Exam Cheat Sheet · Quick Reference
Idaho Journeyman Electrician Exam
Idaho · 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
270 min
Administered by
PSI Services Contractor
Format
Reference materials allowed
Idaho State Portion 100 questions
General Electrical Knowledge
13 Q · 13%
Ohm's Law formulas and calculations (voltage, current, resistance, power)Series circuit rules and calculationsNEC scope: installations covered and not coveredNEC code arrangement and chapter organizationMandatory vs. permissive vs. explanatory rule languageCommon electrical distribution systems and conductor color codingAuthority having jurisdiction (AHJ) enforcement and special permissionNEC units of measurement (SI and inch-pound systems)
Wiring and Protection
25 Q · 25%
Conductor ampacity tables and correction/adjustment factors (Articles 310.15-310.21)Grounding and bonding requirements including grounding electrode systems and conductors (Article 250)Protection of conductors against overcurrent including fuses and circuit breakers (Article 240)Underground wiring installation requirements and minimum cover depths (Article 300.5)Physical protection of cables and raceways through structural members (Article 300.4)Service entrance conductors, disconnecting means, and overcurrent protection (Article 230)Conductor types, insulation ratings, and permitted uses by location (Article 310.4 and 310.10)Feeder conductor sizing, overcurrent protection, and identification requirements (Article 215)Wiring methods permitted in ducts, plenums, and air-handling spaces (Article 300.22)Electrical continuity and mechanical continuity requirements for raceways and conductors (Articles 300.10–300.13)Equipment grounding conductor types, sizing, and identification (Article 250.118–250.122)Bonding requirements for piping systems, structural metal, and service equipment (Article 250.92–250.104)
+3 more
Wiring Methods and Materials
19 Q · 19%
Box fill calculations and conductor count requirements (Article 314.16)Conductor ampacity tables and temperature ratings (Article 310.14-310.21)Protection of cables and raceways against physical damage (Article 300.4)Underground installation requirements and minimum cover depths (Article 300.5)Support and securing of boxes and enclosures (Article 314.23)Wiring in ducts, plenums, and air-handling spaces (Article 300.22)Pull and junction box sizing for conductors 4 AWG and larger (Article 314.28)General raceway installation requirements including continuity, sealing, and conductor grouping (Article 300.6-300.20)Conductor identification requirements for grounded, equipment grounding, and ungrounded conductors (Article 310.6)Conductor types and insulation applications for dry, damp, and wet locations (Article 310.10)Minimum conductor size and material requirements including aluminum AA-8000 alloy (Article 310.3)Firestopping requirements for electrical penetrations through fire-rated assemblies (Article 300.21)
+2 more
Equipment for General Use
19 Q · 19%
Fixture wire types, temperature ratings, and voltage limitations (Article 402)Receptacle installation, grounding, and replacement requirements (Article 406)Luminaire location requirements for wet, damp, and specific locations (Article 410)Switch ratings, connections, and installation requirements (Article 404)Flexible cord types, permitted and prohibited uses, and ampacity (Article 400)Luminaire support methods and grounding requirements (Article 410)Lighting track installation requirements and restrictions (Article 410 Part XIV)Recessed luminaire clearance, thermal protection, and wiring requirements (Article 410)Motor branch-circuit conductor sizing, overload protection, and disconnecting means (Article 430)Air-conditioning and refrigeration equipment conductor and OCPD sizing (Article 440)Generator installation and overcurrent protection (Article 445)Transformer overcurrent protection and installation requirements (Article 450)
Special Occupancies
12 Q · 12%
Hazardous location classification (Class I, II, III; Division 1 and 2) and area classification requirementsWiring methods and sealing requirements for Class I, II, and III hazardous locationsCommercial garages and motor fuel dispensing facility area classification and wiring requirementsHealth care facility essential electrical systems (Type 1 and Type 2 EES), life safety and critical branch requirementsPatient care space wiring, grounding, bonding, and receptacle requirements in health care facilitiesSwimming pool and spa electrical installation requirements including GFCI protection, bonding, and luminaire placementMobile and manufactured home electrical systems including power supply, branch circuits, grounding, and service equipmentAssembly occupancy wiring methods, temporary wiring, and supply requirements
Special Equipment
6 Q · 6%
Wiring methods and conductor types for cranes and hoists (Article 610)Disconnecting means requirements for cranes, hoists, and elevatorsOvercurrent and overload protection for crane, hoist, and elevator circuitsElevator and escalator branch circuits, feeder sizing, and demand factors (Article 620)Generator installation, marking, overcurrent protection, and disconnecting means (Article 445)Electric signs and outline lighting disconnects, branch circuits, and grounding (Article 600)Industrial machinery nameplate data, supply conductor sizing, and short-circuit current rating (Article 670)Grounding and bonding requirements for cranes, hoists, and elevators
Special Conditions
6 Q · 6%
Hazardous location classification (Class I, II, III and Division 1 and 2)Protection techniques for hazardous locations (explosionproof, dust-ignitionproof, intrinsically safe, purged/pressurized, etc.)Solar PV system circuit requirements (maximum voltage, current calculations, overcurrent protection, and arc-fault protection)Solar PV rapid shutdown requirements and labelingHealth care facility essential electrical systems (Type 1 and Type 2 EES branches)Wiring methods and sealing requirements for Class I hazardous locationsHealth care facility patient care space grounding, bonding, and isolated power systemsPark trailer electrical systems (power supply, branch circuits, grounding, and GFCI requirements)
Key Distinctions
Mandatory rulesvsPermissive rules
Mandatory rules use 'shall' or 'shall not' (90.5(A)), while permissive rules use 'shall be permitted' or 'shall not be required' (90.5(B)).
NEC 2023 Section 90.5(A) and 90.5(B)Chapter 8 (communications systems)vsChapters 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 90.3Elevator raceway fill (Article 620.33)vsGeneral conduit fill (Chapter 9, Table 1)
In elevator installations the sum of conductor cross-sectional areas shall not exceed 40 percent of the raceway interior (the 50 percent figure applies to wireways under 620.32), whereas general Chapter 9 Table 1 fill varies with conductor count (40% for more than two conductors, 31% for exactly two).
NEC 2023 Section 620.3312 AWG copper THWN (75°C)vs12 AWG copper THWN-2 (90°C)
In raceway with not more than three current-carrying conductors at 30°C, Table 310.16 gives 25 amperes in the 75°C column for THWN versus 30 amperes in the 90°C column for THWN-2.
NEC 2023 Table 310.16Direct-buried cables/conductors covervsRigid metal conduit or IMC cover
In all locations not otherwise specified in Table 300.5(A), direct burial requires 600 mm (24 in.) of cover while RMC or IMC requires only 150 mm (6 in.).
NEC 2023 Table 300.5(A)RMC under a one- and two-family dwelling drivewayvsRMC in 'all locations not specified'
A dwelling driveway is a specified location requiring 450 mm (18 in.) of cover, whereas the 150 mm (6 in.) RMC figure applies only to locations not specified (general streets, roads, alleys, driveways and parking lots require 600 mm/24 in. for all wiring methods).
NEC 2023 Table 300.5(A)Overhead service clearance over public streets/alleysvsOverhead service clearance over residential property and driveways
Conductors not over 1000 volts need 5.5 m (18 ft) over public streets, alleys, roads and parking areas subject to truck traffic, but only 3.7 m (12 ft) over residential property and driveways where voltage does not exceed 300 volts to ground.
NEC 2023 Section 230.24(B)Minimum copper conductor sizevsMinimum aluminum/copper-clad aluminum conductor size
For general wiring up to and including 2000 volts the minimum is 14 AWG copper versus 12 AWG aluminum or copper-clad aluminum, except as permitted elsewhere in the Code; for overhead service conductors the minimums are 8 AWG copper versus 6 AWG aluminum.
NEC 2023 Section 310.3(A)Grounded (neutral) conductor identificationvsUngrounded conductor identification
In a 120/240-volt single-phase three-wire system the grounded neutral is white or gray, while the ungrounded conductors are black (line one) and red (line two); in a 120/208-volt wye the C phase ungrounded conductor is blue.
Ugly's Electrical References, 2023 ed., Common Electrical Distribution Systems, Page 13One 360° bend limit per runvs360° between pull points
NEC 358.26 limits bends to 360° between pull points, so adding a conduit body (a pull point) mid-run allows each section on either side of it to contain up to 360° of bends.
NEC 2023 Section 358.24(B)Equipment grounding conductors in box fillvsDevice yokes and pigtails in box fill
Up to four EGCs count as one volume allowance (based on the largest EGC) with 1/4 allowance for each additional EGC, whereas a device yoke counts as two allowances and a pigtail wholly inside the box is not counted at all.
NEC 2023 Section 314.16(B)(5)Steel plate protection thickness requiredvs2.0 mm (5/64 in.) plate
The Code requires steel plates or bushings at least 1.6 mm (1/16 in.) thick for protection against nails and screws; 2.0 mm is not the Code figure.
NEC 2023 Section 300.4(A)(1)Service-entrance cable support within 300 mm (12 in.)vsSupport within 450 mm (18 in.)
NEC 230.51(A) requires support by straps or other approved means within 300 mm (12 in.) of every service head, gooseneck, or connection to a raceway or enclosure — not 450 mm (18 in.).
NEC 2023 Section 230.51(A)Key Terms
Purpose of the NEC (90.1(A)) NEC 2023 Section 90.1(A)
The practical safeguarding of persons and property from hazards arising from the use of electricity; the Code is not intended as a design specification or instruction manual for untrained persons.
Code arrangement (90.3) NEC 2023 Section 90.3
The NEC is divided into an introduction and nine chapters: Chapters 1-4 apply generally, Chapters 5-7 apply to special conditions, Chapter 8 covers communications, and Chapter 9 consists of tables.
Free conductor length (300.14) NEC 2023 Section 300.14
At least 150 mm (6 in.) of free conductor, measured from where it emerges from its raceway or cable sheath in the box, must be left at each outlet, junction, and switch point for splices or connections.
Conductors of the same circuit (300.3(B)) NEC 2023 Section 300.3(B)
All conductors of the same circuit, including the grounded conductor and all equipment grounding and bonding conductors, must be contained in the same raceway, conduit body, auxiliary gutter, cable tray, cablebus, trench, cable, or cord unless otherwise permitted.
Bored-hole and notch protection (300.4(A)) NEC 2023 Section 300.4(A)(1)
Holes in wood members must be bored so the hole edge is at least 32 mm (1 1/4 in.) from the member edge; where that distance can't be kept, or where cables lie in notches, a steel plate at least 1.6 mm (1/16 in.) thick protects against nails and screws.
Parallel-to-framing clearance (300.4(D)) NEC 2023 Section 300.4(D)
Cables and raceways run parallel to framing members must have their nearest outside surface at least 32 mm (1 1/4 in.) from the edge where nails or screws are likely to penetrate, or be protected by steel plate or sleeve.
Emergence from grade protection (300.5(D)(1)) NEC 2023 Section 300.5(D)(1)
Direct-buried conductors and cables emerging from grade must be protected by enclosures or raceways from the required minimum cover depth to at least 2.5 m (8 ft) above finished grade.
Support of conductors in vertical raceways (Table 300.19(A)) NEC 2023 Table 300.19(A)
Copper conductors 18 AWG through 1/0 AWG in vertical raceways must be supported at intervals not greater than 30 m (100 ft), with support at the top and at intermediate points.
Stranding requirement (310.3(C)) NEC 2023 Section 310.3(C)
Conductors 8 AWG and larger installed in raceways must be stranded unless specifically permitted or required elsewhere in the Code to be solid.
Table 310.16 ambient basis NEC 2023 Section 310.16
Ampacities in Table 310.16 are based on a 30°C (86°F) ambient temperature; other ambients require correction factors from Table 310.15(B)(1)(1).
Ampacity adjustment factor (Table 310.15(C)(1)) NEC 2023 Table 310.15(C)(1)
Where more than three current-carrying conductors are in a raceway or cable, ampacity is reduced — 7 through 9 conductors are adjusted to 70 percent of the table values.
Open service conductor height (230.26) NEC 2023 Section 230.50(B)(2)
Individual open conductors and cables, other than service-entrance cables, shall not be installed within 3.0 m (10 ft) of grade level or where exposed to physical damage; underground service conductors must be protected per 300.5.
Supplemental grounding electrode spacing (250.53(A)(3)) NEC 2023 Section 250.53(A)(3)
Where multiple rod, pipe, or plate electrodes are installed to meet the requirement, they must be not less than 1.8 m (6 ft) apart.
PV array boundary (690.12(B)) NEC 2023 Section 690.12(B)
For rapid shutdown, the array boundary is 305 mm (1 ft) from the array in all directions; controlled conductors outside that boundary and more than 1 m (3 ft) from the array, or inside a building, must be limited to 30 volts or less within 30 seconds of initiation.
Stationary generator listing (445.6) NEC 2023 Section 445.6
Stationary generators must be listed, except one-of-a-kind or custom-manufactured units, which are permitted to be field labeled.
Clothes closet luminaire clearance (410.16) NEC 2023 Section 410.16(C)(4)
Surface-mounted fluorescent or LED luminaires in clothes closets must be on the wall above the door or on the ceiling with at least 150 mm (6 in.) clearance to the nearest point of a storage space.
Category 1 operating room receptacles (517.19(C)(1)) NEC 2023 Section 517.19(C)(1)
Each operating room in a Category 1 space must have a minimum of 36 receptacles divided among at least two branch circuits from the normal system and the equipment system or critical branch.
Formulas to Know
Ohm's Law (current, resistance, voltage)
I = W ÷ E (1500 W ÷ 120 V = 12.5 A); R = E ÷ I (240 V ÷ 8 A = 30 Ω); E = I × R (10 A × 12 Ω = 120 V)Power in watts
P = E × I (volts × amperes); when voltage and resistance are known, P = E² ÷ R (240² ÷ 20 = 2880 W)Minimum feeder / service-entrance conductor ampacity with continuous load
Ampacity = noncontinuous load + (125% × continuous load); e.g., 30 A + (1.25 × 100 A) = 155 A; 40 A + (1.25 × 60 A) = 115 ADwelling general load calculation (Article 220)
Total VA = (floor area in sq ft × 3 VA/sq ft) + (1500 VA × number of small-appliance circuits) + (1500 VA × number of laundry circuits); multiply per-unit total by number of units for multifamily before demand factors; dwelling units only: a retail store uses the Table 220.42(A) unit load, 1.9 VA/sq ft, plus 180 VA per receptacle outletAmpacity of conductors in parallel
Total ampacity = table ampacity of one conductor × number of parallel sets (350 kcmil Cu at 90°C = 350 A; 2 sets = 700 A)Ampacity adjustment for more than three current-carrying conductors
Adjusted ampacity = table ampacity × adjustment factor; for 7-9 conductors the factor is 70 percentMinimum straight pull box length
Length ≥ 8 × trade size of largest raceway (8 × 3 in. = 24 in. / 610 mm)Conduit fill and maximum conductor count
Allowed area = raceway internal area × fill percent (40% for more than two conductors, 31% for exactly two); max conductors = allowed area ÷ area per conductor, dropping fractions below 0.8 (Note 7) — e.g., 0.814 in² ÷ 0.0507 in² = 16.06 → 16Box fill volume allowances
Allowances = insulated conductors + 1 for all EGCs up to four (+1/4 for each additional EGC) + 1 for all clamps + 2 per device yoke (pigtails wholly inside the box not counted); required volume = allowances × volume per conductor size (2.00 cu in for 14 AWG); spare capacity = box volume − required volume, divided by volume per conductorEMT offset bend first-mark location
First mark = measured distance to obstruction + shrink (24 in. + 1-7/8 in. = 25-7/8 in.), with the second mark set at the offset spacing (7 in.) beyond it