ICC R18 Residential Electrician Exam (2023 NEC)

Key Concepts

NEC Purpose, Scope, and Arrangement (Article 90)

• The purpose of the Code is "the practical safeguarding of persons and property from hazards arising from the use of electricity." It "is not intended as a design specification or an instruction manual for untrained persons." (90.2(A))
• Installations not covered include "installations in ships, watercraft other than floating buildings, railway rolling stock, aircraft, or automotive vehicles other than mobile homes and recreational vehicles." (90.2(D)) Mobile homes, recreational vehicles, and floating buildings are covered under 90.2(C).
• Code arrangement: "This Code is divided into the introduction and nine chapters." Chapters 1, 2, 3, and 4 apply generally. Chapters 5, 6, and 7 apply to special occupancies, special equipment, or other special conditions and may supplement or modify the requirements. Chapter 8 covers communications systems and "is not subject to the requirements of Chapters 1 through 7 except where the requirements are specifically referenced in Chapter 8." Chapter 9 consists of tables applicable as referenced. Informative annexes are not part of the requirements. (90.3)
• Enforcement/interpretations: "The authority having jurisdiction for enforcement of the Code has the responsibility for making interpretations of the rules, for deciding on the approval of…

Key Concepts

Number and identification of services. A building or other structure shall be supplied by only one service unless permitted in 230.2(A) through (D) — special conditions (fire pumps, emergency systems, legally required/optional standby, interconnected power production), special occupancies by special permission, capacity requirements (over 2000 amperes at 1000 volts or less), or different characteristics (230.2). Where supplied by more than one service, a permanent plaque or directory is required at each service disconnect location (230.2(E)).

Service ratings. For a one-family dwelling, the service disconnecting means shall have a rating of not less than 100 amperes, 3-wire (230.79(C)). Ground-fault protection of equipment is required for solidly grounded wye services of more than 150 volts to ground but not exceeding 1000 volts phase-to-phase, for each service disconnect rated 1000 amperes or more; maximum GFPE setting 1200 amperes, maximum time delay 1 second for ground-fault currents ≥3000 amperes (230.95, 230.95(A)).

2023 NEC — Feeders (Articles 215, 220, 225)

Key Concepts

• Minimum feeder conductor ampacity. Feeder conductors shall have an ampacity not less than the larger of 215.2(A)(1) or (A)(2). Under 215.2(A)(1), where a feeder supplies continuous loads or any combination of continuous and noncontinuous loads, the minimum size shall have an ampacity not less than the noncontinuous load plus 125 percent of the continuous load. Exception No. 1: if the assembly, including the overcurrent devices, is listed for operation at 100 percent of its rating, ampacity may be the simple sum of continuous plus noncontinuous load.
• 215.2(A)(2) requires ampacity not less than the maximum load after any adjustment or correction factors per 310.14.
• Feeder overcurrent protection — 215.3. The OCPD rating shall not be less than the noncontinuous load plus 125 percent of the continuous load (same exception for 100 percent–rated assemblies).
• Grounded (neutral) conductor — 215.2(B). The feeder grounded conductor shall not be smaller than the equipment grounding conductor size required by 250.122, except that 250.122(F) shall not apply where grounded conductors are run in parallel.
• 215.2(C). Feeder ampacity shall not be less than that of the service conductors where the feeder carries…

Based on the 2023 NEC and Ugly's Electrical References

Key Concepts

Conductor sizing and material - Minimum size for general wiring up to and including 2000 volts: 14 AWG copper or 12 AWG aluminum/copper-clad aluminum (310.3(A)). - Solid aluminum conductors 8, 10, and 12 AWG must be AA-8000 series electrical grade aluminum alloy (310.3(B)). - Where installed in raceways, conductors 8 AWG and larger shall be stranded unless permitted or required to be solid (310.3(C)). - Conductors may be connected in parallel only in sizes 1/0 AWG and larger (310.10(G)(1)). - Insulated conductors in wet locations include Types THWN, THWN-2, XHHW, XHHW-2, RHW, TW, THW, ZW, and others (310.10(C)); THHN is dry and damp only.

Ampacity, temperature and adjustment - Table 310.16 applies to conductors rated 60°C/75°C/90°C, in a 30°C (86°F) ambient, with not more than three current-carrying conductors (310.16). - Bare or covered conductors in free air: 40°C (104°F) ambient, 80°C total conductor temperature, 610 mm/sec (2 ft/sec) wind (310.21). - Type THHN maximum operating temperature: 90°C (194°F), dry and damp (Table 310.4(1)). Type UF: 60°C (140°F), ampacity limited per 340.80. - Rooftop: where the raceway/cable is less than 19 mm (¾ in.) above the roof and exposed…

2023 NEC — Articles 300, 312, 314, 330, 334, 338, 340, 342, 344, 400

Key Concepts

Protection against physical damage (300.4) - Bored holes in wood members: the edge of the hole must be not less than 32 mm (1¼ in.) from the edge of the wood member. Where that distance can't be maintained, the cable or raceway must be protected from screw/nail penetration by a steel plate — 300.4(A)(1). - Cables or raceways laid in notches in wood members must be protected by a steel plate at least 1.6 mm (1/16 in.) thick, of appropriate length and width, covering the area of the wiring — 300.4(A)(2). - Cables/raceways run parallel to framing members where nails or screws are likely to penetrate must keep the nearest outside surface at least 32 mm (1¼ in.) from the edge; otherwise a steel plate or sleeve is required — 300.4(D). - Cables or raceways in shallow grooves to be covered by wallboard, siding, paneling, carpeting or similar finish: protect with 1.6 mm (1/16 in.) steel plate/sleeve or provide not less than 32 mm (1¼ in.) free space for the full length of the groove. RMC, IMC, rigid PVC, RTRC and EMT do…

Key Concepts

Luminaires — heat and combustibles - Luminaires shall be constructed, installed, or equipped with shades or guards so combustible material is not subjected to temperatures above 90°C (194°F) (410.11; also 410.97 for lampholders, 410.115(A) and 410.120 for recessed). - Lampholders over highly combustible material must be unswitched and located at least 2.5 m (8 ft) above the floor, or located/guarded so lamps can't be readily removed or damaged, unless an individual switch is provided for each luminaire (410.12).

Clothes closets (410.16) - Storage space: bounded by side/back walls, from floor up to 1.8 m (6 ft) or the highest rod, 600 mm (24 in.) horizontally from the walls; extends to the ceiling at 300 mm (12 in.) or shelf width, whichever is greater (410.16(A)). - Permitted: surface-mounted or recessed incandescent/LED with completely enclosed light sources, surface or recessed fluorescent, and surface fluorescent/LED identified for use within storage space (410.16(B)). Not permitted: open or partially enclosed lamps, pendant luminaires or lampholders (410.16(C)). - Clearance from storage space: 300 mm (12 in.) for surface-mounted incandescent or LED with completely enclosed source on wall above door or ceiling; 150 mm (6 in.) for surface-mounted fluorescent (410.16(D)).

Key Concepts

Permanently installed pools (Art. 680, Parts I–II) - Permanently wired pool pump motors must be at least 1.5 m (5 ft) from the inside wall of the pool unless listed for a lesser distance or part of a listed assembly — 680.22(B). - The required 125-volt, 15- or 20-ampere receptacle on a general-purpose branch circuit must be not less than 1.83 m (6 ft) and not more than 6.0 m (20 ft) from the inside wall, and not more than 2.0 m (6 ft 6 in.) above the floor/grade — 680.22(A)(1). Other receptacles: not less than 1.83 m (6 ft) — 680.22(A)(3). Circulation/sanitation receptacles: at least 6 ft, GFCI protected, grounding type — 680.22(A)(2). - All receptacles 125–250 volts, 60 amperes or less within 6.0 m (20 ft) of the inside walls require GFCI (680.5(B)) or SPGFCI (680.5(C)) protection — 680.22(A)(4). - Underwater luminaires: no luminaire on supply circuits over 150 volts between conductors — 680.23(A)(4). - Maintenance disconnecting means for utilization equipment other than lighting: readily accessible, within sight, not less than 1.5 m (5 ft) horizontally from inside walls of a pool, spa, fountain, or hot tub unless a barrier provides a 5 ft reach…