ICC G16 Master Electrician Exam (2017 NEC)

(2017 NEC)

Key Concepts

NEC Purpose, Scope, and Arrangement (Article 90) - Purpose: "the practical safeguarding of persons and property from hazards arising from the use of electricity." The Code "is not intended as a design specification or an instruction manual for untrained persons" (90.1(A)). - Covered (90.2(A)): "the installation and removal of electrical conductors, equipment, and raceways; signaling and communications conductors, equipment, and raceways; and optical fiber cables and raceways." - Not covered (90.2(B)(1)): installations in ships, watercraft other than floating buildings, railway rolling stock, aircraft, or automotive vehicles other than mobile homes and recreational vehicles. - Code arrangement (90.3): Chapters 1–4 apply generally; Chapters 5, 6, and 7 apply to special occupancies, equipment, or conditions and may supplement or modify Chapters 1 through 7. Chapter 8 (communications) is not subject to Chapters 1–7 except where specifically referenced. Chapter 9 consists of tables applicable as referenced. - Enforcement (90.4): "The authority having jurisdiction…

Key Concepts

Number of services and identification - A building is supplied by only one service unless permitted otherwise. Additional services are permitted without special permission where capacity requirements exceed 2000 amperes at a supply voltage of 1000 volts or less — NEC 230.2(C)(1). - Additional services are also permitted for fire pumps, emergency systems, legally required standby, optional standby, parallel power production, and systems designed for multiple sources for enhanced reliability — 230.2(A). - Where a building is supplied by more than one service (or a combination of branch circuits, feeders, and services), a permanent plaque or directory must be installed at each service disconnect location — 230.2(E).

Key Concepts

Scope (215.1). Article 215 covers installation requirements, overcurrent protection, minimum size, and ampacity of feeder conductors. Article 225 covers outside branch circuits and feeders run on or between buildings, structures, or poles, including supply conductors between a dwelling unit and a detached garage.

Feeder conductor sizing (215.2(A)(1), Handbook pp. 90–91). Feeder conductors must have an ampacity not less than required to supply the load calculated in Parts III, IV, and V of Article 220, and must be sized for the larger of: - (a) noncontinuous load plus 125 percent of the continuous load, or - (b) the maximum load to be served after application of any adjustment or correction factors.

Key Concepts

Overcurrent protection of conductors (Art. 240, Part I) - Conductors must be protected per their ampacities in 310.15 unless 240.4(A)–(G) permits otherwise (240.4). - 240.4(B): the next higher standard OCPD rating above conductor ampacity is permitted only if all three conditions are met, including (1) the conductors are not part of a branch circuit supplying more than one receptacle for cord-and-plug-connected portable loads, and (3) the next higher standard rating does not exceed 800 amperes (Handbook pp. 149–150). - 240.4(C): where the OCPD is rated over 800 amperes, conductor ampacity must be equal to or greater than the device rating. - 240.4(D) Small Conductors (applied after ambient and conductor-count correction): 18 AWG Cu — 7 A (continuous loads ≤ 5.6 A; branch-circuit-rated CB or fuse listed/marked for 18 AWG Cu, or Class CC, J, or T fuses); 16 AWG Cu — 10 A; 14 AWG Cu — 15 A (240.4(D)(3), p. 150).…

Based on the 2017 NEC

Key Concepts

Securing and supporting (memorize these distances): - EMT (358.30(A)): securely fastened at intervals not exceeding 3 m (10 ft), and within 900 mm (3 ft) of each outlet box, junction box, device box, cabinet, conduit body, or other tubing termination. - RMC (344.30(A)(1)): secured within 900 mm (3 ft) of each termination; may be increased to 1.5 m (5 ft) where structural members do not readily permit fastening within 3 ft (344.30(A)(2)). Supports at intervals not exceeding 3 m (10 ft), or per Table 344.30(B)(2) for threaded-coupling straight runs. - PVC (352.30(A)): securely fastened within 900 mm (3 ft) of each termination; supports per Table 352.30. - FMC (348.30(A)) and LFMC (350.30(A)): securely fastened within 300 mm (12 in.) of each box, cabinet, conduit body, or other conduit termination, and supported/secured at intervals not to exceed 1.4 m (4½ ft). Horizontal runs through framing openings at intervals…

Key Concepts

Luminaires (Article 410) - Luminaires shall be constructed, installed, or equipped with shades or guards so combustible material is not subjected to temperatures over 90°C (194°F) — 410.11 (Handbook p. 449). - Lampholders over highly combustible material must be the unswitched type; unless an individual switch is provided for each luminaire, they must be at least 2.5 m (8 ft) above the floor or located/guarded so lamps cannot be readily removed or damaged — 410.12. - Bathtub/shower zone: no cord-connected, chain-, cable-, or cord-suspended luminaires, lighting track, pendants, or ceiling-suspended (paddle) fans within 900 mm (3 ft) horizontally and 2.5 m (8 ft) vertically from the top of the bathtub rim or shower stall threshold — 410.10(D) (pp. 449–450). - Under metal-corrugated sheet roof decking: not less than 38 mm (1½ in.) from the lowest surface of the decking to the top of the luminaire — 410.10(F). - Clothes closets — 410.16:…

2017 NEC

Key Concepts

Motor disconnecting means — ampere rating (430.110) - General: not less than 115 percent of the motor full-load current rating for circuits rated 1000 volts, nominal, or less — 430.110(A). - Torque motors: at least 115 percent of the motor nameplate current — 430.110(B). - Combination loads: ampere rating not less than 115 percent of the sum of all currents at the full-load condition determined per 430.110(C)(1) — 430.110(C)(2). Locked-rotor values (Table 430.251(A)/(B)) establish the horsepower rating, not the ampere rating.

Disconnect location (430.102) - Controller: an individual disconnecting means for each controller, located in sight from the controller location — 430.102(A). - Motor: disconnect in sight from the motor and the driven machinery location — 430.102(B)(1); the controller disconnect may serve as the motor disconnect if in sight from both — 430.102(B)(2). - Exception to (B)(1) and (B)(2): the motor disconnect may be omitted where its location is impracticable…

Key Concepts

Use the table values, not the nameplate (430.6(A)(1)). For general motor applications, the values in Table 430.247 through Table 430.250 are used to determine conductor ampacity and the ampere ratings of switches and branch-circuit short-circuit and ground-fault (BCSCGF) protection, instead of the actual nameplate current. Exception: separate motor overload protection is based on the motor nameplate current rating, 430.6(A)(2).

Branch-circuit conductors — 125% (430.22). Conductors supplying a single continuous-duty motor must have an ampacity of not less than 125 percent of the motor full-load current as determined by 430.6(A)(1) (Ugly's, pp. 41–42).

Special conductor multipliers. - Wye-start, delta-run: line side 125%; between controller and motor, not less than 72 percent of FLC (58% × 1.25) — 430.22(C) (NEC, p. 502). - Part-winding: line side 125%; controller to motor 62.5% (50% × 1.25) — 430.22(D). - DC motor-rectifier supplied, 430.22(A): single-phase half-wave 190%, full-wave 150%; rectifier input conductors 125% of rated input current…

Key Concepts

Class definitions (Article 500). Class I, Division 2 covers locations where flammable gases or liquid-produced vapors are normally confined within closed containers or closed systems and can escape only in case of accidental rupture, breakdown, or abnormal equipment operation [500.5(B)(2)]. Class II locations are hazardous because of combustible dust; the Informational Note to 500.5(C)(1) warns that dusts containing magnesium or aluminum (Group E) are "particularly hazardous," requiring extreme precaution. Class III locations are hazardous due to easily ignitible fibers or combustible flyings not likely to be in suspension [500.5(D); 503.1 — typically textile mills and woodworking plants]. Refrigerant machinery rooms with ammonia systems may be unclassified where mechanical ventilation runs continuously or is initiated by detection at a concentration not exceeding 150 ppm [500.5(A)].