Texas Residential Wireman Electrician

Texas Residential Wireman Electrician

Key Concepts

Code arrangement and enforcement - The 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 general requirements (90.3). - Chapter 8 covers communications systems and is not subject to Chapters 1 through 7 except where specifically referenced; Chapter 9 consists of tables applicable as referenced (90.3). - The Code is intended to be suitable for mandatory application by governmental bodies exercising legal jurisdiction over electrical installations, including signaling and communications systems, and for use by insurance inspectors (90.4(A)). - Mandatory rules use shall or shall not; permissive rules use shall be permitted or shall not be required (90.5(A), (B)). Informational notes and informative annexes…

Key Concepts

Overhead service clearances - Overhead service conductors need not less than 2.6 m (8 ft 6 in.) vertical clearance above a roof, maintained for 900 mm (3 ft) in all directions from the roof edge — 230.24(A). - Where voltage between conductors does not exceed 300 and roof slope is 4 in. in 12 in. or greater, clearance may drop to 900 mm (3 ft) — 230.24(A), Exception No. 2. - Over a roof overhang, ≤300 V, clearance may drop to 450 mm (18 in.) if not more than 1.8 m (6 ft) of conductors (1.2 m / 4 ft horizontally) pass above the overhang and they terminate at a through-the-roof raceway or approved support — 230.24(A), Exception No. 3. - Open conductors or multiconductor cable without an overall jacket: 900 mm (3 ft) from openable windows,…

Texas Residential Wireman Electrician · 7 questions (9% of exam)

Key Concepts

Minimum conductor ampacity. Feeder conductors must have an ampacity not less than the larger of the continuous/noncontinuous calculation or the adjusted/corrected load, and comply with 110.14(C) (NEC 215.2(A), 2026: 215.4(A)). 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 (215.2(A)(1) / 2026 215.4(A)(1)).

Three exceptions permit 100% sizing: - Exc. 1 — assembly, including the OCPDs, listed for operation at 100 percent of its rating. - Exc. 2 — a portion of a feeder connected at both supply and load ends to separately installed pressure connections per 110.14(C)(2); no portion may extend into an enclosure containing feeder supply or load terminations (110.14(C)(1)).…

Key Concepts

• Continuous/noncontinuous sizing. Branch-circuit conductors must have ampacity not less than the noncontinuous load plus 125 percent of the continuous load (210.19(A)(1)), and the overcurrent device rating shall not be less than the noncontinuous load plus 125 percent of the continuous load (210.20(A)). The same 125 percent rule applies to feeders (215.2(A)(1)). Exception: if the assembly, including the overcurrent devices, is listed for operation at 100 percent of its rating, ampacity may be the sum of continuous plus noncontinuous load (215.2(A)(1), Exception No. 1; parallel exception in 210.19(A)).
• Minimum sizes and OCPD caps. Branch-circuit conductors for other loads shall not be smaller than 14 AWG (210.19(D)). Maximum overcurrent protection: 18 AWG copper 7 amperes where continuous loads do not exceed 5.6 amperes (240.4(D)(1)), 12 AWG copper 20 amperes (240.4(D)(6)), 10 AWG copper 30 amperes (240.4(D)(8)). -…

Key Concepts

Scope and voltage. Chapter 3 wiring methods are used for 1000 volts AC, 1500 volts DC, nominal, or less where not specifically limited [300.2(A)].

Physical protection (300.4). - Bored holes in joists, rafters or wood members: hole edge not less than 32 mm (1¼ in.) from the edge of the wood member; where that distance cannot be maintained, protect with a steel plate at least 1.6 mm (1/16 in.) thick [300.4(A)(1)]. - Notches in wood members: steel plate at least 1.6 mm (1/16 in.) thick installed to cover the area of the wiring before the building finish is applied [300.4(A)(2)]. Exception No. 1 exempts rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit and electrical metallic tubing. - Metal framing members: where nails or screws are likely to penetrate NM cable or ENT, a steel sleeve, plate…

Key Concepts

Switches - An ac or dc general-use snap switch may control inductive loads not exceeding 50 percent of the switch's ampere rating at the applied voltage — NEC 404.14(B). - A general-use ac snap switch (not ac‑dc) used as a controller for a stationary motor rated 2 hp or less, 300 volts or less, requires the motor full-load current to be not more than 80 percent of the switch ampere rating — NEC 430.83(C). - A general-use switch used as the disconnecting means for a stationary motor 2 hp or less, 300 volts or less, must be rated not less than twice the motor full-load current — NEC 430.109(C).

Key Concepts

Motor branch-circuit conductors. Conductors supplying a single motor 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) (NEC 430.22). Feeder conductors supplying several motors are sized per 430.24: 125% of the largest motor's FLC plus the sum of the other motors' FLCs.

Determining FLC. For general motor applications, the values in Table 430.247 through Table 430.250 are used instead of the nameplate current to determine conductor ampacity, switch ratings, and branch-circuit short-circuit and ground-fault protection (430.6(A)(1)). Nameplate current is used for separate motor overload protection (430.6(A)(2)).

Key Concepts

Switch connections (Article 404.2) - Three-way and four-way switches shall be wired so that all switching is done only in the ungrounded circuit conductor. Where in metal raceways or metal-armored cables, wiring between switches and outlets follows 300.20(A). Exception: switch loops do not require a grounded conductor. — 404.2(A) - Switches or circuit breakers shall not disconnect the grounded conductor, unless all circuit conductors are disconnected simultaneously, or the device is arranged so the grounded conductor cannot be disconnected until all ungrounded conductors are. — 404.2(B) - A grounded circuit conductor must be installed where switches control lighting loads supplied by a grounded general-purpose branch circuit serving bathrooms, hallways, stairways, and habitable rooms or occupiable spaces. Not required where conductors enter through a raceway large enough for all conductors including a grounded conductor, where snap switches have…

Key Concepts

Location classification - Class I: flammable gases/vapors in quantities sufficient to produce explosive or ignitible mixtures. Class I, Division 1 = ignitible concentrations exist under normal operating conditions — NEC 500.5(B)(1). Inadequately ventilated areas within spraying or coating operations using volatile flammable fluids are listed as typical Div 1 — 500.5(B)(1) Informational Note. - Class II, Division 1 = combustible dust in the air under normal operating conditions in quantities sufficient to produce explosive or ignitible mixtures — 500.5(C)(1). - Class III, Division 1 = locations where ignitible fibers/flyings are handled, manufactured, or used (rayon, cotton, and other textile mills) — 500.5(D)(1). - Ammonia refrigerant machinery rooms may be unclassified where mechanical ventilation operates continuously or is initiated by a detection system at a concentration not exceeding 150 ppm — 500.5(A)(2).

Texas Residential Wireman Electrician | 2 questions (2% of exam) Subtopics: Photovoltaics, Electric Vehicle Chargers

Key Concepts

Photovoltaics — Voltage Limits

• Maximum PV dc voltage on or in one- and two-family dwellings: 600 volts. PV system dc circuits shall not exceed 1000 volts within or originating from arrays located on or attached to buildings and inside buildings, but shall not exceed 600 volts on or in one- and two-family dwellings (NEC 690.7).
• Maximum voltage is the highest voltage between any two conductors of a circuit or any conductor and ground (NEC 690.7).
• A permanent, readily visible label indicating the highest maximum dc voltage must be provided at the dc PV disconnecting means, the PV electronic power conversion equipment, or associated distribution equipment (NEC 690.7(D)).