Exam Cheat Sheet · Quick Reference
ICC G18 Residential Electrician Exam (2017 NEC)
National · Pearson Vue
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
60
Passing score
70%
Exam time
180 min
Administered by
Pearson Vue
Format
Reference materials allowed
National State Portion 60 questions
General Knowledge
7 Q · 12%
Electrical Theory and General Electrical Load CalculationsCode Definitions and TermsNEC Purpose, Scope, and Code ArrangementEquipment Approval, Listing, and Labeling RequirementsGeneral Installation Requirements (Article 110)Working Space and Clearances Around Electrical EquipmentConductor Materials, Sizes, and Temperature RatingsElectrical Symbols and Wiring DiagramsField Terms Versus NEC TermsUnits of Measurement, Conversions, and Basic Math for Electricians
Services and Service Equipment
13 Q · 22%
Service Load CalculationsService Equipment & Service ConductorsSystem Grounding and BondingService disconnect requirements and ratingsOverhead and underground service conductor installationGrounding electrode system and electrode typesEquipment grounding conductors — types, sizing, and identificationBonding methods at service equipment and piping systemsDemand factors for dwelling unit appliances and cooking equipmentOptional load calculation methods for dwelling units
Feeders
8 Q · 13%
Load CalculationsEquipment GroundingFeeder conductor ampacity and minimum sizing (NEC Article 215)Overcurrent protection for feedersFeeder neutral load calculations and permitted reductionsGround-fault protection of equipment on feeders rated 1000A or moreOutside feeder installation requirements (clearances, wiring methods, disconnecting means)Demand factors for dwelling unit appliance loads (dryers, ranges, cooking equipment)Feeder conductor identification (grounded, ungrounded, and equipment grounding conductors)
Branch Circuits and Conductors
15 Q · 25%
Branch Circuit CalculationsRequired Outlets & GFCI/AFCI ProtectionOvercurrent ProtectionEquipment GroundingConductorsVoltage Drop Calculations and Conductor SizingConductor Ampacity Tables and Temperature RatingsAmpacity Correction and Adjustment FactorsConductor Insulation Types and ApplicationsGrounded Conductor Identification and UseMultiwire Branch CircuitsBranch-Circuit Voltage Limitations
Wiring Methods and Materials
8 Q · 13%
Raceway InstallationsBoxes and EnclosuresFlexible Cords and CablesCable Wiring Methods (NM, MC, SE, UF, and Type UF underground installations)Conductor Protection Against Physical Damage (nail plates, clearances, framing members)Underground Installation Requirements and Burial DepthsConduit Fill Calculations and Conductor Count LimitsConduit Bending Techniques (90° stubs, offsets, saddle bends, back-to-back)Securing and Supporting Requirements for Cables and RacewaysCorrosion Protection for Raceways and EnclosuresProtection of Conductors in Vertical Raceways
Equipment and Devices
5 Q · 8%
LuminairesReceptacles, Switches and Other DevicesAppliances and Other EquipmentLuminaire location requirements (wet, damp, closets, bathtub/shower zones)Recessed luminaire installation (Type IC vs. non-IC, thermal protection, clearances)Lighting track installation and construction requirementsLow-voltage lighting system requirements (Article 411)Switch ratings, types, and installation requirementsNEMA receptacle and attachment plug configurationsDisconnecting means for appliancesGFCI protection requirements for appliances
Special Occupancies, Equipment, and Conditions
4 Q · 7%
Swimming Pools and Similar InstallationsLow Voltage Circuits, Alarm & Similar SystemsFire Alarm Circuit Classifications (NPLFA vs. PLFA) and Power Source RequirementsFire Alarm Cable Types and Installation by Location (FPLP, FPLR, FPL, NPLFP, NPLFR, NPLF)Class 1, Class 2, and Class 3 Circuit Definitions and Power Source LimitationsSeparation and Mixing Rules for Class 2/3 Circuits with Other Circuit TypesCommunications Circuit Wiring Methods, Cable Types (CMP, CMR, CM, CMX), and Installation by LocationPrimary Protector Requirements and Grounding/Bonding for Communications SystemsRadio and Television Antenna Systems: Grounding, Clearances, and Discharge Units
Key Distinctions
Main bonding jumpervsSystem bonding jumper
The main bonding jumper connects the grounded circuit conductor to the equipment grounding conductor at the service, while a system bonding jumper serves the same function at a separately derived system rather than at the service.
NEC 2017 Article 100 (Definition: Bonding Jumper, Main)Continuous loadvsNoncontinuous load
A continuous load is one whose maximum current is expected to continue for 3 hours or more and is taken at 125% for sizing conductors/overcurrent devices, while noncontinuous load is added at 100%.
NEC 2017 Article 100 — Continuous Load definitionSeries circuitvsParallel resistors
In a series circuit the total current equals the current in any other part of the circuit and resistances add, while resistors in parallel combine as (R1×R2)/(R1+R2) (two equal resistors give R/2).
Ugly's Electrical References, 2023 ed., Series Circuits, Page 3 (2020 ed.: Series Circuits)Single-phase voltage drop formulavsThree-phase voltage drop formula
Single-phase uses the factor 2 (round-trip distance) in Vd = (2K × L × I) ÷ Cm, while three-phase circuits use 1.73 in place of the 2.
Ugly's Electrical References 2020, Voltage Drop CalculationsGrounded (neutral) conductor identificationvsUngrounded conductors in a 120/240-V, single-phase, three-wire system
The grounded neutral is white or gray (an insulated grounded conductor 6 AWG or smaller uses a continuous white or gray outer finish or three white/gray stripes on other than green insulation), while the two ungrounded line conductors are black (line one) and red (line two).
Ugly's Electrical References, 2023 ed., Common Electrical Distribution Systems, Page 13 (2020 ed.: Common Electrical Distribution Systems)120/240-V, single-phase, three-wire systemvs120/240-V, three-phase, four-wire delta high-leg system
The single-phase three-wire system uses black and red ungrounded conductors with a white/gray neutral, whereas the delta high-leg system has a B phase (high leg) that must be colored orange or tagged, with caution noted for 208 volts orange to white.
Ugly's Electrical References, 2023 ed., Common Electrical Distribution Systems, Page 13 (2020 ed.: Common Electrical Distribution Systems)Class 1 remote-control and signaling circuits (Article 725)vsLow-voltage lighting systems (Article 411)
Class 1 circuits are not permitted to exceed 600 volts, while Article 411 low-voltage lighting systems operate at no more than 30 volts ac or 60 volts dc and their secondary circuits shall not be grounded.
NEC 2017 Section 725.41(B)Non-power-limited fire alarm circuitvsPower-limited fire alarm circuit
Article 760 classifies every fire alarm circuit as either non–power-limited or power-limited, and that classification determines which installation requirements apply.
NEC 2017 Section 760.2 (Fire Alarm Circuit)Outdoor overhead span up to 50 ft (1000 volts or less)vsOutdoor overhead span longer than 50 ft (1000 volts or less)
Per 225.6(A)(1), open individual conductors must be not smaller than 10 AWG copper for spans up to 50 ft, but not smaller than 8 AWG copper for longer spans unless supported by a messenger wire.
NEC 2017 Section 225.6(A)Tap conductorvsService conductor
A tap conductor is defined by 240.2 as a conductor OTHER than a service conductor that has overcurrent protection ahead of its point of supply exceeding the value permitted for similar conductors protected per 240.4.
NEC 2017 Section 240.2Ambient correction factor at 40°C for 75°C conductorsvsAmbient correction factor at 40°C for 90°C conductors
At 40°C (104°F) ambient the correction factor is 0.88 for 75°C-rated conductors, but 0.91 for 90°C-rated conductors in the 36–40°C range.
NEC 2017 Table 310.15(B)(2)(a)Using the 90°C column for deratingvs75°C terminal rating limit (110.14(C))
Derating factors may be applied to the higher 90°C ampacity (e.g., 1/0 AWG THHN copper at 170 A × 0.91 = 154.7 A), but the final ampacity used cannot exceed the 75°C terminal rating of that conductor (150 A for 1/0).
NEC 2017 Table 310.15(B)(2)(a) and Section 110.14(C)Objectionable current under 250.6vsNoise/data-error currents in electronic equipment
Currents that introduce noise or data errors in electronic equipment shall NOT be considered the objectionable currents addressed in 250.6, so they do not justify the alterations permitted by 250.6(B).
NEC 2017 Section 250.6(D)Key Terms
Continuous load (Article 100) NEC 2017 Article 100 — Continuous Load definition
A load where the maximum current is expected to continue for 3 hours or more.
Main bonding jumper (Article 100) NEC 2017 Article 100 (Definition: Bonding Jumper, Main)
The connection between the grounded circuit conductor and the equipment grounding conductor at the service.
Tap conductor (240.2) NEC 2017 Section 240.2
A conductor, other than a service conductor, that has overcurrent protection ahead of its point of supply exceeding the value permitted for similar conductors protected as described elsewhere in 240.4.
Authority having jurisdiction (90.4) NEC 2017 Section 90.4
The enforcement authority responsible for interpreting the Code rules, deciding on approval of equipment and materials, and granting special permission contemplated in the rules.
NEC scope exclusions (90.2) NEC 2017 Section 90.2(B)(1)
The Code does not cover installations in ships, watercraft other than floating buildings, railway rolling stock, aircraft, or automotive vehicles other than mobile homes and recreational vehicles.
Fire alarm circuit (Article 760) NEC 2017 Section 760.2 (Fire Alarm Circuit)
A circuit classified as either non–power-limited or power-limited, which determines the applicable installation requirements.
Low-voltage lighting system (411.1, 411.6(A)) NEC 2017 Section 411.1
Lighting systems and associated components operating at no more than 30 volts ac or 60 volts dc, whose secondary circuits shall not be grounded.
Continuity of the grounded conductor (200.2(B)) NEC 2017 Section 200.2(B)
Continuity of a grounded conductor shall not depend on a connection to a metallic enclosure, raceway, or cable armor.
Standard ampere ratings (Table 240.6(A)) NEC 2017 Table 240.6(A)
The listed standard ratings for fuses and inverse time circuit breakers include values such as 45, 70, and 110 amperes; 85 amperes is not a standard rating.
Next higher standard rating rule (240.4(B)) NEC 2017 Section 240.4(B)
The next higher standard overcurrent device rating above conductor ampacity is permitted provided conditions are met, including that the next higher standard rating selected does not exceed 800 amperes and that the conductors are not part of a branch circuit supplying more than one receptacle for cord-and-plug-connected portable loads.
Ground-fault protection of equipment (240.13) NEC 2017 Section 240.13
Required on solidly grounded wye systems of more than 150 volts to ground but not exceeding 1000 volts phase-to-phase for each individual device used as a building or structure main disconnecting means rated 1000 amperes or more.
Coordination for orderly shutdown (240.12) NEC 2017 Section 240.12
Where an orderly shutdown is required to minimize hazards, a system of coordination based on (1) coordinated short-circuit protection and (2) overload indication based on monitoring systems or devices is permitted.
Feeder diagram (215.5) NEC 2017 Section 215.5
If required by the AHJ, a diagram provided before installation showing the area in square feet, total calculated load before demand factors, the demand factors used, the calculated load after demand factors, and the size and type of conductors.
Common neutral for feeders (215.4(A)) NEC 2017 Section 215.4(A)
Up to three sets of 3-wire feeders, or two sets of 4-wire or 5-wire feeders, are permitted to utilize a common neutral.
Receptacle outlet load (220.14(I)) NEC 2017 Section 220.14(I)
Receptacle outlets are calculated at not less than 180 volt-amperes for each single or each multiple receptacle on one yoke, and a single piece of equipment with a multiple receptacle of four or more receptacles is calculated at not less than 90 volt-amperes per receptacle.
Heavy-duty lampholder outlet (220.14(E)) NEC 2017 Section 220.14(E)
Outlets for heavy-duty lampholders shall be calculated at a minimum of 600 volt-amperes.
Service conductors passing through a building (230.3) NEC 2017 Section 230.3
Service conductors supplying a building or other structure shall not pass through the interior of another building or other structure.
Cabinet installation limits (312.2, 312.3, 312.4) NEC 2017 Section 312.3
In walls of concrete, tile, or other noncombustible material the front edge of a cabinet shall not be set back of the finished surface more than ¼ in.; surface-type enclosures in damp or wet locations need at least ¼ in. airspace from the supporting surface (exception: nonmetallic enclosures may be mounted without airspace on concrete, masonry, tile, or similar surfaces); and broken noncombustible surfaces shall be repaired with no gaps greater than 1/8 in. at the edge of a cabinet or cutout box with a flush-type cover.
Raceway limits: RMC, ENT, LFMC, FMC, PVC NEC 2017 Section 344.26
RMC is limited to trade size 6 with not more than four quarter bends (360 degrees total) between pull points; ENT larger than trade size 2½ shall not be used; LFMC must be securely fastened within 12 in. of each box, cabinet, conduit body, or other termination; FMC used where flexibility is needed to minimize vibration or allow movement requires an equipment grounding conductor; and PVC expansion fittings are required where the expected length change is ¼ in. or greater in a straight run between securely mounted items.
Grounding electrode conductor cap for rod, pipe, or plate electrodes (250.66(A)) NEC 2017 Section 250.66(A)
Where the grounding electrode conductor is connected to single or multiple rod, pipe, or plate electrodes and does not extend to other electrode types requiring a larger conductor, it is not required to be larger than 6 AWG copper.
Supplemental electrode spacing (250.53(A)(3)) NEC 2017 Section 250.53(A)(3)
Where multiple rod, pipe, or plate electrodes are installed to meet this section, they shall not be less than 6 ft (1.8 m) apart.
Storable pool cord-connected filter pump GFCI (680.31) NEC 2017 Section 680.31
A cord-connected pool filter pump must have GFCI protection integral to the attachment plug or located in the power-supply cord within 12 in. of the attachment plug.
Formulas to Know
Ohm's Law and power
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); P = E × I (120 V × 5 A = 600 W; 120 V × 12.5 A = 1500 W); P = E² ÷ R (240² ÷ 20 = 2880 W); R = E² ÷ P (14,400 ÷ 1200 = 12 Ω)Voltage drop, single-phase (inductance negligible)
Vd = (2K × L × I) ÷ Cm, where K = 12.9 for copper at 75°C, L = one-way length in feet, I = amperes, Cm = circular mils; three-phase uses 1.73 in place of 2. Example: (2 × 12.9 × 150 × 30) ÷ 16,510 ≈ 7 volts for #8 THWN copper.Percent voltage drop
%VD = Voltage Drop ÷ Source Voltage × 100; example: 7 V ÷ 240 V = 2.9%. NEC recommends total feeder plus branch-circuit drop not exceed 5%, with 3% recommended on each individually. Since VD is proportional to length, a 20% longer run raises a 3% design to 3.6%, and one standard AWG size up (~26% more circular mils, ~20% less VD) restores it to within 3%.Feeder sized for continuous plus noncontinuous load (215.3 OCPD rating; conductor ampacity per NEC 2026 215.4(A)(1) / NEC 2023 215.2(A)(1))
Minimum rating = noncontinuous load + (125% × continuous load). Examples: 40 A + (1.25 × 80 A) = 140 A OCPD (215.3); (100 A × 125%) + 30 A = 155 A minimum feeder conductor ampacity (NEC 2026 215.4(A)(1); NEC 2023 215.2(A)(1)).Dwelling general lighting plus small appliance and laundry load (Article 220 / Table 220.12)
Total VA = (area in sq ft × 3 VA/sq ft) + (1500 VA × number of small appliance circuits) + (1500 VA × number of laundry circuits). Examples: 2000 sq ft + 2 SA + 1 laundry = 6000 + 3000 + 1500 = 10,500 VA; 1800 sq ft + 3 SA + 2 laundry = 5400 + 4500 + 3000 = 12,900 VA; 2500 sq ft + 3 SA + 1 laundry = 7500 + 4500 + 1500 = 13,500 VA; per unit 1200 sq ft + 2 SA + 1 laundry = 8100 VA, × 4 units = 32,400 VA before demand factors.Ambient temperature correction of ampacity
Corrected ampacity = base (table) ampacity × correction factor, applied where ambient differs from the 30°C (86°F) baseline. Example: 1/0 AWG THHN copper 170 A (90°C) × 0.91 (36–40°C ambient) = 154.7 A, but the result may not exceed the 75°C terminal rating (150 A for 1/0).Ampacity of parallel conductor sets
Total ampacity = per-set ampacity × number of sets; example: 350 kcmil THHN copper at 350 A (90°C column, Table 310.16) × 2 sets = 700 A.Series/parallel resistance combinations
Series: Rt = R1 + R2 + ...; two equal resistors in parallel: R ÷ 2; two unequal in parallel: (R1 × R2) ÷ (R1 + R2). Examples: 7 Ω + (30 Ω ÷ 2) = 22 Ω, with I = E ÷ R = 44 V ÷ 22 Ω = 2 A; (8×8)/(8+8) = 4 Ω plus (20×20)/(20+20) = 10 Ω in series = 14 Ω.Optional dwelling calculation — heat pump with supplemental heat (220.82(C)(3))
Heating load = 100% of heat pump compressor nameplate + 65% of supplemental electric heating where the compressor is not prevented from operating at the same time; example: 5000 VA + (15,000 VA × 0.65) = 14,750 VA.Dwelling service conductor 83% allowance (310.15(B)(7))
For a 3-wire, single-phase dwelling unit service, service conductors are permitted an ampacity of 83% of the service rating; example: a 200-ampere service permits 2/0 AWG THW copper instead of 3/0 AWG.