Exam Cheat Sheet · Quick Reference
Oklahoma Unlimited Electrical Journeyman
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%
NEC Article 90 scope, purpose, and code arrangementNEC mandatory vs. permissive rules and explanatory material (shall/shall not vs. shall be permitted)Authority having jurisdiction (AHJ) enforcement and special permissionField terms versus NEC terms (common trade names mapped to NEC article references)Electrical schematic symbols and wiring diagram notationU.S. and metric units of measurement and conversion (linear, area, weight, capacity)Metric prefixes and metric designator/trade sizes for conduitApplied math for electricians: fractions, decimals, equations, geometry of the circle, and trigonometric functions
General Electrical Knowledge
10 Q · 10%
Ohm's Law and power formulas (P, E, I, R relationships)Series, parallel, and combination circuit calculationsElectrical formulas for AC/DC amperes, horsepower, kilowatts, and kVAConductor ampacity tables and temperature ratings (NEC Table 310.16/310.17)Ampacity correction and adjustment factors (ambient temperature and number of conductors)Voltage drop calculations for single-phase and three-phase circuitsConductor types, insulation designations, and application provisionsGrounded conductor identification and use (color coding, terminal marking)
Electrical Installation Requirements
10 Q · 10%
Branch-circuit ratings, conductor sizing, and overcurrent protection requirementsGFCI protection requirements by location and occupancy typeAFCI protection requirements by occupancy and installation typeReceptacle outlet placement and spacing requirements for dwelling and non-dwelling occupanciesLoad calculations using demand factors for lighting, appliances, cooking equipment, and dryersUnderground installation minimum cover requirements by wiring methodWorking space clearances and live-part clearance requirements at electrical equipmentOutside branch circuit and feeder clearances, disconnecting means, and support requirements
Services, Feeders, and Branch Circuits
10 Q · 10%
Service conductor sizing, ampacity, and minimum size requirements (Articles 230, 215)Branch-circuit, feeder, and service load calculations using demand factors (Article 220)Service disconnecting means: location, rating, number, and grouping requirementsOvercurrent protection for services and feeders, including ground-fault protection of equipmentOverhead service conductor clearances: above roofs, from grade, and from building openingsVoltage drop calculations for single-phase and three-phase circuitsMotor branch circuit and feeder conductor sizing and overcurrent protectionOutside branch circuit and feeder requirements: clearances, disconnecting means, and wiring methods
Overcurrent Protection
9 Q · 9%
Protection of conductors by overcurrent device ratings and ampacity (NEC 240.4)Standard ampere ratings for fuses and circuit breakers (NEC 240.6 Table)Location of overcurrent protective devices in circuits, including tap conductor rules (NEC 240.21)Circuit breaker requirements: marking, ratings, arc energy reduction, and series ratings (NEC 240.80–240.87)Fuse types and requirements: plug fuses, cartridge fuses, Type S fuses, and fuseholder rules (NEC 240.50–240.61)Motor branch-circuit overcurrent protective device maximum ratings and settings (NEC 430.52 / Ugly's Table)Short-circuit current calculations and component protection using let-through chartsOvercurrent protection for systems rated over 1000 volts: circuit breakers, power fuses, and feeder requirements (Article 245)
Grounding and Bonding
10 Q · 10%
Grounding electrode types, specifications, and installation requirements (NEC 250.52–250.54)Grounding electrode conductor sizing using Table 250.66Equipment grounding conductor types, sizing, and identification (NEC 250.118–250.122)Main bonding jumper and system bonding jumper installation and sizingSupply-side bonding jumper sizing using Table 250.102(C)(1)Bonding of piping systems, structural metal, and service equipment (NEC 250.92–250.104)Grounding of separately derived AC systems (NEC 250.30)General requirements for grounded vs. ungrounded systems and effective ground-fault current path
Conductors and Cables
8 Q · 8%
Conductor ampacity tables (raceway, cable, free air, and direct burial installations)Ampacity correction and adjustment factors (ambient temperature and number of current-carrying conductors)Conductor insulation types, temperature ratings, and application provisionsCable type uses permitted and uses not permitted (NM, MC, AC, SE, USE, UF, MI, TC, ITC, MV, and specialty types)Securing, supporting, and bending radius requirements for cable typesConductor sizing, materials, and minimum size requirements (copper, aluminum, copper-clad aluminum)Conductor fill calculations and maximum number of conductors in conduit or tubingMedium voltage (Type MV) cable construction, shielding, insulation levels, and ampacity
Raceways and Boxes
7 Q · 7%
Conduit fill calculations and conductor count limits (Chapter 9, Table 1)Securing and supporting requirements for each raceway typeUses permitted and uses not permitted for metallic conduit systems (RMC, IMC, EMT, FMC, LFMC, FMT)Uses permitted and uses not permitted for nonmetallic conduit systems (PVC, RTRC, HDPE, NUCC, ENT, LFNC)Box fill calculations and volume allowances (Article 314)Pull and junction box sizing for straight, angle, and U pullsBox and enclosure support methods and mounting requirementsCable tray types, fill limits, ampacity, and grounding requirements
Special Occupancies and Equipment (Including Swimming Pools)
10 Q · 10%
Hazardous location classification (Class I, II, III; Divisions 1 and 2; Zone 0/1/2 and Zone 20/21/22)Wiring methods and sealing requirements in hazardous classified locationsProtection techniques for hazardous locations (explosionproof, intrinsically safe, pressurized, dusttight, encapsulation)Health care facility essential electrical systems (Type 1 and Type 2 EES, life safety and critical branches)Patient care space wiring, grounding, bonding, and receptacle requirementsSpecial occupancy area classification (commercial garages, aircraft hangars, motor fuel dispensing, bulk storage, spray application)Electrical requirements for mobile homes, manufactured homes, recreational vehicles, and park trailersElevators, escalators, cranes, and hoists electrical installation requirements
Low Voltage, Alarms, Signaling Systems, and Communications
2 Q · 2%
Fire alarm circuit wiring methods and installation requirements (NPLFA and PLFA)Power-limited fire alarm (PLFA) cable types, listings, and substitutionsCircuit separation and mixing rules for Class 2, Class 3, and communications circuitsEmergency system wiring, transfer equipment, and alternate power sourcesGrounding and bonding of communications, antenna, and broadband systemsCommunications cable types and installation by building location (plenum, riser, general-purpose)Legally required standby and critical operations power system requirementsLow-voltage lighting system voltage limits, isolation, and branch circuit requirements
Lighting and Signs
10 Q · 10%
Luminaire location requirements (wet, damp, corrosive, bathtub/shower zones, clothes closets)Luminaire support methods and weight limitationsGrounding and bonding of luminaires and lighting equipmentWiring methods and conductor requirements within luminairesRecessed luminaire installation (Type IC, thermal protection, clearances from insulation and combustibles)Lighting track installation, construction, and restrictionsElectric signs and outline lighting branch circuits, disconnecting means, and groundingEnergy cost calculations and lamp efficiency comparisons
Safety
4 Q · 4%
Lockout/tagout and electrically safe work condition proceduresPersonal protective equipment (PPE) selection and requirementsElectrical shock protection boundaries and approach limitsArc-flash hazard identification and equipment labelingFall protection systems and requirementsFire protection, prevention, and flammable liquid storageConfined space entry requirements and permit proceduresLadder and stairway safety requirements
Motors and Transformers
6 Q · 6%
Motor branch-circuit conductor sizing (125% rule, NEC 430.22)Branch-circuit short-circuit and ground-fault protective device selection (NEC Table 430.52)Motor overload protection requirements and trip current percentages (NEC 430.32)Motor disconnecting means type, location, and rating requirements (NEC 430.102–430.110)Motor feeder conductor sizing and feeder overcurrent protection (NEC 430.24, 430.62)Transformer overcurrent protection sizing for primary and secondary (NEC 450.3, Tables 450.3(A) and 450.3(B))Transformer calculations: kVA sizing, primary/secondary current, turns ratio, and short-circuit currentHermetic refrigerant motor-compressor branch-circuit and overload protection requirements (NEC Article 440)Delta and wye transformer connections (line vs phase voltage and current, neutral current, balancing)
Key Distinctions
Class I, Division 1vsClass III, Division 1
Class I, Division 1 is hazardous because ignitible concentrations of flammable gases or flammable/combustible liquid-produced vapors can exist under normal operating conditions, while Class III, Division 1 involves easily ignitible fibers or combustible flyings that are handled, manufactured, or used but are not normally suspended in air in ignitible quantities.
NEC 2023 Section 500.5(B)(1)Class I, Group AvsClass II, Group E
Group A is specifically acetylene (a flammable gas), whereas Group E atmospheres contain combustible metal dusts such as aluminum, magnesium, and their commercial alloys.
NEC 2023 Section 500.6(A)(1)Mandatory rules ('shall'/'shall not')vsInformational Notes
Mandatory rules use 'shall' or 'shall not' to identify required or prohibited actions, while Informational Notes are explanatory material included for information only and are not enforceable as Code requirements.
NEC 2023 Section 90.5(A)NEC Chapters 1–4vsNEC Chapter 8
Chapters 1, 2, 3, and 4 apply generally to all installations (Chapters 5, 6, 7 cover special occupancies/equipment/conditions), while Chapter 8 covers communications systems and is not subject to Chapters 1 through 7 except where specifically referenced in Chapter 8.
NEC 2023 Section 90.3Straight pull box sizingvsAngle pull box sizing
For straight pulls the box length must be at least 8 times the trade size of the largest raceway, while for angle pulls the distance from the entry wall to the opposite wall must be at least 6 times the largest raceway trade size plus the sum of the trade sizes of the other raceways on that same wall.
NEC 2023 Section 314.28(A)(1)Motor branch-circuit conductors (430.22)vsMotor disconnecting means (430.110(A))
Branch-circuit conductors for a single motor must be sized at not less than 125% of the motor full-load current, while the disconnecting means must have an ampere rating of at least 115% of the motor nameplate full-load current.
NEC 2023 Section 430.22(A)Motor branch-circuit conductor sizing (430.22)vsMotor feeder conductor sizing (430.24)
A single-motor branch circuit uses 125% of that motor's FLC, while a feeder supplying several motors uses 125% of the largest motor's FLC plus 100% of all remaining motor FLCs.
NEC 2023 Table 430.250, Section 430.22, Table 310.16, Article 701Emergency power source general duration (700.12(C))vsStorage batteries/UPS for emergency illumination (700.12(C)(4))
The general emergency power source must supply the total load for not less than 2 hours, while storage batteries and UPS used for emergency illumination must maintain the load for a minimum of 1½ hours without voltage falling below 87½ percent of nominal.
NEC 2023 Section 700.12(C)EGC in a flexible cord (250.122(E))vsEGC sized from Table 250.122
For a flexible cord whose largest circuit conductor is 10 AWG or smaller, the EGC must be not smaller than 18 AWG copper and not smaller than the circuit conductors (14 AWG on a 15-A circuit), whereas general equipment grounding conductors are sized from Table 250.122 by OCPD rating (e.g., 6 AWG copper for a 200-A device).
NEC 2023 Section 250.122(E)3% voltage drop (feeder alone)vs5% voltage drop (feeder plus branch circuit)
Informational Notes recommend (not require) that feeders be sized to limit voltage drop to 3 percent at the farthest outlet and that the combined feeder plus branch-circuit drop to the farthest outlet not exceed 5 percent.
NEC 2023 Section 215.2(A)(4)Raceway-supported enclosure containing a device (314.23(F))vsRaceway-supported enclosure without devices (314.23(E))
An enclosure containing a device (other than splicing devices) or supporting a luminaire must be supported by two or more conduits threaded wrenchtight and secured within 450 mm (18 in.) of the enclosure, a tighter requirement than the 900 mm (3 ft) rule for enclosures without devices.
NEC 2023 Section 314.23(F)XHHW rating in dry/damp locationsvsXHHW rating in wet locations
Type XHHW is rated 90°C (194°F) in dry and damp locations but only 75°C (167°F) in wet locations.
NEC 2023 Table 310.4(1)MV cable ampacity ambient (315.60(E))vsGeneral wiring ampacity ambient (Tables 310.16/310.17)
Ampacity tables for MV cables with conductors in air are based on a 40°C ambient, while the standard general-wiring ampacity tables are based on 30°C ambient.
NEC 2023 Section 315.60(E)Key Terms
Authority Having Jurisdiction (AHJ) NEC 2023 Section 90.4(B)
The enforcement authority responsible for making interpretations of Code rules, deciding on approval of equipment and materials, and granting special permission contemplated in the rules (NEC 90.4).
Mandatory rule NEC 2023 Section 90.5(A)
A Code rule characterized by the terms 'shall' or 'shall not,' identifying actions that are specifically required or prohibited.
Measurement system of preference NEC 2023 Section 90.9(A), 90.9(B)
The NEC uses the International System of Units (SI) as its preferred system, with SI units appearing first and inch-pound units immediately following in parentheses.
Class I, Division 1 location NEC 2023 Section 500.5(B)(1)
A location where ignitible concentrations of flammable gases, flammable liquid-produced vapors, or combustible liquid-produced vapors can exist under normal operating conditions.
Class III, Division 1 location NEC 2023 Section 500.5(D)(1)
A location where easily ignitible fibers or materials producing combustible flyings are handled, manufactured, or used, though not normally suspended in air in ignitible quantities.
Explosionproof protection technique NEC 2023 Section 500.7(A)
A protection technique permitted for equipment in Class I, Division 1 or Division 2 locations per NEC 500.7(A).
Autoignition temperature (Class I equipment limit) NEC 2023 Section 500.8(B)(1)
The temperature of the specific gas or vapor that no exposed surface of Class I equipment may exceed in operation (NEC 500.8(B)(1)).
NPT-threaded entry (hazardous locations) NEC 2023 Section 500.8(E)(1)
An entry into explosionproof equipment that must be made up with at least five threads fully engaged; an exception permits four and one-half threads for listed equipment with factory-threaded entries.
Multiwire branch circuit NEC 2023 Section 210.4(C)
A branch circuit that shall supply only line-to-neutral loads (with exceptions for single utilization equipment or where all ungrounded conductors are opened simultaneously) and must have a means to simultaneously disconnect all ungrounded conductors at the point of origination.
Service disconnecting means NEC 2023 Section 230.71(B)
Each service shall have only one disconnecting means unless 230.71(B) applies, which permits two to six service disconnects—six being the maximum for a single service.
Grounding electrode conductor (GEC) NEC 2023 Table 250.66
The conductor sized from Table 250.66 by service-entrance conductor size—for example, 2 AWG copper for 4/0 AWG copper service conductors and 1/0 AWG copper for 500 kcmil copper (over 350 through 600 kcmil).
Supplemental electrode bonding jumper NEC 2023 Section 250.53(E)
Where the supplemental electrode is a rod, pipe, or plate, the portion of the bonding jumper that is the sole connection to it is not required to be larger than 6 AWG copper or 4 AWG aluminum/copper-clad aluminum (NEC 250.53(E)).
Plug fuse identification (15 A and lower) NEC 2023 Section 240.50(C)
Plug fuses rated 15 amperes or less must be identified by a hexagonal configuration of the window, cap, or other prominent part to distinguish them from higher-rated fuses.
Manufactured wiring system cable NEC 2023 Section 604.100(A)(1)
Cable containing nominal 600-volt, 8 AWG to 12 AWG insulated conductors, making 12 AWG the smallest permitted conductor size (NEC 604.100(A)(1)).
Portable power feeder cable (over 2000 V) NEC 2023 Section 400.44(A)
Cable whose conductors shall be 6 AWG copper or larger with flexible stranding, that shall not contain splices, and, for 5001–25,000 V, has a minimum bending radius of eight times the overall cable outer diameter; Type SH is the single-conductor designation rated 2001–25,000 V.
Pull point (raceway bends) NEC 2023 Section 358.24(B)
A point such as a conduit body or box that resets the 360° maximum bend limit, so each section between pull points may contain up to 360° of bends (NEC 358.26).
Flexible cord overcurrent protection NEC 2023 Section 240.5(B)(3)
Flexible cords not smaller than 18 AWG (and tinsel cords or equivalent smaller cords approved for specific appliances) are considered protected against overcurrent by the branch-circuit overcurrent device at the supply end.
Emergency lighting availability NEC 2023 Section 700.12
Emergency lighting must be available within the time required for the application, not to exceed 10 seconds after failure of the normal supply (NEC 700.12).
Formulas to Know
Minimum conductor ampacity for continuous and noncontinuous loads (branch circuit, feeder, and service)
Minimum ampacity = (100% × noncontinuous load) + (125% × continuous load); e.g., 80 A cont. + 30 A noncont. → (80 × 1.25) + 30 = 130 A; 48 A cont. + 30 A noncont. → 60 + 30 = 90 A; 38 A cont. + 55 A noncont. → 47.5 + 55 = 102.5 ALoad current from VA (single-phase and three-phase)
Single-phase: I = VA ÷ E (e.g., 48,000 ÷ 240 = 200 A; 30,000 ÷ 240 = 125 A). Three-phase: I = VA ÷ (E × 1.732) (e.g., 86,500 ÷ (208 × 1.732) = 240 A; 150,000 ÷ (480 × 1.732) = 180.4 A; 75,000 ÷ (208 × 1.732) = 208.2 A)Motor branch-circuit conductor ampacity (single motor)
Ampacity ≥ 125% × motor FLC from Table 430.250 (e.g., 40 HP, 460 V, 3φ = 52 A → 52 × 1.25 = 65 A, requiring 6 AWG THWN copper at 75°C)Motor feeder conductor ampacity (multiple motors, 430.24)
Ampacity ≥ (125% × largest motor FLC) + (100% × sum of other motor FLCs); e.g., 65 × 1.25 + 40 = 121.25 A; 34 × 1.25 + 21 + 14 = 77.5 A; 30.8 × 1.25 + 24.2 = 62.7 A. Add continuous non-motor load at 125% (e.g., 65 × 1.25 + 30 × 1.25 = 118.75 A)Motor branch-circuit short-circuit/ground-fault device maximum and disconnect minimum
Use Table 430.250 FLC (not nameplate): inverse-time CB = 250% FLC for squirrel-cage (34 × 2.50 = 85 A → next standard 90 A) and 150% FLC for wound-rotor (40 × 1.50 = 60 A); time-delay fuse = 175% FLC (59.4 × 1.75 = 103.95 A → next standard 110 A); next standard size permitted per 430.52(C)(1) Ex.1 and 240.6(A). Disconnect ≥ 115% of motor nameplate FLC.Generator output feeder conductor sizing (445.13)
Ampacity ≥ 115% × generator nameplate current; e.g., 150 kVA at 480 V 3φ → 180.4 A × 1.15 = 207.5 A → 4/0 AWG copper THWN (230 A at 75°C)Pull box minimum dimensions (314.28)
Straight pull: length ≥ 8 × trade size of largest raceway (8 × 3 in. = 24 in.). Angle pull: distance to opposite wall ≥ (6 × largest raceway trade size on that wall) + sum of the other raceway trade sizes on that wall (6 × 3 + 2 + 1.5 = 21.5 in.)Minimum box volume (box fill, 314.16(B))
Sum allowances from Table 314.16(B): each conductor = its volume (12 AWG = 2.25 cu in., 14 AWG = 2.00 cu in.); all EGCs together = 1 allowance based on the largest EGC; each device yoke = 2 × volume of largest conductor connected to it; all internal cable clamps = 1 × volume of largest conductor in box. Example: 9.00 + 4.00 + 2.00 + 4.50 + 2.25 = 21.75 cu in.Three-phase voltage drop
VD = (1.732 × K × I × D) ÷ CM; with K = 12.9 for copper, I = 85 A, D = 250 ft, 1/0 AWG = 105,600 CM → VD = 474,785 ÷ 105,600 = 4.50 VAdjusted (corrected) conductor ampacity
Adjusted ampacity = base ampacity from Table 310.16 (use conductor's temperature column) × ambient temperature correction × conductor-count adjustment factor; e.g., 2 AWG THHN 90°C = 130 A × 0.91 (40°C) × 0.80 (6 CCCs) = 94.6 A. Flexible cords: 7–9 current-carrying conductors = 70%; portable feeder cable wound 3 layers on a reel = 0.45.