Journeyman/Master Electrician License Exam Wiring Methods, Materials, and Equipment Syllabus

Wiring Methods, Materials, and Equipment syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Wiring Methods, Materials, and Equipment in Journeyman/Master Electrician License Exam, not a summary of it.

1. 1

   Conductors and Insulation

   3 topics

   • Conductor Types and Temperature Ratings
     • THHN, THWN-2, XHHW-2 and 60/75/90 C columns
     • Termination temperature limitations (110.14(C))
   • Ampacity and Adjustment Factors (Article 310)
     • Table 310.16 ampacities
     • Ambient temperature correction factors
     • Conductor bundling/fill adjustment for 4 or more current-carrying conductors
   • Conductor Identification and Color Coding
     • Grounded conductor (white/gray) requirements
     • High-leg (delta) identification
2. 2

   Raceways, Boxes, and Fittings

   4 topics

   • Conduit and Tubing Types
     • RMC, IMC, EMT, PVC, FMC, and LFMC applications
     • Support spacing and securing requirements
   • Conduit Fill and Bending
     • Chapter 9 Tables 1, 4, and 5 fill calculations
     • Maximum 360 degrees of bend between pull points
     • Minimum bending radius
   • Outlet, Device, and Junction Box Fill
     • Box fill calculation (314.16)
     • Conductor, device, clamp, and equipment grounding allowances
     • Pull and junction box sizing (314.28)
   • Cable Wiring Methods
     • NM, AC, MC, and UF cable applications and limitations
     • Securing and support intervals
3. 3

   Switches, Receptacles, and Luminaires

   3 topics

   • Switches (Article 404)
     • Three-way and four-way switching
     • Grounding of snap switches
   • Receptacles and Cord Connectors (Article 406)
     • Tamper-resistant and weather-resistant requirements
     • Receptacle mounting and faceplate rules
   • Luminaires and Lighting (Article 410)
     • Clearances in clothes closets
     • Luminaires in wet and damp locations

Wiring Methods, Materials, and Equipment flashcards for Journeyman/Master Electrician License Exam

24 of 51 cards from the Wiring Methods, Materials, and Equipment deck — real questions with worked answers.

1. In NEC conductor insulation type letters, what do the letters T, H, HH, W, and N each indicate?

   T = thermoplastic insulation; H = heat-resistant ($75^{\circ}\text{C}$); HH = high heat-resistant ($90^{\circ}\text{C}$); W = moisture-resistant (suitable for wet locations); N = nylon outer jacket.

2. What are the temperature ratings of THHN and THWN-2 conductor insulation, and where may each be used?

   THHN is rated $90^{\circ}\text{C}$ in dry/damp locations only. THWN-2 is rated $90^{\circ}\text{C}$ in dry, damp, and wet locations. Most building wire is dual-rated THHN/THWN-2.

3. For most general building wiring, what is the highest conductor temperature rating that may actually be used for ampacity, and why?

   Even with $90^{\circ}\text{C}$ insulation, terminations on equipment limit ampacity to the $60^{\circ}\text{C}$ column for circuits $\leq 100\,\text{A}$ (or #14-#1 AWG) and the $75^{\circ}\text{C}$ column above that, per NEC 110.14(C). The $90^{\circ}\text{C}$ column is generally used only for derating calculations.

4. Which conductor types are listed for direct burial, and which common insulation is rated for use in wet locations?

   USE and UF cable are listed for direct burial. For wet locations, conductors marked W (such as THWN-2, XHHW-2) are required; THHN alone is not permitted in wet locations.

5. What is the difference between an aluminum conductor terminal marked CO/ALR versus one marked AL-CU?

   CO/ALR identifies switches and receptacles ($15$ and $20\,\text{A}$) listed for direct connection to aluminum wire. AL-CU marks lugs/connectors rated for both aluminum and copper conductors. Devices marked only CU are copper-only.

6. Define ampacity as used in NEC Article 100/310.

   Ampacity is the maximum current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating.

7. What is the ampacity of a single THWN-2 copper conductor at the $75^{\circ}\text{C}$ column for sizes 12, 10, and 8 AWG (Table 310.16)?

   12 AWG $= 25\,\text{A}$, 10 AWG $= 35\,\text{A}$, 8 AWG $= 50\,\text{A}$. (Note the small-conductor overcurrent limits of 310.16 still cap 14/12/10 AWG at 15/20/30 A.)

8. State the conductor ampacity adjustment factors of NEC Table 310.15(C)(1) for 4-6, 7-9, and 10-20 current-carrying conductors in a raceway.

   4-6 conductors: $80\%$; 7-9 conductors: $70\%$; 10-20 conductors: $50\%$ of the base ampacity.

9. Write the formula for the temperature-corrected, derated ampacity of a conductor.

   $$I_{\text{allowed}} = I_{\text{table}} \times F_{\text{temp}} \times F_{\text{adj}}$$ where $F_{\text{temp}}$ is the ambient temperature correction factor (Table 310.15(B)) and $F_{\text{adj}}$ is the conductor count adjustment factor (Table 310.15(C)(1)).

10. Worked example: Eight 8 AWG THHN copper conductors ($90^{\circ}\text{C}$ base $= 55\,\text{A}$) share a raceway in a $40^{\circ}\text{C}$ ambient. What is the adjusted ampacity?

    Temp correction at $40^{\circ}\text{C}$ for $90^{\circ}\text{C}$ wire $= 0.91$; adjustment for 7-9 conductors $= 0.70$. $$55 \times 0.91 \times 0.70 \approx 35\,\text{A}$$

11. Which conductors count as 'current-carrying' for adjustment factors, specifically regarding neutrals and grounds?

    The equipment grounding conductor is never counted. A neutral carrying only the unbalanced current of a balanced system is not counted, but a neutral on a 3-wire circuit from a 4-wire wye (carrying harmonic/major load) IS counted as current-carrying.

12. What is the standard color coding for grounded (neutral) conductors and equipment grounding conductors per NEC 200.6 and 250.119?

    Grounded/neutral conductors: white or gray, or three continuous white stripes. Equipment grounding conductors: green, green with yellow stripe, or bare.

13. In a 208Y/120 V three-phase system, what is the common phase color code for A, B, and C?

    Phase A = black, Phase B = red, Phase C = blue. (The neutral is white/gray.) Colors above 50 V are not mandated by NEC for ungrounded conductors but this is the widely used convention.

14. What color identification is conventionally used for a 480Y/277 V three-phase system's phases?

    Phase A = brown, Phase B = orange (or purple), Phase C = yellow, with gray neutral. This distinguishes 480 V from 208 V (black/red/blue) systems.

15. On a 4-wire delta high-leg system, how must the high-leg (stinger) conductor be identified per NEC 110.15?

    The phase conductor with the higher voltage to ground (the high leg, $\approx 208\,\text{V}$ to neutral) must be marked orange or by other effective means at any point where the neutral is also present.

16. What does NEC permit for re-identifying a white conductor used as an ungrounded conductor in a cable assembly?

    In cables (e.g., for switch loops), a white conductor may be reidentified as ungrounded by permanently marking it with a color other than white, gray, or green (such as black tape or paint) at each visible/accessible termination.

17. Compare RMC, IMC, and EMT: which is threaded heavy-wall, which is thinner threaded, and which is thin-wall threadless?

    RMC (Rigid Metal Conduit) = thickest, threaded; IMC (Intermediate Metal Conduit) = lighter wall than RMC but still threaded, same outside diameter; EMT (Electrical Metallic Tubing) = thin-wall, not threaded, uses set-screw or compression fittings.

18. What do the abbreviations PVC, ENT, LFNC, and LFMC stand for in conduit/tubing wiring methods?

    PVC = Rigid Polyvinyl Chloride Conduit (Article 352); ENT = Electrical Nonmetallic Tubing (flexible corrugated, Article 362); LFNC = Liquidtight Flexible Nonmetallic Conduit (356); LFMC = Liquidtight Flexible Metal Conduit (350).

19. Which two PVC conduit wall thicknesses are most common, and how do they differ?

    Schedule 40 (thinner wall, normal duty) and Schedule 80 (thicker wall, reduced interior area, used where subject to physical damage). Schedule 80 has lower fill capacity for the same trade size.

20. Why must EMT and other metal raceways not be used as the sole equipment ground in some cases, and what governs raceway-as-EGC?

    NEC 250.118 lists which raceways qualify as equipment grounding conductors. EMT, RMC, and IMC qualify when properly installed with listed fittings; flexible types (FMC/LFMC) qualify only within length and ampere limits, otherwise a separate EGC is required.

21. State the NEC conduit fill limits for 1 conductor, 2 conductors, and 3 or more conductors (Chapter 9, Table 1).

    1 conductor $= 53\%$ of conduit area; 2 conductors $= 31\%$; 3 or more conductors $= 40\%$ of the conduit cross-sectional area.

22. Why is the 2-conductor fill limit ($31\%$) lower than both the 1-conductor ($53\%$) and 3-or-more ($40\%$) limits?

    With exactly two conductors, the geometry leaves a narrow elliptical clearance that increases jamming risk during a pull, so the code uses a more conservative $31\%$ to ease pulling.

23. What is the maximum total bend allowed between pull points in a conduit run, and why?

    A maximum of $360^{\circ}$ total bends (e.g., four $90^{\circ}$ bends) between pull boxes/outlets is permitted, to limit pulling tension and conductor damage.

24. For EMT, what is the typical take-up (deduction) used when bending a $90^{\circ}$ stub for 1/2", 3/4", and 1" conduit?

    $\tfrac{1}{2}" = 5"$ take-up, $\tfrac{3}{4}" = 6"$, $1" = 8"$. The bender is placed at (desired stub height $-$ take-up) measured from the conduit end.

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