Exam Cheat Sheet · Quick Reference
ICC R16 Master Electrician Exam (2023 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
100
Passing score
75%
Exam time
300 min
Administered by
Pearson Vue
Format
Reference materials allowed
National State Portion 100 questions
General Knowledge
12 Q · 12%
Electrical Theory and General Electrical Load CalculationsCode Definitions and TermsPlan ReadingAC circuit concepts: impedance, reactance, inductance, and capacitance calculationsPower factor, apparent power (kVA), and power factor correctionKirchhoff's Current and Voltage LawsCommon electrical distribution systems and conductor color codingNEC scope, arrangement, and enforcement (Article 90)Electrical symbols and wiring diagram interpretationUnits of measurement, metric system, and engineering conversionsApplied math for electricians: fractions, equations, trigonometry, and geometric formulas
Services and Service Equipment
16 Q · 16%
Services and Fault CurrentService Load CalculationsService Equipment & Service ConductorsTransformersSystem Grounding and BondingTemporary Service WiringOverhead and underground service conductor requirements and clearancesService disconnecting means requirements and ratingsGround-fault protection of equipment at servicesSurge-protective devices (SPDs) at service equipmentGrounding electrode types, installation, and system requirementsEquipment grounding conductor types, sizing, and identification
+2 more
Feeders
4 Q · 4%
Load CalculationsEquipment GroundingMinimum feeder conductor ampacity and sizing (Article 215.2)Feeder overcurrent protection requirements (Article 215.3)Ground-fault protection of equipment for feeders (Article 215.10)Feeder conductor identification — grounded, ungrounded, and EGC (Article 215.12)Surge-protective device requirements for feeders (Articles 215.18 and 225.42)Outside feeder disconnecting means — location, rating, and number (Article 225.31–225.39)Feeder neutral load calculations and permitted reductions (Article 220.61)Common neutral conductors and feeders with shared neutral (Article 215.4)
Branch Circuits and Conductors
16 Q · 16%
Branch Circuit CalculationOvercurrent ProtectionConductorsRequired Outlets & GFCI/AFCI ProtectionEquipment GroundingVoltage Drop Calculations (Single-Phase and Three-Phase)Ampacity Correction and Adjustment Factors (Temperature and Conductor Count)Conductor Insulation Types, Temperature Ratings, and Permitted UsesMultiwire Branch Circuit RequirementsBranch Circuit Voltage Limitations and Permissible LoadsGrounded Conductor Identification and UseGrounding Electrode System and Electrode Types
+1 more
Wiring Methods and Materials
19 Q · 19%
Raceway InstallationsUnderground Wiring MethodsBoxes and EnclosuresCabinets, Panelboards, & SwitchboardsClearance and GuardingFlexible Cords and CablesCable Wiring Methods (NM, MC, AC, MI, SE, UF, TC, ITC, FC, FCC, IGS, Type P)Conductor Fill and Conduit Sizing CalculationsConduit Bending Techniques and CalculationsProtection of Cables and Raceways Against Physical DamageGeneral Wiring Requirements for Conductors of the Same Circuit and Different SystemsCable Tray Systems
+2 more
Equipment and Devices
10 Q · 10%
LuminairesReceptacles, Switches and Other DevicesAppliances and Other EquipmentOther Utilization EquipmentHeating and Cooling EquipmentFixture Wire Types, Ampacities, and Minimum Size RequirementsLuminaire Installation in Specific Locations (wet, damp, closets, bathtub/shower zones)Recessed Luminaire Clearances, Thermal Protection, and Type IC RequirementsLighting Track Installation Requirements and RestrictionsLow-Voltage Lighting System Voltage Limitations and Secondary Circuit RequirementsNEMA Receptacle Configurations and Wiring DiagramsDisconnecting Means for Fixed Electric Space-Heating and Industrial Process Heating Equipment
+1 more
Control Devices
3 Q · 3%
Switches, Disconnects and ControllersMotor Controller Ratings and MarkingsMotor Control Circuit Overcurrent Protection and WiringMotor Disconnecting Means RequirementsMotor Overload Protection Devices and SettingsMotor Control Centers Installation and Overcurrent ProtectionStop-Start and Jogging Control Circuit ConfigurationsIndustrial Control Panel Requirements and MarkingsClass 1, Class 2, and Class 4 Power-Limited Remote-Control Circuits
Motors and Generators
8 Q · 8%
MotorsGeneratorsMotor branch-circuit conductor sizing and ampacityMotor overload protection requirements and ratingsMotor branch-circuit short-circuit and ground-fault protective device ratingsMotor disconnecting means requirements and ratingsMotor controllers: ratings, types, and marking requirementsMotor control circuits and motor control centersGenerator installation, marking, overcurrent protection, and disconnecting meansPhase converters and capacitors in motor circuits
Special Occupancies, Equipment, and Conditions
12 Q · 12%
Special OccupanciesSwimming Pools and Similar InstallationsMobile Home and RV ParksData Processing EquipmentMiscellaneous Special EquipmentEmergency SystemsSignaling and Fire Alarm SystemsHazardous Location Classification (Classes, Divisions, and Zones)Wiring Methods and Equipment for Hazardous LocationsIntrinsically Safe Systems and Associated ApparatusHealth Care Facility Wiring, Grounding, and Essential Electrical SystemsSolar PV, Wind, Fuel Cell, and Energy Storage Systems
+3 more
Key Distinctions
Mandatory rules (NEC)vsPermissive rules (NEC)
Mandatory rules are characterized by the terms 'shall' or 'shall not' (90.5(A)), while permissive rules use 'shall be permitted' or 'shall not be required' (90.5(B)).
NEC 90.5(A) and 90.5(B)Series circuit currentvsParallel circuit current
In a series circuit the total current equals the current in any other part of the circuit (IT = I1 = I2 = I3), whereas in a parallel circuit the total current equals the sum of the branch currents.
Series CircuitsStraight pull box sizing (314.28(A)(1))vsAngle or U pull box sizing (314.28(A)(2))
Straight pulls require box length of at least 8 times the trade size of the largest raceway, while angle/U pulls require at least 6 times the largest raceway trade size plus the sum of the diameters of all other raceway entries in the same row on the same wall.
NEC 314.28(A)(1)Direct-buried cable minimum covervsRMC/IMC minimum cover
In 'all locations not specified' in Table 300.5(A), direct-buried cables or conductors require 600 mm (24 in.) of cover while rigid metal conduit or intermediate metal conduit requires only 150 mm (6 in.).
NEC Table 300.5(A)Cover under a one- and two-family dwelling drivewayvsCover under general streets, roads, alleys and parking lots
Under one- and two-family dwelling driveways/outdoor parking used only for dwelling purposes the minimum cover is 450 mm (18 in.) for both direct-burial cable and RMC, while under general streets, highways, roads, alleys, driveways and parking lots it is 600 mm (24 in.) for all wiring methods.
NEC Table 300.5(A)Elevator raceway conductor fill (620.33)vsGeneral Chapter 9, Table 1 fill
Elevator installations use a special provision limiting the sum of conductor cross-sectional areas to 50 percent of the raceway interior area, which differs from the standard Chapter 9, Table 1 fill percentages used for general wiring.
Article 620.33Motor control circuit tapped from load side of the motor branch-circuit protective devicevsMotor control circuit supplied from a separate source
A tapped control circuit is protected per 430.72, while a control circuit other than such a tapped circuit must be protected per 724.43 (Class 1 power-limited rules) or the notes to Chapter 9 Tables 11(A) and 11(B), as applicable.
NEC, Section 430.72(A)Grounded (neutral) conductor identificationvsUngrounded conductor identification
In a 120/240-volt single-phase, three-wire system the grounded neutral is white or gray (200.6(A)), while the ungrounded conductors are black (line one) and red (line two).
Ugly's Electrical References, Common Electrical Distribution SystemsStandard ampere ratings for fusesvsStandard ampere ratings for inverse time circuit breakers
Table 240.6(A) ratings apply to both, but 1, 3, 6, and 601 amperes are additional standard ratings for fuses only — 601 A is not a standard circuit breaker rating.
NEC 2023, Section 240.6(A) and Table 240.6(A)Ampacity adjustment for 4–6 current-carrying conductorsvsAdjustment for 7–9 and 10–20 current-carrying conductors
Per Table 310.15(C)(1) the factor is 80% for 4–6 conductors, 70% for 7–9 conductors, and 50% for 10–20 conductors.
NEC Table 310.15(C)(1)Motor branch-circuit conductor sizing (430.22)vsMotor feeder conductor sizing (430.24)
Branch-circuit conductors are sized at 125% of the single motor's full-load current, while feeder conductors are sized at 125% of the largest motor's FLC plus the sum of the full-load currents of all other motors.
NEC 430.22, Table 430.248Hermetic motor-compressor conductor sizing (440.32)vsHermetic motor-compressor OCPD sizing (440.22(A))
Branch-circuit conductors must be at least 125% of the rated-load current, while the branch-circuit protective device must not exceed 175% of RLA (next higher standard size permitted by Exception No. 1; up to 225% of RLA only if needed to carry starting current per Exception No. 2).
Key Terms
Authority Having Jurisdiction (AHJ) Article 90.4(B)
Per 90.4, the authority having jurisdiction for enforcement of the Code is responsible for interpreting the rules, deciding on approval of equipment and materials, and granting special permission.
Purpose of the NEC NEC 90.1(A)
Per 90.1(A), the Code's purpose is the practical safeguarding of persons and property from hazards arising from the use of electricity; it is not intended as a design specification or instruction manual for untrained persons.
NEC arrangement NEC 90.3
Per 90.3, the Code 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.
Installations not covered by the NEC Article 90.2(D)
Per Article 90.2, 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.
Array boundary (PV rapid shutdown) Article 690.12(B)
Per 690.12(B)(2), the array boundary is defined as 305 mm (1 ft) from the array in all directions for rapid shutdown purposes.
Main bonding jumper / system bonding jumper as a screw NEC 250.28(B)
Per 250.28(B), if the bonding jumper is a screw only, the screw shall be identified with a green finish visible with the screw installed.
Free conductor length at outlets NEC 300.14
Per 300.14, at least 150 mm (6 in.) of free conductor, measured from where it emerges from the raceway or cable sheath in the box, must be left at each outlet, junction, and switch point.
Device (yoke/strap) box fill allowance NEC 314.16(B)(4)
Per 314.16(B)(4), each yoke or strap containing one or more devices or equipment requires a double volume allowance from Table 314.16(B)(1) based on the largest conductor connected to that yoke or strap.
Field-installed drainage openings (damp/wet locations) NEC 314.15
Per 314.15, approved drainage openings not smaller than 3 mm (1/8 in.) and not larger than 6 mm (1/4 in.) in diameter are permitted to be installed in the field in boxes or conduit bodies listed for damp or wet locations.
Optional calculation for a dwelling unit NEC 2023, Section 220.82(A)
Per 220.82(A), the optional method applies to a dwelling unit whose total connected load is served by a single 120/240-volt or 208Y/120-volt set of 3-wire service or feeder conductors with an ampacity of 100 or greater.
Table 310.16 ampacity basis NEC 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).
Type THHN conductor temperature rating NEC Table 310.4(1)
Per Table 310.4(1), Type THHN has a maximum operating temperature of 90°C (194°F) in dry and damp locations.
Stranded conductors in raceways NEC 310.3(C)
Per 310.3(C), conductors 8 AWG and larger installed in raceways shall be stranded unless specifically permitted or required elsewhere in the Code to be solid.
Minimum service disconnect rating, one-family dwelling NEC 230.79(C)
Per 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 conductors NEC 230.23(B)
Per 230.23(B) they shall not be smaller than 8 AWG copper or 6 AWG aluminum/copper-clad aluminum; per 230.24(B) they must clear public streets, alleys, roads, truck-traffic parking areas, nonresidential driveways and cultivated/grazing/forest/orchard land by at least 5.5 m (18 ft) at not over 1000 volts nominal; per 230.10 vegetation such as trees shall not be used for their support.
Protection from nails and screws (300.4) NEC 300.4(A)(1)
Bored holes in wood members must keep the hole edge at least 32 mm (1 1/4 in.) from the member edge (300.4(A)(1)); cables/raceways parallel to framing members must keep 32 mm (1 1/4 in.) from the edge (300.4(D)); where that distance cannot be maintained, or in notches, a steel plate at least 1.6 mm (1/16 in.) thick covering the wiring area is required (300.4(A)(2)).
Service-entrance cable support NEC 230.51(A)
Per 230.51(A), service-entrance cables shall be supported by straps or other approved means within 300 mm (12 in.) of every service head, gooseneck, or connection to a raceway or enclosure.
Dust entrance prevention, Class II Division 1 (502.15) NEC 502.15
Where a raceway connects a dust-ignitionproof enclosure to one that is not, permitted alternatives to a permanent effective seal include a horizontal raceway at least 3.05 m (10 ft) long, a vertical raceway at least 1.5 m (5 ft) extending downward, or electrical sealing putty.
Formulas to Know
Ohm's law and power relationships
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; P = E² ÷ R ((240)² ÷ 20 = 2880 W); R = E² ÷ P (14,400 ÷ 1200 = 12 Ω)Minimum service-entrance/feeder conductor ampacity with continuous loads
Ampacity ≥ noncontinuous load + (125% × continuous load); e.g., 80 A + (60 A × 1.25) = 155 A, and (100 A × 1.25) + 30 A = 155 AMinimum branch-circuit OCPD rating for continuous loads
OCPD rating ≥ 125% × continuous load; 16 A × 1.25 = 20 A (210.20(A))Three-phase power and current
kW = (E × I × PF × 1.73) ÷ 1000, e.g., (460 × 52 × 0.80 × 1.73) ÷ 1000 ≈ 33 kW; I = (kW × 1000) ÷ (E × PF × 1.73); 1.73 ≈ √3Pull/junction box minimum dimensions (conductors 4 AWG and larger)
Straight pull: length ≥ 8 × trade size of largest raceway (8 × 3 in. = 24 in.). Angle/U pull: raceway entry to opposite wall ≥ 6 × trade size of largest raceway plus sum of diameters of other raceway entries in the same row (6 × 3 = 18 + 2 = 20 in.)Box fill volume allowances
14 AWG = 32.8 cm³ (2.00 in.³) each; 12 AWG = 36.9 cm³ (2.25 in.³) each; each yoke/strap with device(s) = double the allowance for the largest conductor connected to it; a 4 × 1¼ in. round/octagonal box (12.5 in.³) permits a maximum of five 12 AWG conductors per Table 314.16(A)Motor branch-circuit and feeder sizing
Branch-circuit conductors ≥ 125% × motor FLC from Table 430.248/430.250 (28 A × 1.25 = 35 A; 65 A × 1.25 = 81.25 A). Feeder ≥ (125% × largest motor FLC) + sum of other motor FLCs ((1.25 × 65) + 40 = 121.25 A). Nontime delay fuse for AC polyphase motor = 300% of FLC (3.00 × 65 = 195 A), next standard size (200 A) permitted per 430.52(C)(1) Exception No. 1Hermetic refrigerant motor-compressor sizing
Conductors ≥ 125% × RLA (30 A × 1.25 = 37.5 A; 20 A × 1.25 = 25 A) per 440.32; OCPD ≤ 175% × RLA (30 A × 1.75 = 52.5 A → next standard 60 A; 20 A × 1.75 = 35 A) per 440.22(A), increased to a maximum of 225% of RLA only if needed for starting currentNon-dwelling lighting and receptacle load calculations
Retail lighting: area (sq ft) × 1.9 VA/sq ft (5000 × 1.9 = 9500 VA; the 125% continuous multiplier is already included per the note to Table 220.42(A)). Receptacles: 180 VA per single or multiple receptacle on one yoke (220.14(I)). Non-dwelling receptacle demand (Table 220.47): first 10 kVA at 100% + remainder at 50% (10,000 + 0.50 × 8000 = 14,000 VA)Parallel conductors, tap conductors, and elevator feeder demand
Parallel ampacity = per-set ampacity × number of sets (350 kcmil Cu at 90°C = 350 A; 2 sets = 700 A); grounded conductor sized from total parallel kcmil (2 × 350 = 700 kcmil → 2/0 AWG Cu per Table 250.102(C)(1)); 10-ft feeder tap leaving the enclosure ≥ 1/10 of feeder OCPD rating (200 A ÷ 10 = 20 A) per 240.21(B)(1); elevator feeder demand factor for 5 elevators = 0.82 (Table 620.14)