ICC F49 Electrical Contractor Exam (2014 NEC)

Key Concepts

Article 90 — Purpose, Scope, Arrangement - The NEC covers premises wiring, yards, lots, parking lots, carnivals, industrial substations, floating buildings, and utility office buildings, warehouses, garages, machine shops and recreational buildings that are not an integral part of a generating plant, substation, or control center [90.2(A)]. - The Code does not cover installations underground in mines or self-propelled mobile surface mining machinery and its attendant electrical trailing cable [90.2(B)(2)]. - Chapter 8 covers communications systems and is not subject to Chapters 1 through 7 except where specifically referenced in Chapter 8 [90.3]. Chapters 1–4 apply generally; 5, 6, 7 supplement or modify; Chapter 9 is tables applicable as referenced. - Mandatory rules use shall/shall not; permissive rules use shall be permitted / shall not be required; informational notes are not enforceable [90.5].

Key Concepts

Number of services (230.2). A building is supplied by only one service unless 230.2(A) through (D) permits more. 230.2(A) special conditions (no special permission needed): fire pumps, emergency systems, legally required standby, optional standby, parallel power production systems, and systems designed for connection to multiple sources of supply for the purpose of enhanced reliability. 230.2(B) multiple-occupancy buildings with no accessible space, or a single building large enough to make two or more services necessary — by special permission only. 230.2(C): capacity requirements in excess of 2000 amperes at 1000 volts or less; single-phase load greater than the serving agency normally supplies through one service; or by special permission. 230.2(D): different voltages, frequencies, or phases, or different uses such as different rate schedules. 230.2(E): a permanent plaque or directory at each service disconnect location denoting all other services, feeders, and branch circuits and the area served by each. For 230.40 Ex. No. 2 only, underground sets 1/0 AWG and larger to the same location, connected at the supply end but not the load…

Key Concepts

• Branch-circuit ratings. For other than individual branch circuits, ratings shall be 15, 20, 30, 40, and 50 amperes (210.3). Exception: multioutlet branch circuits greater than 50 A are permitted to supply nonlighting outlet loads on industrial premises under qualified supervision; where a circuit is rated higher than 50 A, receptacle rating shall not be less than the branch-circuit rating (210.21(B)(3)).
• Continuous loads — branch circuits. Conductor ampacity and OCPD rating shall not be less than the noncontinuous load plus 125 percent of the continuous load (210.19(A)(1)(a), 210.20(A)). The 100-percent-rated assembly exception permits the simple sum.
• Continuous loads — feeders. Same rule for feeder conductors (215.2(A)(1)(a)) and feeder overcurrent devices (215.3).
• Feeder vs. service conductors. Feeder conductor ampacity shall not be less than that of the service conductors where the feeder carries the total load supplied by service conductors with an ampacity of 55 amperes or less (215.2(A)(3)).
• Feeder grounded conductor shall not be smaller than required by 250.122 (215.2(A)(2)); 250.122(F) does not apply where grounded conductors run…

Key Concepts

Ampacity rules (Art. 310) - Where more than one ampacity applies to adjacent portions of a circuit, the lowest value must be used; the Exception permits the higher ampacity beyond the transition point for 10 ft or 10 percent of the circuit length figured at the higher ampacity, whichever is less — 310.15(A)(2) Exception. - Rooftop temperature adders of Table 310.15(B)(3)(c) must be added to the outdoor ambient temperature, but Type XHHW-2 is exempt from that ampacity adjustment — 310.15(B)(3)(c) Exception. - Adjustment factors for more than three current-carrying conductors do not apply to conductors entering/leaving an outdoor trench protected in RMC, IMC, PVC, or RTRC where the raceway length does not exceed 10 ft and the conductors do not exceed four — 310.15(B)(3)(a). - On a 4-wire, 3-phase wye circuit where the major portion of the load is nonlinear, the neutral is counted as current-carrying [310.15(B)(5)]; the equipment grounding conductor is not counted [310.15(B)(6)]. - Burial deeper than the applicable underground table permits a derating of **6 percent per 1 ft…

Key Concepts

Motor conductors (Article 430, Part II) - Single continuous-duty motor branch-circuit conductors: not less than 125% of motor full-load current — 430.22(A). - Wye-start, delta-run motor: conductors between controller and motor not less than 72 percent of FLC per 430.22(C); informational note explains the individual conductors carry 58 percent, and 58% × 1.25 = 72%. Part-winding motors use 62.5% under 430.22(D). - Several motors (feeder): 125% of the largest motor FLC plus the sum of the other FLCs — 430.24. Exception No. 2: conductors supplying motor-operated fixed electric space-heating equipment comply with 424.3(B) instead. Exception No. 3 permits sizing on interlocked loads. 430.26 lets the AHJ grant a feeder demand factor. - Feeder taps over 7.5 m (25 ft): 430.28 Exception applies only in high-bay manufacturing buildings over 11 m (35 ft) high at walls with qualified-person maintenance; conditions include one-third feeder ampacity, no splices, raceway, not over 7.5 m (25 ft) horizontal and 30.0 m (100 ft) total, tap not made less than 9.0 m (30 ft) from the floor, and…

Key Concepts

Classification (Articles 500/505) - Class I, Division 1 = ignitable gas/vapor normally present under normal conditions (NEC 500.5(B)(1)). - Zone-marked equipment listed and marked per 505.9(C)(2) for Zone 0, 1, or 2 is permitted in Class I, Division 2 for the same gas with a suitable temperature class; only Zone 0–marked equipment is additionally permitted in Class I, Division 1 (501.5). - All other applicable Code rules apply to equipment and wiring in hazardous (classified) locations, except as modified by Article 504 (Intrinsically Safe Systems) and Article 505 itself (505.3).

Types of protection — 505.2 definitions - Intrinsic safety: "ia" = Zone 0, "ib" = Zone 1, "ic" = Zone 2. Associated apparatus marked [ia], [ib], or [ic] is located outside the hazardous (classified) location unless also protected by another type of protection, such as flameproof. - Encapsulation: "ma" = Zone 0, "m" or "mb" = Zone 1, "mc" = Zone 2. - Flameproof "d": enclosure withstands an internal explosion without damage and without transmitting ignition through joints or structural openings. -…

Key Concepts

Swimming pools, spas, hot tubs (Article 680) - Electric pool water heaters: heating elements subdivided into loads not exceeding 48 amperes and protected at not over 60 amperes; branch-circuit conductor ampacity and OCPD rating not less than 125 percent of total nameplate-rated load — 680.9. - General-purpose 125-volt, 15- or 20-ampere receptacle at a permanently installed pool: not less than 6 ft and not more than 20 ft from the inside wall, and not more than 6 ft 6 in. above the floor, platform, or grade — 680.22(A)(1). - Receptacles for water-pump motors/circulation and sanitation loads: at least 10 ft from inside walls; reduced to not less than 6 ft only if single, grounding type, and GFCI protected — 680.22(A)(2). - Wall-mounted wet-niche luminaire: top of lens not less than 18 in. below normal water level unless listed for lesser depths; in no case less than 4 in. — 680.23(A)(5). - Junction box for a wet-niche luminaire above the low voltage contact limit: not less than 4 in. above ground/pool deck (from…

Key Concepts

Article 800 — Communications Circuits - Unlisted outside plant communications cable may run inside a building only in spaces other than risers, ducts/plenums and other environmental air spaces, for a length from the point of entrance not exceeding 15 m (50 ft), and must terminate in an enclosure or on a listed primary protector [800.48]. Informational Note No. 2 warns 800.90(B) may require a shorter run (protector as close as practicable to the point of entrance). - Overhead communications wires/cables need vertical clearance not less than 2.5 m (8 ft) above roofs [800.44(B)]. Exception No. 2: not less than 450 mm (18 in.) above only an overhang, if not more than 1.2 m (4 ft) of service-drop passes over it and it terminates at a through- or above-the-roof raceway/approved support. Exception No. 3: not less than 900 mm (3 ft) where roof slope is not less than 100 mm in 300 mm (4 in. in 12 in.). - Supply service drops 0–750 V above and parallel to communications drops: minimum separation **300…