Exam Cheat Sheet · Quick Reference
Kansas City, MO Master Electrician Exam (ICC G16, 2017 NEC)
Missouri · 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
Missouri State Portion 100 questions
General Knowledge
12 Q · 12%
Electrical Theory and General Electrical Load CalculationsCode Definitions and TermsPlan ReadingNEC 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 DiagramsUnits of Measurement, Conversions, and Math FundamentalsAC Circuit Properties (Impedance, Reactance, Inductance, Capacitance, Power Factor)
Services and Service Equipment
16 Q · 16%
Services and Fault CurrentService Load CalculationsService Equipment & Service ConductorsTransformersSystem Grounding and BondingTemporary Service WiringService entrance conductor installation methods and clearancesService disconnecting means requirements and ratingsOvercurrent protection for services and transformersGrounding electrode system types and installationEquipment grounding conductor sizing and identificationSurge arresters and surge-protective devices (SPDs)
+1 more
Feeders
4 Q · 4%
Load CalculationsEquipment GroundingFeeder conductor sizing and ampacity requirementsOvercurrent protection for feedersFeeder neutral load calculations and demand factorsOutside feeders: clearances, conductor sizing, and disconnecting meansDemand factors for dwelling and non-dwelling feeder loadsGround-fault protection of equipment for feedersFeeder conductor identification requirements
Branch Circuits and Conductors
16 Q · 16%
Branch Circuit CalculationOvercurrent ProtectionConductorsRequired Outlets & GFCI/AFCI ProtectionEquipment GroundingVoltage Drop Calculations (Single-Phase and Three-Phase)Conductor Insulation Types and Application EnvironmentsAmpacity Correction and Adjustment FactorsGrounded Conductor Identification and UseMultiwire Branch CircuitsBranch-Circuit Voltage Limitations
Wiring Methods and Materials
19 Q · 19%
Raceway InstallationsUnderground Wiring MethodsBoxes and EnclosuresCabinets, Panelboards, & SwitchboardsClearance and GuardingFlexible Cords and CablesCable Wiring Methods (NM, AC, MC, MI, SE, UF, TC, MV, FCC, FC, IGS cable types)Conduit and Tubing Types (RMC, IMC, EMT, FMC, LFMC, PVC, HDPE, RTRC, ENT, LFNC, FMT)Conductor Fill and Conduit Sizing (percent fill, conductor area tables, conduit dimensions)Conduit Bending Methods (90° bends, offsets, saddle bends, back-to-back, multi-shot)Wireways, Auxiliary Gutters, Busways, and Cable TraysGeneral Wiring Requirements (physical protection, conductor grouping, fire spread, temperature limitations)
+2 more
Equipment and Devices
10 Q · 10%
LuminairesReceptacles, Switches and Other DevicesAppliances and Other EquipmentOther Utilization EquipmentHeating and Cooling EquipmentFixture Wire Types, Ampacity, and Installation RequirementsNEMA Receptacle and Plug ConfigurationsLighting Track Installation and Construction RequirementsLow-Voltage Lighting Systems (Article 411)Disconnect Requirements for Fixed Electric Heating EquipmentOvercurrent Protection for Resistance Heating ElementsGround-Fault Protection for Deicing, Snow-Melting, and Pipeline Heating Equipment
+1 more
Control Devices
3 Q · 3%
Switches, Disconnects and ControllersMotor controller ratings and markings (horsepower, voltage, short-circuit current)Motor control circuit overcurrent protection and wiring (Article 430 Part VI)Motor disconnecting means types, location, and ampere ratingsMotor control center construction, overcurrent protection, and groundingClass 1, Class 2, and Class 3 remote-control circuit classifications and power source requirementsStop-start station wiring and control relay circuits (jogging, hand-off-automatic)Industrial control panel overcurrent protection, short-circuit current rating, and disconnecting meansElectronic lighting control switches and dimmer switch ratings (Article 404)
Motors and Generators
8 Q · 8%
MotorsGeneratorsMotor branch-circuit conductor sizing (125% FLC rule)Motor branch-circuit short-circuit and ground-fault protection (Table 430.52)Motor overload protection (sizing and placement of overload devices)Motor disconnecting means (type, location, and rating requirements)Motor controllers (ratings, types, and design requirements)Motor control centers (overcurrent protection, grounding, and busbar requirements)Capacitors in motor circuits (conductor sizing, discharge requirements, and effect on overload device settings)Phase converters (conductor ampacity, overcurrent protection, and disconnecting means)
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 (Classified) Locations — Class I, II, and III Division and Zone ClassificationProtection Techniques for Hazardous Locations (explosionproof, intrinsically safe, dust-ignitionproof, pressurized)Specific Hazardous Occupancies (commercial garages, aircraft hangars, motor fuel dispensing, bulk storage, spray finishing)Health Care Facilities — Essential Electrical Systems and Patient Care WiringStandby and Emergency Power Systems (legally required standby, optional standby, critical operations power systems, fire pumps)
+3 more
Key Distinctions
Main bonding jumpervsSystem bonding jumper
Per NEC Article 100, the main bonding jumper is the connection between the grounded circuit conductor and the equipment grounding conductor at the service, while the system bonding jumper makes that same type of connection (to the supply-side bonding jumper, the equipment grounding conductor, or both) at a separately derived system.
NEC 2017 Article 100 (Definition: Bonding Jumper, Main)Chapter 9, Table 4vsChapter 9, Table 5
Table 4 gives the usable area within the selected conduit or tubing, while Table 5 gives the required area for each individual conductor; both are used together (instead of Informative Annex C) when conductors are of different sizes or insulation types.
NEC 2017 Chapter 9, Table 5Nontime-delay fuse for a single-phase motorvsDual-element (time-delay) fuse for a single-phase motor
Per Table 430.52, the nontime-delay fuse maximum is 300% of full-load current while the dual-element (time-delay) fuse maximum is 175% of full-load current.
Ugly's Electrical References 2020, Page 38Instantaneous trip breaker on a DC constant-voltage motorvsInstantaneous trip breaker on AC polyphase/single-phase motors
Table 430.52 allows a maximum setting of 250% of full-load current for a direct-current constant-voltage motor, significantly lower than the 800% allowed for AC polyphase and single-phase motors.
Ugly's Electrical References 2020, Page 38, Table 430.52Inverse time circuit breaker on a wound rotor motorvsNontime-delay fuse on a single-phase motor
Table 430.52 caps the inverse time breaker for a wound rotor motor at 150% of full-load current, while a nontime-delay fuse on a single-phase motor may be rated up to 300% of full-load current.
Ugly's Electrical References 2020, Page 38Wye-start, delta-run motor conductors (430.22(C))vsPart-winding connected motor conductors (430.22(D))
Conductors between controller and motor shall not be less than 72% of motor full-load current for a wye-start/delta-run motor, but not less than 62.5% (50% × 1.25) for a part-winding connected motor.
NEC 2017 Section 430.22(C)Motor branch-circuit conductor sizingvsMotor feeder conductor sizing
Branch-circuit conductors are sized at 125% of that motor's full-load current (430.22(A)), while feeder conductors are sized at 125% of the largest motor's full-load current plus the sum of the remaining motors' full-load currents.
Ugly's Electrical References 2020, Pages 41-42GEC to rod, pipe, or plate electrode (250.66(A))vsGEC to concrete-encased electrode (250.66(B))
Where it is the sole connection, the grounding electrode conductor is not required to be larger than 6 AWG copper for a rod, pipe, or plate electrode, but is not required to be larger than 4 AWG copper for a concrete-encased electrode.
NEC 2017 Section 250.66(A)Type AC cable bending radius (320.24)vsType MC cable with interlocked armor or corrugated sheath (330.24(B))
Type AC cable bends shall have an inner-edge radius not less than five times the cable diameter, while interlocked-armor/corrugated-sheath Type MC requires seven times the external diameter of the metallic sheath.
NEC 2017 Section 320.24120/240-volt, three-phase, four-wire delta (high leg)vs277/480-volt, three-phase, four-wire wye
The delta high-leg system has a B phase that must be colored orange or tagged (caution: 208 volts orange to white), while in the 277/480V wye system the C phase ungrounded conductor is colored yellow.
Ugly's Electrical References, 2023 ed., Common Electrical Distribution Systems, Page 13 (2020 ed.: Common Electrical Distribution Systems)Three-phase multiplier 1.73vsSingle-phase factor of 2
Three-phase calculations use 1.73 (the square root of 3, reflecting the 120-degree phase relationship) in place of the factor of 2 used in single-phase voltage-drop calculations.
Ugly's Electrical References 2020, Voltage Drop CalculationsCommon neutral with 3-wire feedersvsCommon neutral with 4-wire or 5-wire feeders
Per 215.4(A), up to three sets of 3-wire feeders are permitted to use a common neutral, but only two sets of 4-wire or 5-wire feeders.
NEC 2017 Section 215.4(A)Hermetic compressor OCPD in NEC 2017 and 2020vsHermetic compressor OCPD in NEC 2023 and 2026
With a 175%-of-RLA calculation landing between standard sizes, the 2017 and 2020 editions have no next-size-up exception so the device may not exceed the calculated value, while 2023/2026 (440.22(A) Exception No. 1) permit the next higher standard rating; in all editions the rating may be increased to not more than 225% of RLA if needed to carry starting current.
NEC 2017 Section 440.22(A), 440.32Key Terms
Authority Having Jurisdiction (AHJ) NEC 2017 Article 100 (Definitions)
Per NEC Article 100, 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 for enforcement has responsibility for interpreting the rules, deciding on approval of equipment and materials, and granting special permission.
Continuous load NEC 2017 Article 100 — Continuous Load definition
Per NEC Article 100, a load where the maximum current is expected to continue for 3 hours or more, which typically requires conductors and devices rated at 125% of the continuous load current.
Bonding jumper, main NEC 2017 Article 100 (Definition: Bonding Jumper, Main)
Per NEC Article 100, the connection between the grounded circuit conductor and the equipment grounding conductor at the service; without it the effective ground-fault current path at the service is incomplete.
Bonding jumper, system NEC 2017 Article 100 (Definition: Bonding Jumper, System)
Per NEC Article 100, the connection between the grounded circuit conductor and the supply-side bonding jumper, the equipment grounding conductor, or both, at a separately derived system.
Tap conductor NEC 2017 Section 240.2
Per NEC 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.
Pull point (EMT bend limit) NEC 2017 Section 358.26
A conduit body or other pull point divides an EMT run so that each section between pull points may contain up to 360 degrees of bends (NEC 2017/2020: 358.26; NEC 2023/2026: 358.24(B)).
Objectionable current (250.6(D)) NEC 2017 Section 250.6(D)
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).
Grounded conductor identification, 6 AWG or smaller (200.6(A)) NEC 2017 Section 200.6(A)
An insulated grounded conductor 6 AWG or smaller shall be identified by a continuous white outer finish, a continuous gray outer finish, or three continuous white or gray stripes along its entire length on other than green insulation.
Continuity of the grounded conductor (200.2(B)) NEC 2017 Section 200.2(B)
The continuity of a grounded conductor shall not depend on a connection to a metallic enclosure, raceway, or cable armor.
Type IGS (Integrated Gas Spacer) cable NEC 2017 Section 326.104
Per 326.104, its conductors shall be solid aluminum rods laid parallel, consisting of one to nineteen 12.7 mm (½ in.) diameter rods, with a minimum conductor size of 250 kcmil and a maximum of 4750 kcmil.
Class 1 remote-control and signaling circuit NEC 2017 Section 725.41(B)
Per Article 725 commentary (725.41(B)), Class 1 circuits are not permitted to exceed 600 volts.
Low-voltage lighting secondary circuit (411.6(A)) NEC 2017 Section 411.6(A)
Secondary circuits of low-voltage lighting systems covered by Article 411 shall not be grounded.
NEC scope exclusions (90.2(B)(1)) 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.
Industrial control panel with single main OCPD inside (409.21(B)) NEC 2017 Section 409.21(B)
Where the required overcurrent protection for each incoming supply circuit is a single main overcurrent protective device located within the industrial control panel, the supply conductors are considered either feeders or taps as covered by 240.21.
Weather-resistant receptacle in a damp location (406.9(A)) NEC 2017 Section 406.9(A)
A receptacle in a damp location (such as under a roofed open porch or covered patio not subjected to beating rain) shall have an enclosure that is weatherproof when the receptacle is covered, and all 15- and 20-ampere, 125- and 250-volt nonlocking receptacles there shall be a listed weather-resistant type.
Standard ampere ratings (Table 240.6(A)) NEC 2017 Table 240.6(A)
The table of standard ampere ratings for fuses and inverse time circuit breakers includes ratings such as 45, 70, and 110 amperes; 85 amperes is not a standard rating.
Residential service conductor allowance (310.15(B)(7)) NEC 2017 Section 310.15(B)(7) with Table 310.15(B)(16)
For a 3-wire, single-phase dwelling unit service, service conductors are permitted to have an ampacity of 83% of the service rating — for example, 2/0 AWG THW copper for a 200-ampere service instead of 3/0 AWG.
Formulas to Know
Ohm's Law and power formulas (single-phase/DC basics)
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 V)² ÷ 20 Ω = 2880 W; (120 V)² ÷ 12 Ω = 1200 W); R = E² ÷ P (14,400 ÷ 1200 = 12 Ω)Three-phase kilowatts and amperes (1.73 = √3)
KW = (E × I × PF × 1.73) ÷ 1000 — e.g., (460 V × 52 A × 0.80 × 1.73) ÷ 1000 ≈ 33 kW; I = (KW × 1000) ÷ (E × PF × 1.73)Three-phase voltage drop (inductance negligible)
Vd = (1.73 × K × L × I) ÷ Cm, where 1.73 replaces the factor of 2 used in single-phase calculationsFeeder with continuous and noncontinuous loads
Conductor ampacity (215.2(A)(1)(a)): not less than noncontinuous + 125% of continuous — e.g., 120 A + (80 A × 1.25) = 220 A. Overcurrent device rating (215.3): not less than noncontinuous + 125% of continuous — e.g., 40 A + (80 A × 1.25) = 140 A.Motor branch-circuit conductor ampacity (430.22(A))
125% × motor full-load current — e.g., 50 HP, 480 V, 3-phase at 65 A FLC: 1.25 × 65 = 81.25 AMotor feeder conductor sizing (general motor rules)
125% of the largest motor's full-load current plus the sum of the remaining motors' full-load currentsMotor branch-circuit short-circuit/ground-fault device sizing with next standard size
Percentage from Table 430.52 × FLC; where the result is not a standard size, 430.52(C)(1) Exception No. 1 permits the next standard size from Table 240.6(A) — e.g., nontime-delay fuse 300% × 65 A = 195 A → 200-ampere fuseGenerator conductor ampacity (445.13)
Conductors from generator output terminals to the first overcurrent device: ampacity not less than 115% of nameplate current — 80 A × 1.15 = 92 A; 200 A × 1.15 = 230 AHermetic refrigerant motor-compressor branch circuit (440.32 / 440.22(A))
Conductors ≥ 125% of RLA (30 A × 1.25 = 37.5 A; 20 A × 1.25 = 25 A); OCPD not more than 175% of RLA (30 A × 1.75 = 52.5 A; 20 A × 1.75 = 35 A); if that device cannot carry starting current, increase to not more than 225% of RLA (30 A × 2.25 = 67.5 A → 60 A)PV load-side interconnection 120 percent rule (705.12(B)(3)(b))
125% of power source output current + rating of main overcurrent device shall not exceed 120% of busbar ampacity — 200 A busbar × 120% = 240 A; 240 A − 200 A main = 40 A maximum backfed PV breaker