manufactured homes: power supply, disconnecting means, and branch-circuit requirementsRecreational vehicles and RV parks: feeder assemblies, receptacle configurations, and groundingHazardous (classified) locations: Class I, II, and III location classification and protection techniquesHealth care facilities: essential electrical systems, patient care space wiring, and grounding requirementsFire pump power sources, disconnecting means, and wiring requirementsAgricultural buildings: wiring methods, equipotential planes, and GFCI requirements
Low Voltage, Alarms, Signaling Systems, and Communications
2 Q · 2%
Fire alarm circuit types: NPLFA vs. PLFA power sources, branch circuit requirements, and overcurrent protectionFire alarm cable types, listings, and installation applications (FPL, FPLR, FPLP, NPLF, NPLFR, NPLFP)Separation and mixing rules for fire alarm, power, Class 1, and communications conductors in raceways and enclosuresGrounding and bonding of communications system cables, primary protectors, and intersystem bonding terminationCommunications cable types and installation applications by location (CMP, CMR, CMG, CM, CMX) in plenums, risers, and general spacesAntenna system installation: conductor sizing, clearances, supports, discharge units, and groundingCATV and broadband communications system coaxial cable grounding, power limitations, and cable substitutionsLow-voltage lighting system requirements: voltage limitations, isolation, secondary circuit grounding, and branch circuit ratings
Lighting and Signs
4 Q · 5%
Luminaire installation requirements for specific locations (wet, damp, closets, bathtub/shower zones)Recessed luminaire clearances, thermal protection, and Type IC vs. non-IC insulation contact rulesLighting track installation, load ratings, permitted/prohibited locations, and construction requirementsLuminaire support methods, pole-mounted luminaires, and outlet box support requirementsGrounding and bonding of luminaires and lighting equipmentDisconnecting means requirements for fluorescent and LED luminaires with double-ended lampsElectric sign and outline lighting branch circuit requirements, disconnecting means, and grounding/bondingNeon secondary-circuit wiring methods for signs (1000 volts or less vs. over 1000 volts) and transformer/power supply requirements
Safety
4 Q · 5%
Lockout/tagout procedures and establishing an electrically safe work conditionPersonal protective equipment selection and requirements for electrical workArc-flash hazard assessment, boundaries, and equipment labelingShock protection boundaries and minimum approach distancesGround-fault circuit interrupter (GFCI) and assured equipment grounding conductor programEmployer and employee responsibilities for electrical safetyFirst aid availability and medical services requirements for electrical workConfined and enclosed space entry procedures for electrical workers
Key Distinctions
NEC Chapters 1 through 4vsNEC Chapters 5, 6, and 7
Chapters 1-4 apply generally to all electrical installations, while Chapters 5, 6, and 7 cover special occupancies, special equipment, or other special conditions and may supplement or modify the general requirements.
NEC 2023 Section 90.3NEC Chapter 8 (communications systems)vsNEC Chapters 1 through 7
Chapter 8 is not subject to the requirements of Chapters 1 through 7 except where those requirements are specifically referenced in Chapter 8.
NEC 2023 Section 90.3Mandatory rulesvsInformational Notes
Mandatory rules identify actions specifically required or prohibited and use the terms 'shall' or 'shall not,' whereas Informational Notes are informational only and are not enforceable as Code requirements.
NEC 2023 Section 90.5(A)SI (metric) unitsvsInch-pound units
SI units are the Code's measurement system of preference and appear first, with inch-pound units immediately following in parentheses.
NEC 2023 Section 90.9(A), 90.9(B)Individual branch circuitvsMultioutlet (other than individual) branch circuit
Ratings of 10, 15, 20, 30, 40, and 50 amperes apply to other than individual branch circuits (50 A being the maximum standard rating), while individual branch circuits may have other ratings based on the load served.
NEC 2023 Section 210.18Type SO flexible cordvsType SJ flexible cord
Per Table 400.4, Type SO is rated 600 volts for extra-hard usage in damp locations, while Type SJ (junior hard service) is rated for pendant or portable use in damp locations at hard usage.
NEC 2023 Table 400.4Plug fuses rated 15 amperes and lowervsPlug fuses of higher ampere rating
Plug fuses of 15-ampere and lower rating must be identified by a hexagonal configuration of the window, cap, or other prominent part to distinguish them from higher-rated fuses.
NEC 2023 Section 240.50(C)Table 250.66 base GEC sizevs250.66(A) rod, pipe, or plate limitation
Table 250.66 sets the GEC size from the largest ungrounded service conductor (e.g., 2/0 or 3/0 AWG copper requires 4 AWG copper), but where the GEC connects solely to a rod, pipe, or plate electrode it need not be larger than 6 AWG copper.
NEC 2023 Table 250.66GEC to rod, pipe, or plate electrode [250.66(A)]vsGEC to concrete-encased electrode [250.66(B)]
A GEC connected solely to rod/pipe/plate electrodes need not exceed 6 AWG copper (4 AWG aluminum), while one connected solely to concrete-encased electrode(s) need not exceed 4 AWG copper.
NEC 2023 Section 250.66(A)Single-phase voltage dropvsThree-phase voltage drop
Single-phase calculations use a factor of 2 in the numerator, while three-phase balanced loads use 1.732 (square root of 3); using 2 on a three-phase circuit overstates the drop.
Riser-rated (CMR) and plenum (CMP) communications cablevsGeneral-purpose (CMG) communications cable
Only plenum and riser rated cables are permitted in vertical runs penetrating one or more floors; general-purpose and limited-use cables such as CMG are not permitted in risers.
NEC 2023 Section 800.113(D)(1) and (D)(2)Wiring methods exempt from steel plate protection in notched woodvsCables requiring steel plate protection
Rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit, and EMT need no steel plate, while a cable that cannot maintain the 1¼-in. setback must be protected by a steel plate at least 1.6 mm (1/16 in.) thick.
NEC 2023 Section 300.4(A)(2) Exception No. 1Key Terms
Mandatory rule (90.5(A)) NEC 2023 Section 90.5(A)
A Code rule identifying an action that is specifically required or prohibited, characterized by the terms 'shall' or 'shall not.'
Informational Note (90.5(C)) NEC 2023 Section 90.5(C)
Explanatory material that is informational only and not enforceable as a requirement of the Code.
NEC arrangement (90.3) NEC 2023 Section 90.3
The Code consists of an introduction and nine chapters, with Chapter 9 consisting of tables applicable as referenced, plus informative annexes.
Mandatory application (90.4(A)) NEC 2023 Section 90.4(A)
The Code is intended to be suitable for mandatory application by governmental bodies exercising legal jurisdiction over electrical installations, including signaling and communications systems, and for use by insurance inspectors.
Multiwire branch circuit (210.4(A)) NEC 2023 Section 210.4(A)
Branch circuits recognized by Article 210 are permitted to be multiwire circuits.
Dwelling unit voltage limitation (210.6(A)) NEC 2023 Section 210.6(A)
In dwelling units, voltage shall not exceed 120 volts nominal between conductors supplying cord-and-plug-connected loads of 1440 volt-amperes or less.
AFCI protection (210.12(B)) NEC 2023 Section 210.12(B)
All 120-volt, single-phase, 10-, 15-, and 20-ampere branch circuits supplying outlets or devices in listed dwelling locations, including bedrooms, must be AFCI protected by one of the means in 210.12(A)(1) through (A)(6).
Laundry branch circuit (210.11(C)(2)) NEC 2023 Section 210.11(C)(2)
At least one additional 20-ampere branch circuit must be provided to supply the laundry receptacle outlet(s) required by 210.52(F).
Household range branch circuit (210.19(C)) NEC 2023 Section 210.19(C)
Branch-circuit conductors supplying household ranges, wall-mounted ovens, counter-mounted cooking units and other cooking appliances rated 8¾ kW or more require a minimum branch-circuit rating of 40 amperes; the 3-wire neutral must be at least 70% of the circuit rating and not smaller than 10 AWG, and taps from a circuit not exceeding 50 amperes must be at least 20 amperes.
Flexible cord overcurrent protection (400.16) NEC 2023 Section 400.16
Flexible cords not smaller than 18 AWG (and approved tinsel cords of smaller size for specific appliances) are considered protected against overcurrent in accordance with 240.5.
Equipment grounding conductor in flexible cord (250.119(D)) NEC 2023 Section 250.119(D), NEC 400.23
It must be insulated with a continuous outer finish that is green or green with one or more yellow stripes, and such colors shall not be used for any other purpose (400.23).
Grounded conductor on load side (250.24(B)) NEC 2023 Section 250.24(B)
A grounded conductor shall not be connected to non-current-carrying metal parts, to equipment grounding conductors, or reconnected to ground on the load side of the service disconnecting means, except as otherwise permitted.
Supplemental electrode spacing (250.53(A)(3)) NEC 2023 Section 250.53(A)(3)
Multiple rod, pipe, or plate electrodes installed to meet supplemental electrode requirements shall be not less than 1.8 m (6 ft) apart.
Bonding jumper to supplemental electrode (250.53(E)) NEC 2023 Section 250.53(E)
The portion of the bonding jumper that is the sole connection to a supplemental rod, pipe, or plate electrode is not required to be larger than 6 AWG copper or 4 AWG aluminum/copper-clad aluminum.
Chapter 3 wiring method voltage limit (300.2(A)) NEC 2023 Section 300.2(A)
Wiring methods specified in Chapter 3 are for 1000 volts AC, 1500 volts DC nominal or less, where not specifically limited elsewhere in Chapter 3.
Bored-hole setback and minimum cover NEC 2023 Section 300.4(A)(1)
Holes bored through joists, rafters, or wood members must keep the hole edge at least 32 mm (1¼ in.) from the edge of the member, and direct-buried cables or conductors in locations not otherwise specified require 600 mm (24 in.) of cover.
Pull point (EMT bends: 358.24(B) in NEC 2023/2026; 358.26 in NEC 2017/2020) NEC 2023 Section 358.24(B)
A conduit body or other pull point resets the bend count, since a run is limited to 360 degrees of bends between pull points — each section between pull points may have up to 360 degrees.
Manufactured wiring system (604.100(A)) NEC 2023 Section 604.100(A)(1)
Listed Type AC or Type MC cable containing nominal 600-volt, 8 AWG to 12 AWG insulated copper-clad aluminum or copper conductors, except a luminaire tap no longer than 1.8 m (6 ft) to a single luminaire may be as small as 18 AWG.
Formulas to Know
Minimum branch-circuit conductor ampacity with continuous load
Min ampacity = noncontinuous load + (1.25 × continuous load); e.g., 10 A + (16 A × 1.25) = 30 AMinimum overcurrent device rating (branch circuit and feeder)
OCPD ≥ noncontinuous load + (1.25 × continuous load), then use a standard rating per 240.6(A); e.g., 12 A × 1.25 = 15 A; 40 A + (60 A × 1.25) = 115 A → next standard size 125 AMaximum rating of one cord-and-plug-connected utilization equipment not fastened in place
Max = 0.80 × branch-circuit ampere rating; e.g., 15 A × 0.80 = 12 ASingle-phase voltage drop
VD = (2 × K × I × L) ÷ CM, with K = 12.9 for copperThree-phase voltage drop
VD = (1.732 × K × I × L) ÷ CM; e.g., (1.732 × 12.9 × 24 A × 90 ft) ÷ 10,380 cmil = 4.65 VMinimum conductor size for a 3% voltage-drop limit
Allowable VD = 0.03 × system volts; required CM = (2 × K × I × L) ÷ allowable VD, then pick the next larger AWG; e.g., 3.6 V and 11,466 cmil required → 8 AWG (16,510 cmil)Ohm's law
I = E ÷ R and R = E ÷ I; e.g., 240 V ÷ 48 Ω = 5 A; 12 V ÷ 0.5 A = 24 ΩSeries and parallel resistance (and branch current)
Series: R_total = R1 + R2 + …; two resistors in parallel: R = (R1 × R2) ÷ (R1 + R2); total current I = E ÷ R_total; branch current = voltage across the parallel section ÷ branch resistanceApparent power from real power and power factor
S (kVA) = P (kW) ÷ PF; e.g., 200 kW ÷ 0.8 = 250 kVADwelling general load components (Article 220)
Total VA = (floor area × 3 VA/sq ft) + (1500 VA × number of small-appliance circuits) + 1500 VA per laundry circuit; e.g., 7,500 + 4,500 + 1,500 = 13,500 VA