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

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.

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.

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.

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.

Give the multiplier used to calculate the diagonal (travel) length of an offset bend for common angles $22.5^{\circ}$, $30^{\circ}$, and $45^{\circ}$.

Multiplier $= \dfrac{1}{\sin\theta}$: for $22.5^{\circ}\approx 2.6$, for $30^{\circ}=2.0$, for $45^{\circ}\approx 1.4$. Distance between bends $=$ offset depth $\times$ multiplier.

What is the minimum bending radius concern for conductors and what governs it?

Bends must not damage the raceway or reduce its internal diameter; NEC Chapter 9 Table 2 gives minimum bend radii by trade size. For conductors entering boxes/cabinets, 312.6 sets minimum bending space at terminals to prevent conductor damage.

State the free-space volume allowance (in $\text{in}^3$) per conductor for box fill at 14, 12, and 10 AWG (Table 314.16(B)).

14 AWG $= 2.00\,\text{in}^3$, 12 AWG $= 2.25\,\text{in}^3$, 10 AWG $= 2.50\,\text{in}^3$ per conductor.

In box-fill counting, how are equipment grounding conductors and internal cable clamps counted?

All equipment grounding conductors together count as ONE conductor (based on the largest EGC). All internal cable clamps together count as ONE conductor (based on the largest conductor in the box). Each is a single volume allowance.

How is a single yoke/strap (switch or receptacle) counted in box fill?

Each yoke or strap supporting a device counts as TWO conductors, based on the largest conductor connected to that device. (Wide devices spanning multiple gangs count double per the gangs they occupy.)

How are conductors that pass through a box without splice or termination counted in box fill, versus those that originate outside and terminate inside?

A conductor running through the box unbroken counts as ONE. A conductor that enters and terminates (or is spliced) in the box counts as ONE. Conductors that both originate and end within the box (pigtails) are not counted.

Box-fill example: A 4" square box ($21\,\text{in}^3$) contains six 12 AWG conductors, two internal clamps, and one duplex receptacle (12 AWG) plus one 12 AWG EGC. Does it comply?

Count: 6 conductors $+$ 2 for the device yoke $+$ 1 for all clamps $+$ 1 for all grounds $= 10$ units $\times 2.25 = 22.5\,\text{in}^3$. This exceeds $21\,\text{in}^3$, so it does NOT comply; a deeper box is required.

What do the cable abbreviations NM, NMC, AC, MC, and SE designate?

NM = Nonmetallic-sheathed cable (Romex, dry locations, Art. 334); NMC = corrosion-resistant NM; AC = Armored Cable (BX, Art. 320); MC = Metal-Clad cable (Art. 330); SE = Service-Entrance cable (Art. 338).

What is the key grounding difference between AC cable and MC cable?

AC cable's armor (with internal bonding strip) is listed as the equipment grounding path. MC cable's armor is NOT an approved EGC, so MC contains a separate dedicated equipment grounding conductor.

State the support and securing requirements for NM cable per NEC 334.30.

NM cable must be secured within $12"$ of each box/enclosure and supported at least every $4.5\,\text{ft}$ ($54"$) along the run.

When NM cable passes through or is run on framing members, what protection from physical damage is required?

Where run through bored holes, the hole must be $\geq 1\tfrac{1}{4}"$ from the nearest edge; otherwise a $\tfrac{1}{16}"$ steel plate is required. Along the face of studs/rafters it must be protected or kept $\geq 1\tfrac{1}{4}"$ back, per NEC 300.4.

Where is NM cable (Type NM-B) NOT permitted to be used?

NM is prohibited in wet/damp locations, where exposed to corrosive fumes, embedded in concrete/masonry, and (per 334.10/334.12) as service-entrance cable or in certain commercial structures of Types I/II construction.

What is the maximum continuous current rating relationship for a switch (Article 404), and how must general-use snap switches be rated?

Snap switches must be used within their ampere and voltage rating. AC general-use snap switches control AC loads up to their rating and may control inductive loads up to the rated amperes; tungsten (T-rated) switches are required for high-inrush incandescent loads exceeding the AC rating.

Per NEC 404.2(C), what conductor is generally required at switch locations controlling lighting loads?

A grounded (neutral) conductor must be provided at most switch points controlling lighting loads, so electronic/occupancy switches that need standby power can be installed without using the EGC for return current.

How must snap switches be grounded and what is the rule about metal faceplates (404.9)?

Snap switches, including dimmers, must be effectively grounded via the metal yoke connected to an EGC or grounded metal box. Metal faceplates must be grounded; switches in metal faceplate installations require the grounding means to prevent shock.

What is the required mounting position rule for a knife switch and the 'up = on' convention for switches?

For vertically mounted switches/circuit breakers, the up position must be ON (NEC 240.81/404.7). Knife switches must be connected so the blades are de-energized when open.

At what height and condition can a switch serve as the disconnect, and what indicates switch position requirements (404.7)?

General-use switches must clearly indicate ON/OFF. Where used as a disconnecting means and operable from a readily accessible place, the center of the grip must be $\leq 6\,\text{ft }7\,\text{in}$ ($2.0\,\text{m}$) above the floor/working platform.

Per Article 406, when must receptacles be of the tamper-resistant (TR) type?

125 V and 250 V, 15 A and 20 A receptacles in dwelling units (and many other locations like guest rooms, child care, waiting rooms) must be listed tamper-resistant to prevent insertion of foreign objects.

What is the NEC requirement for receptacles installed in wet locations versus damp locations (406.9)?

Damp locations: a weatherproof cover that protects when no plug is inserted (closes when unused). Wet locations: a weatherproof 'in-use' (bubble) cover that protects even with a cord plugged in, for 15/20 A, 125/250 V receptacles.

How must a receptacle be grounded, and what is required when replacing a non-grounding receptacle where no EGC exists (406.4)?

Receptacles must connect to an EGC. Where no EGC exists, replacement options are: a non-grounding type, OR a GFCI-protected receptacle marked 'No Equipment Ground,' OR a grounding type supplied through a GFCI and marked accordingly.

What is the orientation/face-up rule for receptacles installed in countertops or work surfaces (406.5)?

Receptacles must not be installed in a face-up position in countertops or similar work surfaces unless listed for that application, to prevent debris and liquid accumulation in the contacts.

Define a cord connector (cord cap/attachment plug) requirement that the grounding contact must do per Article 406.

Attachment plugs and cord connectors must be made so the grounding pole connection (first to make, last to break) is established before the current-carrying contacts, ensuring grounding continuity precedes energization.

Per Article 410, what clearance must luminaires in clothes closets maintain from the storage space, for surface and recessed fixtures?

Surface-mounted incandescent/LED with completely enclosed light source: $12"$ from storage; surface fluorescent/LED: $6"$; recessed incandescent/LED enclosed: $6"$; recessed fluorescent: $6"$. Open/exposed incandescent lamps are prohibited in closets (410.16).

What is the requirement for luminaires used in wet or damp locations (410.10)?

Luminaires must be listed and marked for the location: 'Suitable for Wet Locations' for wet, 'Suitable for Damp Locations' for damp. Fixtures must be constructed/installed so water cannot accumulate in wiring compartments, lampholders, or other parts.

For recessed luminaires, what distinguishes Type IC from non-IC, and the clearance rule (410.116)?

Type IC luminaires are listed for direct contact with thermal insulation. Non-IC types must have insulation kept $\geq 3"$ away and no combustible material above the fixture except at support points; both limit recessed housing surface temperature for fire safety.

What is the maximum weight a luminaire can be supported by an outlet box alone, and when is independent support required (314.27 / 410.36)?

An outlet box listed for fixture support may support a luminaire up to $50\,\text{lb}$; luminaires heavier than $50\,\text{lb}$ must be supported independently of the outlet box. Boxes supporting ceiling paddle fans must be listed and marked for fan support.

Compare line voltage versus low-voltage lighting per Article 411, and the voltage threshold.

Article 411 covers lighting systems operating at $\leq 30\,\text{V}$ (low-voltage, e.g., $12\,\text{V}$ track/landscape), which must be listed as a complete system or assembled from listed parts. Standard line-voltage luminaires operate at $120/277\,\text{V}$ under Article 410.