Exam Cheat Sheet · Quick Reference
Idaho Limited Electrical Limited Energy Installer
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
40
Passing score
70%
Exam time
120 min
Administered by
PSI Services Contractor
Format
Reference materials allowed
Idaho State Portion 40 questions
2017 National Electrical Code, NFPA – Introduction
6 Q · 15%
Purpose and scope of the NEC (practical safeguarding of persons and property)Installations covered and not covered by the NEC (90.2)Code arrangement and chapter organization (90.3)Authority having jurisdiction (AHJ) roles and enforcement (90.4)Mandatory vs. permissive rules and explanatory material (90.5)Equipment examination, listing, and approval for safety (90.7)Wiring planning for future expansion and circuit limitations (90.8)Units of measurement and SI vs. inch-pound compliance (90.9)
2017 National Electrical Code, NFPA – Chapter 1
4 Q · 10%
Key NEC Article 100 definitions (accessible, approved, labeled, listed, identified)Branch circuit types and definitions (general-purpose, individual, multiwire, appliance)Grounding and bonding terminology (grounded conductor, EGC, grounding electrode, bonding jumper)Equipment approval, listing, and labeling requirements (Article 110.2–110.3)Electrical connections, splices, and termination temperature ratings (Article 110.14)Working space and clearance requirements around electrical equipment (Article 110.26)Guarding of live parts and enclosure type selection (Articles 110.27–110.28)Equipment markings, arc-flash hazard warnings, and disconnecting means identification (Articles 110.16, 110.21–110.22, 110.24)Article 100 - Definitions
2017 National Electrical Code, NFPA – Chapter 2
3 Q · 8%
Grounding and bonding requirements (Article 250) — system grounding, grounding electrode systems, and equipment grounding conductorsBranch circuit requirements — ratings, conductor sizing, GFCI and AFCI protection, and required outlets (Article 210)Overcurrent protection — fuses, circuit breakers, tap conductor rules, and location requirements (Article 240)Branch-circuit, feeder, and service load calculations — dwelling and non-dwelling demand factors and optional calculation methods (Article 220)Use and identification of grounded conductors — color coding, terminal identification, and polarity (Article 200)Grounding electrode types, installation, and sizing of grounding electrode conductorsBonding requirements — service equipment, piping systems, structural metal, and communication systemsEquipment grounding conductor types, sizing, and identificationArticle 250 - Grounding and Bonding
2017 National Electrical Code, NFPA – Chapter 3
8 Q · 20%
Conductor ampacity tables and temperature ratings (Article 310)Ampacity adjustment and correction factors for conductorsProtection of cables and raceways against physical damage (Article 300)Underground wiring installation requirements and minimum cover depthsBox and conduit body fill calculations and sizing (Article 314)Securing and supporting requirements for conduit types (EMT, RMC, PVC, FMC, LFMC, LFNC)Uses permitted and not permitted for wiring methods (NM cable, MC cable, conduit types)Cable tray installation, fill requirements, and ampacity (Article 392)Article 310 - Conductors for General Wiring
2017 National Electrical Code, NFPA – Chapter 7
18 Q · 45%
Class 1, Class 2, and Class 3 circuit definitions and power source requirementsFire alarm circuit types: power-limited (PLFA) and non-power-limited (NPLFA)Cable types, listing requirements, and substitution hierarchy for low-voltage systemsSeparation and installation of conductors in different circuit typesOptical fiber cable types, installation, and grounding requirementsFire-resistive cable systems and circuit integrity (CI) cable requirementsInstrumentation tray cable (Type ITC) uses, installation, and constructionEnergy management systems: load control restrictions and field marking requirementsArticle 725 - Class 1, Class 2, and Class 3 Remote-Control, Signaling, and Power-Limited CircuitsArticle 760 - Fire Alarm SystemsArticle 770 - Optical Fiber Cables
2017 National Electrical Code, NFPA Calculations – Chapter 2
1 Q · 2%
Branch-circuit load calculations using unit lighting loads (Table 220.12)Demand factors for general lighting loads by occupancy type (Table 220.42)Minimum load calculations for receptacle outlets and specific appliances (220.14)Small-appliance and laundry circuit loads for dwelling units (220.52)Feeder and service load calculations for electric ranges and cooking appliances (Table 220.55)Demand factors for electric clothes dryers in dwelling units (Table 220.54)Optional feeder and service load calculations for dwelling units (220.82)Farm load calculations and demand factors (Tables 220.102 and 220.103)
Key Distinctions
NEC Chapters 1, 2, 3, and 4vsNEC Chapters 5, 6, and 7 (and Chapter 8)
Per 90.3, Chapters 1–4 apply generally to all electrical installations, while Chapters 5, 6, and 7 apply to special occupancies, special equipment, or other special conditions and may supplement or modify Chapters 1 through 7; Chapter 8 covers communications systems and is independent except where specifically referenced.
NEC 2017 Section 90.3Chapter 9 tablesvsInformative annexes
Chapter 9 consists of tables that are applicable as referenced elsewhere in the Code and are enforceable when referenced, whereas informative annexes are not part of the Code requirements.
NEC 2017 Section 90.3Mandatory rulesvsInformational notes (explanatory material)
Mandatory rules identify actions specifically required or prohibited and use the terms 'shall' or 'shall not' (90.5(A)), while informational notes are included for informational purposes only and are not enforceable as requirements (90.5(C)).
NEC 2017 Section 90.5(A)Hard conversionvsSoft conversion
Per 90.9(B) conversions to SI must be based on hard conversion (which changes the dimension or property to a new size) except as provided in 90.9(C); soft conversion, a direct mathematical conversion that does not change the actual dimension, is permitted for trade sizes, extracted material, industry practice, and where a negative impact on safety would result (90.9(C)(4)).
NEC 2017 Section 90.9(C)(4)Cables marked by printed tag on coil, reel, or carton (310.120(B)(3))vsCables durably surface marked (310.120(B)(1))
Type MI cable, switchboard wires, metal-covered single-conductor cables, and Type AC cable are tag marked, while nonmetallic-sheathed cable, service-entrance cable, and tray cable are durably surface marked.
NEC 2017 Section 310.120(B)(3)180 volt-amperes per yokevs90 volt-amperes per receptacle
Per 220.14(I), receptacle outlets are calculated at not less than 180 VA for each single or multiple receptacle on one yoke, but a single piece of equipment consisting of a multiple receptacle comprised of four or more receptacles is calculated at not less than 90 VA per receptacle.
NEC 2017 Section 220.14(I)Dwelling, MultifamilyvsTwo-family dwelling
Per Article 100, a multifamily dwelling contains three or more dwelling units, while a building with exactly two units is a two-family dwelling.
NEC 2017 Article 100 — Definition of "Dwelling, Multifamily"SPD Type 1vsSPD Type 2 / Type 3 / Type 4
Per Article 100, a Type 1 SPD is permanently connected between the service transformer secondary and the line side of the service disconnect overcurrent device; Type 2 is permanently connected on the load side of that device, Type 3 is point of utilization, and Type 4 is a component SPD.
NEC 2017 Article 100 — Definition of "Surge-Protective Device (SPD)"THHNvsWet-location conductor types (MTW, RHW, RHW-2, TW, THW, THW-2, THHW, THWN, THWN-2, XHHW, XHHW-2, ZW)
Per 310.10(C), THHN is rated for dry and damp locations only and is not listed for wet locations, while the listed types are permitted in wet locations.
NEC 2017 Section 310.10(C)Type FPLP (power-limited fire alarm plenum cable)vsType NPLFP (non–power-limited fire alarm plenum cable)
PLFA cable in other spaces used for environmental air must be Type FPLP per 760.135(C), while NPLFA cable in those same plenum spaces (not in a compliant raceway) must be Type NPLFP per 760.53(B)(2).
NEC 2017 Section 760.135(C)Opening for equipment above a lay-in ceilingvsAccessible opening in a crawl space
Per 110.26(A)(4)(a), equipment under 1000 volts to ground above a lay-in ceiling requires an opening not smaller than 22 in. × 22 in., whereas the 22 in. × 30 in. dimension applies to an accessible opening in a crawl space.
NEC 2017 Section 110.26(A)(4)(a)AWGvsCircular mils (kcmil)
Per 110.6, conductor sizes are expressed in AWG for conductors up to 4/0 AWG and in circular mils for conductors larger than 4/0 AWG.
NEC 2017 Section 110.6Key Terms
Ampacity (Article 100) NEC 2017
The maximum current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating.
Continuous Load (Article 100) NEC 2017 Article 100
A load where the maximum current is expected to continue for 3 hours or more.
Authority Having Jurisdiction (AHJ) (Article 100; 90.4) NEC 2017 Article 100 (Definitions)
An organization, office, or individual responsible for enforcing the requirements of a code or standard, or for approving equipment, materials, an installation, or a procedure; per 90.4 the AHJ makes interpretations of the rules, decides on approval of equipment and materials, and grants special permission.
Dwelling, Multifamily (Article 100) NEC 2017 Article 100 — Definition of "Dwelling, Multifamily"
A building that contains three or more dwelling units.
Surge-Protective Device (SPD), Type 1 (Article 100) NEC 2017 Article 100 — Definition of "Surge-Protective Device (SPD)"
A permanently connected SPD intended for installation between the secondary of the service transformer and the line side of the service disconnect overcurrent device.
Fire Alarm Circuit (760.2) NEC 2017 Section 760.2 (Fire Alarm Circuit)
A circuit classified as either non–power-limited or power-limited, and that classification determines the applicable installation requirements.
Trade size designator (90.9(C)(1)) NEC 2017 Section 90.9(C)(1)
The designation used in the Code rather than dimensions where the actual measured size of a product is not the same as its nominal size, with trade practices followed in all cases.
Scope of the Code (90.2(A)) NEC 2017
The Code covers the installation and removal of electrical conductors, equipment, and raceways; signaling and communications conductors, equipment, and raceways; and optical fiber cables and raceways for public and private premises, including buildings, structures, mobile homes, recreational vehicles, and floating buildings.
Voltage considered (110.4) NEC 2017 Section 110.4
Throughout the Code the voltage considered shall be that at which the circuit operates, and the voltage rating of electrical equipment shall not be less than the nominal voltage of the circuit to which it is connected.
Class 1 remote-control and signaling circuit (725.41(B); 725.49(A)) NEC 2017 Section 725.41(B)
A circuit that is not permitted to exceed 600 volts and that may use conductors as small as 16 AWG and 18 AWG.
Class 1 circuit physical protection (725.31(B)) NEC 2017 Section 725.31(B)
Where damage to a Class 1 remote-control or signaling circuit would introduce a hazard as covered in 725.31, the circuit is required to have physical protection.
Inherently limited Class 2 power source — dry cell battery (725.121(A)(5)) NEC 2017 Section 725.121(A)(5)
A dry cell battery qualifies when its voltage is 30 volts or less and its capacity is equal to or less than that available from series-connected No. 6 carbon zinc cells.
Type FPLP (760.135(C)) NEC 2017 Section 760.135(C)
Power-limited fire alarm plenum cable required for PLFA circuits installed in other spaces used for environmental air; the 'P' suffix designates plenum-rated cable with adequate fire-resistant and low-smoke-producing characteristics.
Type NPLFP (760.53(B)(2)) NEC 2017 Section 760.53(B)(2)
The plenum-rated non–power-limited fire alarm cable (listed per 760.176(C)) required in other spaces used for environmental air; Types NPLFR and NPLF are permitted there only when installed in compliance with 300.22(C).
Type OFNR substitution (770.154, Table 770.154(b)) NEC 2017 Table 770.154(b)
Type OFNP is the only permitted substitution for Type OFNR nonconductive optical fiber riser cable; conductive types (OFCP, OFCR) may not be substituted and OFNG has a lower fire-resistance rating.
Parallel conductors (310.10(H)(1)) NEC 2017 Section 310.10(H)(1)
Aluminum, copper-clad aluminum, or copper conductors for each phase, polarity, neutral, or grounded circuit are permitted to be connected in parallel (electrically joined at both ends) only in sizes 1/0 AWG and larger.
Formulas to Know
Minimum bending radius, Type MC cable with interlocked-type armor or corrugated sheath (330.24(B))
Minimum inner-edge bend radius = 7 × external diameter of the metallic sheath; worked example: 7 × 1.5 in. = 10.5 in.Overcurrent protection for a Class 1 power-limited circuit source other than a transformer (725.41(A)(2))
OCPD rating shall be not more than 167% × (volt-ampere rating of the source ÷ rated voltage); the device may be integral to the power supply but shall not be interchangeable with devices of higher ratings.General lighting load for dwelling units (Table 220.12)
Minimum unit load = 3 volt-amperes per square foot of floor area.Receptacle outlet branch-circuit load (220.14(I))
Not less than 180 VA for each single or each multiple receptacle on one yoke; for a single piece of equipment that is a multiple receptacle of four or more receptacles, not less than 90 VA per receptacle (show windows are 200 VA per linear foot under 220.14(G)).Watts to kilowatts conversion
kW = watts ÷ 1,000 (kilo = 1,000); example: 2,400 W = 2.4 kW.Next higher standard overcurrent device rating (240.4(B))
The next higher standard OCPD rating above the conductor ampacity may be used provided the next higher standard rating selected does not exceed 800 amperes, and the conductors are not part of a branch circuit supplying more than one receptacle for cord-and-plug-connected portable loads.Small conductor overcurrent protection (240.4(D)(3))
14 AWG copper: overcurrent protection not exceeding 15 amperes.PVC conduit expansion fittings (352.44)
Provide expansion fittings where the expected length change from thermal expansion and contraction is 6 mm (¼ in.) or greater in a straight run between securely mounted items.Maximum bends between pull points, RMC (344.26)
Not more than the equivalent of four quarter bends (360 degrees total) between pull points such as conduit bodies and boxes.EMT support spacing (358.30(A)) and LFMC termination fastening (350.30(A))
EMT: securely fastened at intervals not to exceed 10 ft, and within 3 ft of each outlet box, junction box, device box, cabinet, conduit body, or other tubing termination. LFMC: securely fastened within 12 in. of each box, cabinet, conduit body, or other conduit termination.