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

Passing score

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%

Electrical Services, Service Equipment, and Separately Derived Systems 11 Q · 16%

Electrical Feeders 4 Q · 6%

Branch Circuit Conductors 11 Q · 16%

Electrical Wiring Methods and Electrical Materials 7 Q · 10%

Electrical Equipment and Devices 8 Q · 11%

Motors and Generators 7 Q · 10%

Electrical Control Devices and Disconnecting Means 3 Q · 4%

Special Occupancies, Equipment, and Conditions 8 Q · 11%

Renewable Energy Technologies 4 Q · 6%

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 90.3

Chapters 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 90.3

Continuous 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 AmpacityAmpacity ≥ (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 BoxFree conductor length ≥ 150 mm (6 in.) measured from point of emergence from raceway or cable sheath

Minimum Burial Depth — Direct Burial Cable (General Location)Minimum cover = 600 mm (24 in.)

Vertical Raceway Support Interval — Copper 18 AWG–8 AWGMaximum support spacing = 30 m (100 ft)

Vertical Raceway Support Interval — Copper 2/0 AWG–4/0 AWGMaximum support spacing = 25 m (80 ft)

Cable-Through-Wood Framing Edge DistanceMinimum distance from edge of bored hole to edge of wood member = 32 mm (1-1/4 in.)

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