Question 1

What is the maximum distance between supports for 1/2 inch Electrical Metallic Tubing (EMT)?

Accepted Answer

NEC 358.30(A) requires EMT to be securely fastened at least every 10 feet.

Question 2

Type NM cable shall be secured within _____ of every box or cabinet.

Accepted Answer

NEC 334.30 requires Type NM cable to be secured within 12 inches of every outlet box, junction box, cabinet, or fitting.

Question 3

Rigid Metal Conduit (RMC) shall be supported at intervals not exceeding:

Accepted Answer

NEC 344.30(B)(1) requires RMC to be supported at intervals not exceeding 10 feet (unless larger sizes and vertical runs permit greater distance, 10 ft is the standard rule).

Question 4

Liquidtight Flexible Metal Conduit (LFMC) shall be securely fastened within _____ of each box or other conduit termination.

Accepted Answer

NEC 350.30(A) requires LFMC to be secured within 12 inches of the termination.

Question 5

What is the minimum cover requirement for PVC conduit installed under a driveway of a one-family dwelling?

Accepted Answer

Table 300.5 Col 3 (Nonmetallic Raceways) under 'Driveways... One and Two Family Dwellings' requires 18 inches of cover.

Question 6

Nonmetallic-Sheathed Cable (Type NM) is permitted to be used in:

Accepted Answer

NEC 334.10 permits NM cable in one- and two-family dwellings (and multifamily/other structures types III, IV, V). It is prohibited in commercial garages, theaters, etc. by 334.12.

Question 7

Cables installed in shallow grooves in wood studs must be protected by a steel plate if the edge of the hole is less than _____ from the nearest edge of the stud.

Accepted Answer

NEC 300.4(A)(1) requires a 1/16 inch steel plate if the hole/groove is less than 1-1/4 inches from the edge of the wood member.

Question 8

Which wiring method is NOT permitted in a plenum (air-handling) space?

Accepted Answer

NEC 300.22(C) prohibits Type NM cable in spaces used for environmental air (plenums) because it emits toxic fumes when burned. Metal raceways and plenum-rated cables are required.

Question 9

When using Armored Cable (Type AC), an anti-short bushing is:

Accepted Answer

NEC 320.40 requires an insulating bushing (anti-short) at the termination of Type AC cable to protect wires from the sharp metal armor.

Question 10

Surface Metal Raceways (like Wiremold) shall only be installed in:

Accepted Answer

NEC 386.10 states that surface metal raceways shall be permitted in dry locations. 386.12 prohibits them in severe corrosive environments or hoistways (unless listed).

Question 11

Underground service conductors that are not encased in concrete and are buried 18 inches or more below grade shall have their location identified by a warning ribbon placed _____ above the underground installation.

Accepted Answer

NEC 300.5(D)(3) requires a warning ribbon at least 12 inches above the underground installation for service conductors not encased in concrete.

Question 12

When Types NM or AC cable are run through bored holes in framing members, holes shall be bored so that the edge of the hole is not less than _____ from the nearest edge of the wood member.

Accepted Answer

NEC 300.4(A)(1) sets the 1 1/4 inch distance to protect the cable from drywall screws/nails.

Question 13

Flat Cable Assemblies (Type FC) shall be permitted only in:

Accepted Answer

NEC 322.10(1) permits Type FC for exposed locations. It is mounted on a specific channel.

Question 14

Cable trays are considered:

Accepted Answer

NEC 392.2 defines a cable tray system as a unit or assembly of units or sections and associated fittings forming a structural system used to securely fasten or support cables and raceways. It is technically a 'support system' for wiring methods, not a raceway itself (though often treated similarly for fill).

Question 15

According to NEC 2026, Article 722 was expanded to include rules for 'Class 4' systems. Which wiring method is explicitly permitted for Class 4 Fault-Managed Power?

Accepted Answer

Class 4 systems (Fault-Managed Power) require specific cables designated for the safety protocols they use. Type FMP (Fault-Managed Power) is the designation.

Question 16

Expansion fittings for PVC conduit are required where the thermal expansion and contraction is expected to exceed:

Accepted Answer

NEC 352.44 requires expansion fittings where length change is expected to be 1/4 inch (6 mm) or greater in a straight run.

Question 17

The maximum number of 1/4 bends (90 degrees) allowed in a run of conduit between pull points is:

Accepted Answer

NEC 358.26 (and similar for other conduits) limits bends to 360 degrees total (equivalent to four quarter bends).

Question 18

Metal Clad Cable (Type MC) supports are not required when the cable is fished between access points in finished buildings or concealed spaces.

Accepted Answer

NEC 330.30(D)(1) permits MC cable to be unsupported when fished between access points through concealed spaces in finished buildings.

Question 19

In a vertical raceway, 1/0 AWG copper conductors must be supported at intervals not exceeding:

Accepted Answer

NEC Table 300.19(A) requires support for 1/0 AWG copper in vertical raceways at intervals not exceeding 100 feet.

Question 20

What is the minimum depth of working space in front of a 480V panelboard (Condition 2: Exposed Live Parts vs Grounded Wall)?

Accepted Answer

Table 110.26(A)(1). Voltage 151-600V. Condition 2 (Live parts opposite grounded surface/concrete). Distance required is 3 feet 6 inches (3.5 ft). (Condition 1 is 3 ft, Condition 3 is 4 ft).

Question 21

Electrical Nonmetallic Tubing (ENT), also known as 'Smurf Tube', is permitted to be installed:

Accepted Answer

NEC 362.10 allows ENT to be embedded in concrete slabs on grade or above grade. It is generally not permitted in direct sunlight unless marked, nor in theaters (assembly occupancies) unless concealed.

Question 22

When using Service-Entrance Cable (Type SE) for interior branch circuits, the cable must be:

Accepted Answer

NEC 338.10(B)(4) requires Type SE cable used for interior wiring to comply with Part II of Article 334 (NM Cable), excluding 334.80 ampacity limits if insulation is rated higher? Wait. 338.10(B)(4)(a) says interior installations must comply with Part II of Article 334. This invokes the securing/supporting rules of NM (4.5 ft), but the most distinct requirement often tested is that it follows NM rules generally.

Question 23

Splices and taps shall not be made within raceways unless:

Accepted Answer

NEC 376.56 permits splices and taps within metal wireways (which have covers), provided they do not fill more than 75% of the cross-section. Standard conduits (EMT/RMC) cannot contain splices.

Question 24

A box installed in a wet location must be:

Accepted Answer

NEC 314.15 requires boxes in wet locations to be listed for use in wet locations (often marked 'Wet Location' or 'Weatherproof').

Question 25

Insulated bushings are required on raceways containing conductors of _____ or larger.

Accepted Answer

NEC 300.4(G) requires an insulating bushing (or smooth rounded entry) where raceways contain ungrounded conductors 4 AWG or larger entering a cabinet, box, or enclosure.

Question 26

The minimum length of free conductor to be left at each outlet, junction, and switch point for splices is:

Accepted Answer

NEC 300.14 requires at least 6 inches of free conductor, measured from the point in the box where it emerges from its raceway or cable sheath.

Question 27

Horizontal runs of RMC supported by openings through framing members at intervals not exceeding 10 feet and securely fastened within _____ of termination points are permitted.

Accepted Answer

NEC 344.30(B)(4) allows horizontal runs of RMC through framing members to be supported by the members (no extra straps) if fastened within 3 feet of termination.

Question 28

At what distance from a box must the first support be installed for Flexible Metal Conduit (FMC)?

Accepted Answer

NEC 348.30(A) requires FMC to be securely fastened within 12 inches of each box, cabinet, conduit body, or other termination.

Question 29

Underfloor raceways shall not be installed:

Accepted Answer

NEC 390.12(1) prohibits underfloor raceways where subject to corrosive vapors.

Question 30

A fitting is defined as an accessory such as a locknut, bushing, or other part of a wiring system that is intended primarily to perform a ____ function.

Accepted Answer

NEC 100 Definition: A fitting performs a mechanical function rather than an electrical one.

Question 31

Type TC (Tray Cable) cable is permitted to be used:

Accepted Answer

NEC 336.10 permits Type TC cable for power, lighting, control, and signal circuits in cable trays. (Direct burial requires specific listing 'TC-ER' or similar marking).

Question 32

Where conductors 4 AWG and larger enter an enclosure, the insulating bushing is required to protect the conductors. Is a metal bushing with a bakelite throat acceptable?

Accepted Answer

NEC 300.4(G) accepts insulating bushings or 'other identified insulating material'. A metal bushing with an insulating insert (throat) is the standard method of compliance.

Question 33

What is the maximum distance between supports for a vertical run of 500 kcmil copper conductors in a raceway?

Accepted Answer

NEC Table 300.19(A) requires support every 50 feet for conductors 250 kcmil through 500 kcmil copper.

Question 34

When installing PVC conduit, if the temperature change is 40°F, an expansion fitting is required if the run exceeds:

Accepted Answer

NEC 352.44 requires expansion fittings where the length change is 1/4 inch or greater. The specific length of run depends on the calculation (Table 352.44). For a 40°F change, PVC expands approx 1.6 inches per 100 ft. A 1/4 inch change happens in about 15 feet. But the 'code rule' answer is the condition: 'Where the length change is expected to be 1/4 inch or greater'.

Question 35

Busways shall be supported at intervals not exceeding _____ unless otherwise designed and marked.

Accepted Answer

NEC 368.30 requires busways to be supported at intervals not exceeding 5 feet unless otherwise designed and marked.

Question 36

NEC 2026 300.5(D) updates regarding 'Protection from Damage' for underground conductors now emphasizes protecting:

Accepted Answer

The 2026 code reinforces that conductors emerging from grade must be protected by enclosures or raceways (Schedule 80 PVC) to a point 8 feet above grade.

Question 37

Multi-outlet assemblies (like Plugmold) are not permitted:

Accepted Answer

NEC 380.12 prohibits multi-outlet assemblies where concealed.

Question 38

Nonmetallic Extension (surface extensions) shall be run:

Accepted Answer

NEC 382.10 requires Nonmetallic Extensions to be run exposed.

Question 39

The maximum size of Electrical Metallic Tubing (EMT) tubing is:

Accepted Answer

NEC 358.20(B) states the maximum size for EMT is Metric Designator 103 (Trade Size 4).

Question 40

Integrated Gas Spacer Cable (Type IGS) uses which gas for insulation?

Accepted Answer

NEC 326.2 defines Type IGS cable as using Sulfur Hexafluoride (SF6) gas.

Question 41

Strut-type channel raceways shall be supported at intervals not exceeding:

Accepted Answer

NEC 384.30 requires strut-type channel raceways to be supported at intervals not exceeding 10 feet.

Question 42

Auxiliary gutters shall not extend greater than _____ beyond the equipment they supplement.

Accepted Answer

NEC 366.12 states auxiliary gutters shall not extend more than 30 feet beyond the equipment.

Question 43

Cellular Concrete Floor Raceways are limited to conductors not larger than:

Accepted Answer

NEC 372.20 limits conductor size in cellular concrete floor raceways to 1/0 AWG, except by special permission.

Question 44

When raceways are installed in a suspended ceiling used for environmental air (plenum), which type is permitted?

Accepted Answer

NEC 300.22(C) requires metal raceways (like EMT) or plenum-rated cables. Standard PVC and ENT are not permitted due to smoke generation.

Question 45

What is the maximum fill percentage for a conduit over 24 inches long containing more than 2 conductors?

Accepted Answer

Chapter 9 Table 1 limits conduit fill to 40% for over 2 conductors (new or existing).

Question 46