Texas - Journeyman Lineman Electrician

Key Concepts

NEC Article 90 - Introduction and Foundation The National Electrical Code (NEC) Article 90 establishes the foundational principles you must understand. According to Section 90.2(A), the Code's primary purpose is "the practical safeguarding of persons and property from hazards arising from the use of electricity." This is not a design manual but a safety standard.

Code Coverage and Scope (90.2(C)) The NEC covers installation and removal of: - Electrical conductors, equipment, and raceways - Signaling and communications conductors and equipment - Optical fiber cables - Installations on public/private premises, yards, industrial substations - Shore power installations for watercraft - Vehicle-to-grid connections

Critical Exclusions (90.2(D)) Know what the NEC does NOT cover: - Ships and watercraft (except floating buildings) - Railway rolling stock and aircraft - Automotive vehicles (except mobile homes/RVs) - Underground mines and mobile mining equipment - Electric utility installations under exclusive utility control

Key Concepts

Article 220 - Load Calculations Scope This article provides the foundation for calculating branch-circuit, feeder, and service loads. Understanding the organization is critical: - Part I: General requirements - Part II: Branch-circuit loads - Part III & IV: Feeder and service loads - Parts V-VII: Special occupancies (farms, healthcare, marinas)

Voltage Standards (NEC 220.5(A)) Unless otherwise specified, use these nominal system voltages for load calculations: - 120V, 120/240V, 208Y/120V, 240V - 347V, 480Y/277V, 480V - 600Y/347V, 600V

Amperage Calculations (NEC 220.5(B)) Decimal fractions smaller than 0.5 are dropped; 0.5 and above round up to the nearest whole ampere.

Floor Area Calculations (NEC 220.5(C)) Calculate from outside dimensions of the building. For dwelling units, exclude open porches and unfinished areas not adaptable for future habitable use.

Key Concepts

Scope and Definition (215.1) - Article 215 covers feeders not exceeding 1000V AC or 1500V DC - For feeders over these voltages, refer to Article 235 Part III

Minimum Conductor Sizing (215.2) Feeder conductors must meet the larger of two requirements:

1. Load-Based Sizing (215.2(A)(1)): Ampacity ≥ noncontinuous load + 125% of continuous load
2. Exception: If assembly is listed for 100% operation, ampacity can equal total load (continuous + noncontinuous)

3. Exception: Grounded conductors not connected to overcurrent devices can be sized at 100% of total load

4. Adjustment/Correction Factor Sizing (215.2(A)(2)): Must account for derating per 310.14

Grounded Conductor Sizing (215.2(B)) - Minimum size cannot be smaller than equipment grounding conductor per 250.122 - Exception: 250.122(F) doesn't apply when grounded conductors run in parallel

Service Conductor Relationship (215.2(C)) - When feeder carries total service load and service conductors are 55A or less, feeder ampacity must equal or exceed service conductor ampacity

Key Concepts

Grounded Conductor Identification (Article 200) - 6 AWG or smaller (200.6(A)): Must be identified by continuous white or gray outer finish, three continuous white/gray stripes on non-green insulation, or white/gray with colored tracer threads - 4 AWG or larger (200.6(B)): Same options as smaller conductors, plus permitted to be marked white/gray at terminations during installation - Different voltage systems (200.6(D)): When grounded conductors of different nominal voltage systems are in same enclosure, each must be identified by voltage system with documentation readily available

Grounded Conductor Installation Requirements (Article 200.2-200.4) - Insulation rating (200.2(A)): For systems ≤1000V, insulation must be suitably rated for any ungrounded conductor of same circuit - Continuity (200.2(B)): Cannot depend on connection to metal enclosure, raceway, or cable armor - System connection (200.3): Must be electrically connected to supply system grounded conductor for common continuous grounded system - Neutral usage (200.4(A)): Cannot be used for more than one branch circuit, multiwire branch circuit, or feeder set unless specifically permitted

Key Concepts

Article 300 Scope and Application - Article 300 covers general requirements for ALL wiring installations unless modified by other Chapter 3 articles - Does NOT apply to conductors that are integral parts of equipment (motors, controllers, factory-assembled equipment) - Applies to systems 1000V AC or 1500V DC and below, unless specifically permitted for higher voltages elsewhere

Metric Designators and Trade Sizes (Table 300.1(C)) - Conduit sizing uses both metric designators and trade sizes for identification - Key sizes: 16 (1/2"), 21 (3/4"), 27 (1"), 35 (1¼"), 41 (1½"), 53 (2") - These are identification purposes only - NOT actual dimensions

Conductor Installation Rules (300.3) - Single conductors from Table 310.4(1) must be part of a recognized Chapter 3 wiring method - Critical Rule: All conductors of the same circuit, grounded conductor, equipment grounding conductors, and bonding conductors must be in the same raceway/cable/conduit body - Exception for overhead conductors per 225.6

Key Concepts

Scope and Application (404.1) - Article 404 covers all switches, switching devices, and circuit breakers used as switches operating at 1000V and below - Does NOT cover wireless control equipment without circuit conductor connections

Switch Connection Requirements (404.2) - Three-way and four-way switches: All switching must be done only in the ungrounded (hot) conductor - Grounded conductor protection: Switches/circuit breakers SHALL NOT disconnect the grounded conductor, except when all conductors are disconnected simultaneously - Lighting control circuits (404.2(C)): Grounded conductor must be installed at switch locations controlling lighting in bathrooms, hallways, stairways, and habitable rooms - Exception: Not required for replacement switches in existing locations where grounded conductor cannot be extended without removing finish materials - Electronic switch limitations: Maximum 5 per branch circuit, 25 per feeder

Enclosure Requirements (404.3) - Switches must be externally operable type in listed enclosures - Minimum wire-bending space per 312.6 - Enclosures SHALL NOT be used as junction boxes or raceways unless complying with 312.8

Key Concepts

Article 430 - Motors, Motor Circuits, and Controllers: This is the primary NEC article governing motor installations. Per Table 240.3, motors must be protected according to Article 430, not general overcurrent rules in Article 240.

Motor Overcurrent Protection Requirements: Motors require multiple levels of protection: - Branch-circuit short-circuit and ground-fault protection (typically fuses or circuit breakers) - Motor overload protection (to protect the motor windings from overheating) - Motor circuit conductor protection (sized according to motor full-load current)

Motor Full-Load Current (FLC): Always use NEC tables for motor FLC, not nameplate values, when sizing conductors and overcurrent protection. Nameplate values are only used for overload protection calculations.

Article 445 - Generators: Generators have specific overcurrent protection requirements separate from motors. Generator conductors must be protected according to their ampacity, and generators require overcurrent protection on both the generator side and load side of the installation.

Key Concepts

Service Disconnecting Means Requirements (Article 230, Part VI) - Service disconnecting means must be readily accessible and located at a readily accessible location either outside the building or inside nearest the service entrance point - Maximum of six switches/breakers per service (230.71(A)) - Each service disconnect must be permanently marked to identify the load served - Service disconnects must have adequate interrupting capacity for available fault current

Identification and Marking (230.2(E), 230.70(B)) - Buildings with multiple services require permanent plaques identifying all services, feeders, and branch circuits - Service disconnects must be legibly marked to indicate their purpose - Emergency disconnects must be clearly identified

Service Location and Accessibility (230.70) - Service disconnecting means shall be installed at a readily accessible location - Must be either outside the building or inside nearest the point of service conductor entrance - Cannot be installed in bathrooms or other prohibited locations - Working space requirements per Article 110 must be maintained