Exam Cheat Sheet · Quick Reference
Texas - Master Electrician - NEC Knowledge Portion
Texas · 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
75
Passing score
70%
Exam time
150 min
Administered by
PSI Services Contractor
Format
Reference materials allowed
Texas State Portion 75 questions
Definitions, Theory, and Plans
7 Q · 10%
Purpose and scope of the NEC (practical safeguarding of persons and property)Installations covered vs. not covered by the NECCode arrangement: chapters, their applicability, and hierarchy (Chapters 1–9)Mandatory vs. permissive vs. explanatory rules (shall/shall not vs. shall be permitted)Authority having jurisdiction: enforcement, interpretations, and special permissionExamination and listing of equipment for safetyWiring planning: future expansion, spare raceways, and limiting circuits in enclosuresUnits of measurement: SI vs. inch-pound, hard vs. soft conversion
Electrical Services, Service Equipment, and Separately Derived Systems
11 Q · 16%
Service disconnect requirements: location, rating, number, and grouping (Article 230, Parts VI)Overhead and underground service conductor installation: clearances, wiring methods, minimum sizes, and protection (Article 230, Parts II-IV)Service entrance conductor sizing, ampacity calculations, and continuous load requirements (Article 230, Part IV and Article 220)Grounding and bonding of service-supplied AC systems: main bonding jumper, grounding electrode conductor sizing, and system grounding connections (Article 250, Parts II-III)Separately derived systems: grounding, system bonding jumper, grounding electrode, and bonding requirements (Article 250, Section 250.30)Service equipment overcurrent protection: ground-fault protection of equipment, overload protection, and equipment connected on supply side of service disconnect (Article 230, Part VII)Service equipment marking, listing, surge protection, and emergency disconnect requirements (Article 230, Sections 230.66, 230.67, 230.85)Switchboards, switchgear, and panelboards used as service equipment: bonding, grounding, overcurrent protection, and installation requirements (Article 408)
Electrical Feeders
4 Q · 6%
Minimum feeder conductor ampacity for continuous and noncontinuous loads (125% rule and exceptions)Feeder overcurrent protection requirements and ratingsFeeder and service load calculations using demand factors (dwelling, multifamily, commercial occupancies)Ground-fault protection of equipment for feeder disconnects rated 1000 amperes or moreFeeder conductor identification (grounded, equipment grounding, and ungrounded conductors)Outside feeder requirements including overhead clearances, conductor support, and disconnecting means for separate buildingsSurge-protective device (SPD) requirements for feeders supplying dwelling units and similar occupanciesFeeder tap conductor rules (10-foot, 25-foot, and outside tap provisions)
Branch Circuit Conductors
11 Q · 16%
Minimum ampacity and size requirements for branch-circuit conductors (NEC 210.19)Overcurrent protection ratings for branch circuits including continuous and noncontinuous loads (NEC 210.20)Branch-circuit ratings and permissible loads by circuit size (NEC 210.18, 210.22, 210.23, 210.24)Conductor ampacity tables and adjustment/correction factors for temperature and number of conductors (NEC 310.15, 310.16)Conductor identification for grounded, equipment grounding, and ungrounded conductors (NEC 210.5, 200.6, 310.6)Multiwire branch circuit requirements including disconnecting means and line-to-neutral loads (NEC 210.4)Conductor insulation types, temperature ratings, and permitted uses by location (NEC 310.4, 310.10)Conductors in parallel requirements including minimum size and installation characteristics (NEC 310.10(G))
Electrical Wiring Methods and Electrical Materials
7 Q · 10%
Conductor ampacity tables and temperature ratings (Tables 310.16–310.21)Ampacity correction and adjustment factors for ambient temperature and multiple conductorsProtection of cables and raceways against physical damage (bored holes, notches, framing members)Underground installation requirements including minimum cover depths (Table 300.5(A))Securing and supporting requirements for conduit types (RMC, IMC, PVC, FMC, AC, MC, NM)Uses permitted and not permitted for wiring methods (Type AC, MC, NM/NMC, RMC, IMC, PVC, FMC)Conductor installation rules including same-circuit grouping, parallel conductors, and conductor typesWiring in environmental air spaces, plenums, and protection against fire spread
Electrical Equipment and Devices
8 Q · 11%
Switch types, ratings, and permitted uses (AC/DC snap switches, dimmers, knife switches, circuit breakers as switches)Receptacle ratings, types, installation, and grounding requirementsSwitchboards, switchgear, and panelboard installation, overcurrent protection, and groundingMotor branch-circuit conductors, overload protection, and short-circuit/ground-fault protectionMotor controllers and disconnecting means requirementsLuminaire installation, support, grounding, and location restrictionsTransformer installation, overcurrent protection, and vault requirementsAir-conditioning and refrigerating equipment branch circuits, disconnecting means, and overload protection
Motors and Generators
7 Q · 10%
Motor branch-circuit conductor sizing and ampacity requirements (430.22, 430.24)Motor branch-circuit short-circuit and ground-fault protective device ratings and settings (430.52, Table 430.52(C)(1))Motor overload protection requirements and trip current percentages (430.32)Motor disconnecting means type, location, and rating requirements (430.102, 430.109, 430.110)Motor controller ratings, markings, and design requirements (430.8, 430.83)Motor control circuit overcurrent protection and disconnection (430.72, 430.75)Generator installation requirements including overcurrent protection, conductor ampacity, and disconnecting means (445.12, 445.13, 445.18, 445.19)Motor and controller grounding and bonding requirements (430.242, 430.244, 430.245)
Electrical Control Devices and Disconnecting Means
3 Q · 4%
Motor disconnecting means requirements: location, type, and rating (Article 430, Part IX)Switch ratings and load types for general-use snap switches, dimmers, and control switches (Article 404)Motor controller ratings, types, and disconnecting means (Article 430, Parts VII and IX)Overcurrent protection for motor branch circuits: rating and setting per Table 430.52(C)(1)Panelboard, switchboard, and switchgear overcurrent protection and disconnecting means (Articles 408 and 240)Industrial control panel disconnecting means, overcurrent protection, and short-circuit current rating (Article 409)Switch enclosure requirements: accessibility, grounding, and installation in damp/wet locations (Article 404)Circuit breaker use as switch or motor controller: marking, indicating, and application requirements (Articles 240 and 404)
Special Occupancies, Equipment, and Conditions
8 Q · 11%
Classification of hazardous locations by Class (I, II, III) and Division (1 and 2)Material group classifications for Class I (Groups A, B, C, D) and Class II (Groups E, F, G) locationsProtection techniques for hazardous locations (explosionproof, dust-ignitionproof, intrinsic safety, purged/pressurized, nonincendive, etc.)Wiring methods and sealing requirements for Class I, II, and III Division 1 and 2 locationsEquipment requirements and markings for hazardous classified locations (temperature codes, class, division, group)Grounding and bonding requirements specific to hazardous classified locationsSpecial occupancy area classification and wiring requirements for commercial garages, aircraft hangars, motor fuel dispensing facilities, and cannabis oil equipmentZone classification system (Zones 0, 1, 2 and Zones 20, 21, 22) as an alternative to the Division system
Renewable Energy Technologies
4 Q · 6%
PV system maximum voltage calculations and temperature correction factorsRapid shutdown requirements for PV systems on buildingsPV system disconnecting means requirements and markingsOvercurrent protection for PV system DC circuitsArc-fault circuit protection for PV DC circuitsGrounding and bonding of PV system equipment and arraysEnergy storage system (ESS) disconnecting means and circuit sizingInterconnected power source connections to load-side distribution equipment
Key Distinctions
Mandatory Rules ('shall'/'shall not')vsInformational Notes
Mandatory rules use 'shall' or 'shall not' and are enforceable requirements, while informational notes are explanatory only and not enforceable as Code requirements.
NEC 90.5(A)Chapters 1–4 (General)vsChapter 8 (Communications)
Chapters 1–4 apply generally to all electrical installations, whereas Chapter 8 covers communications systems and is NOT subject to Chapters 1–7 except where specifically referenced in Chapter 8.
NEC 90.3Chapters 1–4 (General)vsChapters 5, 6, and 7 (Special)
Chapters 1–4 apply to all installations, while Chapters 5, 6, and 7 apply to special occupancies, equipment, or conditions and may supplement or modify the general requirements.
NEC 90.3Continuous Load (125% rule)vsNoncontinuous Load (100% rule)
Branch-circuit and feeder conductors must be sized at 125% of continuous loads but only 100% of noncontinuous loads, unless separately installed pressure connections are used at both ends (then 100% of each is permitted).
NEC 210.19(A)(1)Separately Installed Pressure Connections ExceptionvsStandard 125% Continuous Load Rule
When separately installed pressure connections per 110.14(C)(2) are used at both supply and load ends, conductors may be sized at 100% of continuous plus noncontinuous load rather than the standard 125% multiplier for continuous loads.
NEC 210.19(A), Exception to (1) and (2)Wet Location (Underground Interior)vsGeneral Underground Burial
The interior of enclosures or raceways installed underground is specifically classified as a wet location requiring wet-rated conductors, while general underground burial has minimum cover requirements (e.g., 600 mm / 24 in.).
NEC 300.5(B)SI (Metric) UnitsvsInch-Pound Units
The NEC gives preference to SI (metric) units, which appear first; inch-pound units immediately follow in parentheses.
NEC 90.9(A) and 90.9(B)Authority Having Jurisdiction (AHJ)vsNEC Code Text
The AHJ is responsible for interpreting NEC rules, approving equipment and materials, and granting special permissions, while the Code text itself establishes the mandatory and permissive requirements.
Article 90.4(B)NEC Purpose (Safety)vsNEC as 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.
NEC 90.2(A)Vertical Raceway Support — 18 AWG–8 AWG CoppervsVertical Raceway Support — 2/0–4/0 AWG Copper
Copper conductors 18 AWG through 8 AWG in vertical raceways must be supported at maximum 30 m (100 ft) intervals, while 2/0 AWG through 4/0 AWG conductors require support at maximum 25 m (80 ft) intervals.
Table 300.19(A)Ferrous Metal Raceway — Conductor Grouping RequiredvsNon-Ferrous Raceway
When AC conductors are in ferrous metal raceways, all phase, grounded, and equipment grounding conductors must be grouped together to prevent inductive heating; this is specific to ferrous (magnetic) materials.
NEC 300.20(A)Multiwire Branch Circuit Grounded Conductor ContinuityvsStandard Single-Circuit Grounded Conductor
In a multiwire branch circuit, grounded conductor continuity must NOT depend on device connections (e.g., receptacles) so that removing a device cannot interrupt the neutral to other circuits sharing it.
NEC 300.13(B)Key Terms
Purpose of the NEC (NEC 90.1/90.2(A)) NEC 90.2(A)
The practical safeguarding of persons and property from hazards arising from the use of electricity; the Code is not a design specification or instruction manual for untrained persons.
Mandatory Rule (NEC 90.5(A)) NEC 90.5(A)
A Code rule that specifically requires or prohibits an action, characterized by the use of the terms 'shall' or 'shall not.'
Informational Note (NEC 90.5(C)) Article 90.5(C)
Explanatory material included in the NEC that is informational only and not enforceable as a requirement of the Code.
Authority Having Jurisdiction — AHJ (NEC 90.4) Article 90.4(B)
The entity responsible for enforcing the NEC, making interpretations of its rules, approving equipment and materials, and granting special permissions.
NEC Code Arrangement — Chapter 8 Exception (NEC 90.3) NEC 90.3
Chapter 8 (Communications Systems) is not subject to the requirements of Chapters 1 through 7 unless those requirements are specifically referenced within Chapter 8.
NEC Scope Exclusions (NEC 90.2(D)) NEC 90.2(D)
The NEC 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.
SI Units Preference (NEC 90.9(A)/(B)) NEC 90.9(A) and 90.9(B)
The NEC uses metric (SI) units as the system of preference, with SI values appearing first and inch-pound values immediately following in parentheses.
Equipment/Material Approval Basis (NEC 90.7) NEC 90.7
Approval of equipment and materials is based on examinations for safety made under standard conditions by qualified testing organizations that conduct factory inspections and field service-value determinations.
Continuous Load NEC 210.19(A)(1)
A load where the maximum current is expected to continue for 3 hours or more; branch-circuit and feeder conductors must be sized at a minimum of 125% of this load.
Minimum Free Conductor Length (NEC 300.14) NEC 300.14
At least 150 mm (6 in.) of free conductor, measured from where it emerges from its raceway or cable sheath, must be left at each outlet, junction, and switch point.
Underground Interior as Wet Location (NEC 300.5(B)) NEC 300.5(B)
The interior of enclosures or raceways installed underground is classified as a wet location, requiring conductors and cables to comply with wet location installation requirements.
Minimum Burial Depth — Direct Burial Cable (NEC Table 300.5(A)) Table 300.5(A)
Direct burial cables rated 1000 V or less in general locations require a minimum cover of 600 mm (24 in.).
Raceway Sealing for Condensation (NEC 300.7(A)) NEC 300.7(A)
Where a raceway passes between areas of different temperatures and condensation is a problem, the raceway must be sealed to prevent warm air from circulating to the colder section.
Inductive Heating Prevention — Ferrous Raceways (NEC 300.20(A)) NEC 300.20(A)
To prevent inductive heating of ferrous metal enclosures or raceways carrying AC, all phase conductors, grounded conductors, and equipment grounding conductors of the same circuit must be grouped together.
Backfill Restrictions for Underground Cables (NEC 300.5(F)) NEC 300.5(F)
Backfill containing large rocks, paving materials, cinders, sharply angular substances, or corrosive material must not be placed in excavations where it could damage cables, raceways, or conductors.
Temperature Correction Factors for Flexible Cords (NEC 400.5(A)) NEC 400.5(A)
When flexible cords or cables are used in ambient temperatures other than 30°C (86°F), the temperature correction factors from NEC 310.15(B) corresponding to the cord's temperature rating must be applied to its ampacity.
Formulas to Know
Branch-Circuit Conductor Minimum Ampacity (Standard Rule)
Ampacity ≥ (Noncontinuous Load × 1.00) + (Continuous Load × 1.25)Branch-Circuit Conductor Minimum Ampacity (Pressure Connection Exception)
Ampacity ≥ Noncontinuous Load + Continuous Load [100% each, when separately installed pressure connections per 110.14(C)(2) used at both ends]Feeder Conductor Minimum Ampacity
Ampacity ≥ (Noncontinuous Load × 1.00) + (Continuous Load × 1.25)Ampacity Correction for Ambient Temperature (Flexible Cords/Cables)
Corrected Ampacity = Tabulated Ampacity × Temperature Correction Factor [from NEC 310.15(B) for cord/cable temperature rating]Minimum Free Conductor at Box
Free conductor length ≥ 150 mm (6 in.) measured from point of emergence from raceway or cable sheathMinimum Burial Depth — Direct Burial Cable (General Location)
Minimum cover = 600 mm (24 in.)Vertical Raceway Support Interval — Copper 18 AWG–8 AWG
Maximum support spacing = 30 m (100 ft)Vertical Raceway Support Interval — Copper 2/0 AWG–4/0 AWG
Maximum support spacing = 25 m (80 ft)Cable-Through-Wood Framing Edge Distance
Minimum distance from edge of bored hole to edge of wood member = 32 mm (1-1/4 in.)