Exam Cheat Sheet · Quick Reference

Idaho - ID 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
75%
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 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)
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)
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 NEC RulesvsPermissive NEC Rules

Mandatory rules use 'shall' or 'shall not' (required or prohibited actions), while permissive rules use 'shall be permitted' or 'shall not be required'.

Article 90.5(A)
Series Circuit CurrentvsSeries Circuit Resistance

In a series circuit, current is equal in all parts (IT = I1 = I2 = I3), while total resistance is the sum of all individual resistances (RT = R1 + R2 + R3).

Series Circuits
NEC Chapters 1–7vsNEC Chapter 8 (Communications Systems)

Chapters 1–7 apply generally to all covered installations, while Chapter 8 is independent and not subject to Chapters 1–7 except where specifically referenced therein.

NEC 90.3
Direct Burial Cable (underground cover)vsRigid Metal Conduit / IMC (underground cover)

Direct burial cables require a minimum cover of 600 mm (24 in.) in general locations, while rigid metal conduit or IMC requires only 150 mm (6 in.).

NEC Table 300.5(A)
Bored Hole Protection (wood members)vsNotched Wood Member Protection

Bored holes must keep the edge at least 32 mm (1-1/4 in.) from the wood edge or a steel plate is required, while cables in notches must always be covered by a steel plate at least 1.6 mm (1/16 in.) thick.

NEC 300.4(A)(1)
120/240 V Single-Phase Neutral Conductor Colorvs120/240 V Single-Phase Ungrounded Conductor Colors

The grounded neutral conductor is white or gray, while the two ungrounded conductors are black (L1) and red (L2).

Ugly's Electrical References, Common Electrical Distribution Systems
120/208 V Three-Phase Wye (C phase color)vs120/240 V Delta High-Leg (B phase color)

In a 120/208 V three-phase four-wire wye system the C phase is blue, while in a 120/240 V delta high-leg system the B phase (high leg) is orange.

Ugly's Electrical References, Common Electrical Distribution Systems
NEC PurposevsNEC Design Specification

The NEC's purpose is the practical safeguarding of persons and property from electrical hazards; it is explicitly NOT intended as a design specification or instruction manual for untrained persons.

Article 90.2(A)
Vertically Operated Switch Handle – Up PositionvsVertically Operated Switch Handle – Down Position

Per NEC 404.7, the up position of a vertically operated switch handle is the closed (on) position, implying the down position is the open (off) position.

NEC 404.7
Elevator Raceway Fill (Article 620)vsGeneral Wiring Raceway Fill (Chapter 9)

Elevator installations allow a maximum of 50% raceway fill per Article 620.33, which differs from the standard fill percentages in Chapter 9, Table 1 used for general wiring.

Article 620.33
Ohm's Law (I = E ÷ R)vsPower Formula / Watt's Law (I = P ÷ E)

Ohm's Law calculates current from voltage and resistance (I = E ÷ R), while Watt's Law calculates current from power and voltage (I = P ÷ E); both appear on the Ohm's Law wheel but are technically distinct formulas.

Ugly's Electrical References, Ohm's Law
Continuous Load Feeder Sizing (125%)vsAmpacity Adjustment for 7–9 Conductors (70%)

Feeder conductors must be sized at 125% of continuous loads per NEC 215.2(A)(1), while conductors in a raceway containing 7–9 current-carrying conductors must have their ampacity derated to 70% per NEC Table 310.15(C)(1).

NEC 215.2(A)(1)

Key Terms

NEC Purpose (Article 90.1(A)) Article 90.2(A)
Per NEC 90.1(A), the Code exists for the practical safeguarding of persons and property from hazards arising from the use of electricity, and is not a design specification.
Authority Having Jurisdiction (AHJ) – Article 90.4 Article 90.4(B)
Per NEC Article 90.4, the AHJ is responsible for making interpretations of NEC rules, approving equipment and materials, and granting special permissions contemplated by the Code.
Mandatory Rule – Article 90.5(A) Article 90.5(A)
Per NEC 90.5(A), a mandatory rule requires or prohibits a specific action and is identified by the terms 'shall' or 'shall not'.
Permissive Rule – Article 90.5(B) NEC 90.5(A) and 90.5(B)
Per NEC 90.5(B), a permissive rule identifies actions that are allowed but not required, and is identified by the terms 'shall be permitted' or 'shall not be required'.
NEC Chapter 8 Independence – NEC 90.3 NEC 90.3
Per NEC 90.3, Chapter 8 (Communications Systems) is not subject to the requirements of Chapters 1 through 7 except where those requirements are specifically referenced in Chapter 8.
SI vs. Inch-Pound Compliance – Article 90.9(D) Article 90.9(D)
Per Article 90.9(D), compliance with numbers shown in either the SI (metric) system or the inch-pound system constitutes compliance with the NEC.
Vertically Operated Switch Handle – NEC 404.7 NEC 404.7
Per NEC 404.7, where switch or circuit breaker handles are operated vertically, the up position shall be the closed (on) position.
Elevator Raceway Fill – Article 620.33 Article 620.33
Per NEC Article 620.33, the sum of the cross-sectional area of individual conductors in elevator raceways shall not exceed 50% of the interior cross-sectional area of the raceway.
Minimum Cover – Underground Direct Burial (NEC Table 300.5(A)) NEC Table 300.5(A)
Per NEC Table 300.5(A), direct-buried cables in general locations require a minimum cover of 600 mm (24 in.), while rigid metal conduit or IMC requires only 150 mm (6 in.).
Steel Plate Protection – NEC 300.4(A)(2) NEC 300.4(A)(2)
Per NEC 300.4(A)(2), cables or raceways in notches in wood members must be protected by a steel plate at least 1.6 mm (1/16 in.) thick to prevent nail or screw penetration.
Minimum Service Rating – One-Family Dwelling (NEC 230.79(C)) NEC 230.79(C)
Per NEC 230.79(C), the service disconnecting means for a one-family dwelling shall have a rating of not less than 100 amperes, 3-wire.
Overhead Service Clearance over Public Streets – NEC 230.24(B) NEC 230.24(B)
Per NEC 230.24(B), overhead service conductors not exceeding 1000 V nominal must maintain a minimum clearance of 5.5 m (18 ft) over public streets and alleys.
Ampacity Derating – 7–9 Conductors (NEC Table 310.15(C)(1)) NEC Table 310.15(C)(1)
Per NEC Table 310.15(C)(1), when 7–9 current-carrying conductors are installed in a raceway or cable, the ampacity adjustment factor is 70%.
Minimum Copper Conductor Size – NEC 310.3(A) NEC 310.3(A)
Per NEC 310.3(A), the minimum conductor size for general wiring rated up to 2000 volts is 14 AWG copper or 12 AWG aluminum/copper-clad aluminum.
Ferrous Metal Enclosure Grouping – NEC 300.20(A) NEC 300.20(A)
Per NEC 300.20(A), AC conductors in ferrous metal enclosures must have all phase conductors, grounded conductors, and equipment grounding conductors grouped together to prevent inductive heating.
High-Leg (B Phase) Voltage Ugly's Electrical References, Common Electrical Distribution Systems
In a 120/240 V three-phase four-wire delta high-leg system, the B phase (orange conductor) measures 208 volts to the grounded neutral conductor.

Formulas to Know

Ohm's Law – CurrentI = E ÷ R
Ohm's Law – VoltageE = I × R
Ohm's Law – ResistanceR = E ÷ I
Power Formula (Watt's Law) – PowerP = E × I
Power Formula – Current from Watts and VoltsI = P ÷ E
Series Circuit – Total ResistanceRT = R1 + R2 + R3 + ...
Series Circuit – Current EqualityIT = I1 = I2 = I3
Continuous Load Feeder Minimum AmpacityMinimum Ampacity = Noncontinuous Load + (1.25 × Continuous Load)
Ampacity Derating – Multiple Conductors in RacewayDerated Ampacity = Table Ampacity × Adjustment Factor (e.g., 0.70 for 7–9 conductors)
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