North Carolina Electrical Contractor - Single-Family Detached Residential Dwelling (SP-SFD)

NC Electrical Contractor, SP-SFD

Key Concepts

Fundamental principle - The effective ground-fault current path must be a low-impedance circuit capable of safely carrying the maximum ground-fault current likely to be imposed on it from any point on the wiring system to the electrical supply source. The earth shall not be considered as an effective ground-fault current path — NEC 2020, 250.4(A)(5).

Systems required to be grounded - AC systems of less than 50 volts shall be grounded where supplied by transformers if the transformer supply system exceeds 150 volts to ground; where the transformer supply system is ungrounded; or where installed outside as overhead conductors — 250.20(A). - Conductor to be grounded on a single-phase, 3-wire system: the neutral conductor — 250.26(2).

NC Electrical Contractor, SP-SFD · 4 questions (10% of exam)

Key Concepts

Location in circuit - Overcurrent protection shall be provided in each ungrounded circuit conductor at the point where the conductors receive their supply, except as specified in 240.21(A) through (H); conductors supplied under those exceptions shall not supply another conductor except through an OCPD meeting 240.4 (NEC 2020, 240.21). - Feeder taps may be made without overcurrent protection at the tap per 240.21(B)(1) through (B)(5), at any point on the load side of the feeder OCPD. 240.4(B) shall not be permitted for tap conductors (NEC 2020, 240.21(B)). - 25-ft tap rule: tap ampacity not less than one-third the rating of the OCPD protecting the feeder; taps terminate in a single circuit breaker or single…

North Carolina Electrical Contractor — Single-Family Detached Residential Dwelling (SP‑SFD) · 3 questions (8% of exam)

Key Concepts

Conductors for general wiring (Article 310) - Minimum conductor size for voltage ratings up to and including 2000 volts: 14 AWG copper or 12 AWG aluminum or copper-clad aluminum, except as permitted elsewhere in the Code — 310.3(A). - Where installed in raceways, conductors 8 AWG and larger shall be stranded, unless specifically permitted or required elsewhere to be solid — 310.3(C). - Conductors shall be aluminum, copper-clad aluminum, or copper unless otherwise specified; solid aluminum 8, 10, and 12 AWG shall be AA‑8000 series alloy — 310.3(B). - Parallel conductors are permitted only in sizes 1/0 AWG and larger — 310.10(G)(1). Paralleled conductors must be the same…

NC Electrical Contractor (SP-SFD) · 4 questions, 10% of exam Subtopics: General information · Sizing requirements

Key Concepts

Round boxes (314.2). Round boxes shall not be used where conduits or connectors requiring the use of locknuts or bushings are to be connected to the side of the box. (The curved surface will not seat the locknut or bushing properly.)

Nonmetallic boxes (314.3). Nonmetallic boxes are permitted only with open wiring on insulators, concealed knob-and-tube wiring, cabled wiring methods with entirely nonmetallic sheaths, flexible cords, and nonmetallic raceways. Exception No. 1: where internal bonding means are provided between all entries, nonmetallic boxes shall be permitted to be used with metal raceways or metal-armored cables.

NC Electrical Contractor (SP-SFD) · 4 questions · 10% of exam

Key Concepts

Overhead clearances (230.24) - Above roofs: vertical clearance not less than 2.5 m (8 ft) above the roof surface, maintained not less than 900 mm (3 ft) in all directions from the roof edge — 230.24(A). - Exception No. 2: where voltage between conductors does not exceed 300 and the roof slope is 100 mm in 300 mm (4 in. in 12 in.) or greater, reduction to 900 mm (3 ft) is permitted. (A 120/240-volt service on a 5-in-12 roof meets both conditions.) - Exception No. 3: reduction above only the overhanging portion to not less than 450 mm (18 in.) where voltage does not exceed 300, not more than 1.8 m (6…

NEC Article 430 — Motors, Motor Circuits, and Controllers

Key Concepts

Branch-circuit conductor ampacity — single motor - Conductors supplying a single motor used in a continuous duty application shall have an ampacity of not less than 125 percent of the motor full-load current rating, as determined by 430.6(A)(1), or not less than specified in 430.22(A) through (G). (NEC 2020, 430.22) - DC motor, rectifier supplied: where a rectifier bridge of the single-phase, half-wave type is used, the conductors between the field wiring output terminals of the rectifier and the motor shall have an ampacity of not less than 190 percent of the motor full-load current rating. (NEC 2020, 430.22(A)) - Wye-start, delta-run motor: conductors between the controller and the motor shall be **not less than…

NEC 2020 (NFPA 70), Article 680 and Article 550

Key Concepts

Storable pools (680.31 through 680.35) - Receptacles shall not be located less than 1.83 m (6 ft) from the inside walls of a storable pool, storable spa, or storable hot tub — 680.34. The distance measured is the shortest path the supply cord of a connected appliance would follow without piercing a floor, wall, ceiling, hinged/sliding doorway, window opening, or other effective permanent barrier. - A storable-pool lighting assembly over the low-voltage contact limit but not over 150 volts must be listed as an assembly, have no exposed metal parts, an impact-resistant polymeric lens and body, and an integral GFCI with open-neutral protection — 680.33(B). - Within the low-voltage contact limit, the cord-and-plug assembly must…

Key Concepts

Required dwelling-unit branch circuits (Article 210). - Two or more 20-ampere small-appliance branch circuits shall be provided for all receptacle outlets specified by 210.52(B) — NEC 2020, 210.11(C)(1). Kitchen countertop receptacles fall under 210.52(B), so they must be on those 20-ampere circuits, not a 15-ampere general-purpose circuit. - At least one additional 20-ampere laundry branch circuit, with no other outlets — 210.11(C)(2). One or more 120-volt, 20-ampere bathroom branch circuits, with no other outlets — 210.11(C)(3). - At least one 120-volt, 20-ampere garage branch circuit with no other outlets; its Exception permits that circuit to supply readily accessible outdoor receptacle outlets — NEC 2020, 210.11(C)(4). No such allowance exists for the small-appliance, laundry, or bathroom circuits. - Each multiwire branch circuit shall have a…

Key Concepts

Luminaire locations (Art. 410, Part II) - Bathtub/shower zone: no parts of cord-connected luminaires, chain-, cable-, or cord-suspended luminaires, lighting track, pendants, or ceiling-suspended (paddle) fans within a zone measured 900 mm (3 ft) horizontally and 2.5 m (8 ft) vertically from the top of the bathtub rim or shower stall threshold; the zone is all-encompassing and includes the space directly over the tub or shower — 410.10(D)(1). - Luminaires within the actual outside dimension of the tub or shower up to 2.5 m (8 ft) vertically must be marked suitable for damp locations or wet locations; those subject to shower spray must be marked suitable for wet locations — 410.10(D)(2). - Luminaires under metal-corrugated sheet roof decking: not less than **38 mm (1½…

NC Electrical Contractor – Single-Family Detached Residential Dwelling (SP-SFD)

Key Concepts

Definitions (Article 100) - Continuous load — a load where the maximum current is expected to continue for 3 hours or more. (NEC 2020, Article 100) - In Sight From (Within Sight From, Within Sight) — equipment that is visible and not more than 15 m (50 ft) distant from the other equipment. Both conditions must be met; visibility alone or distance alone is not sufficient. (NEC 2020, Article 100) - Ampacity — the maximum current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating. (Article 100) - Accessible, Readily (Readily Accessible) — capable of being reached quickly for operation, renewal, or inspection without requiring the…

Key Concepts

Licensing law (G.S. Ch. 87, Art. 4) - Electrical contracting = "engaging or offering to engage in the business of installing, maintaining, altering or repairing any electric work, wiring, devices, appliances or equipment" (G.S. 87-43). A license in the applicable classification is required. - "In each separate place of business operated by an electrical contractor at least one listed qualified individual shall be regularly on active duty" and available to supervise and direct all electrical wiring or installation work (G.S. 87-43; Ch. 3). - Board: seven members, staggered seven-year terms — one from the Dept. of Insurance (designated by the Commissioner), one representing the NC Association of Electrical Contractors, and five appointed by the Governor (G.S. 87-39(a),(b); Ch. 3). - **G.S. 87-43.3 classification limits…