Idaho - ID JOURNEYMAN ELECTRICIAN EXAM

Key Concepts

Purpose and Scope of the NEC (Article 90.2) The NEC's primary purpose is "practical safeguarding of persons and property from hazards arising from the use of electricity." The Code is NOT a design specification or instruction manual for untrained persons. Compliance with the Code results in an installation that is "essentially free from hazard but not necessarily efficient, convenient, or adequate for good service."

Code Coverage (Article 90.2(C)) The NEC covers installations in: - Public and private premises (buildings, structures, mobile homes, RVs, floating buildings) - Yards, lots, parking lots, carnivals, industrial substations - Installations connecting to electricity supply - Utility buildings (offices, warehouses, garages) not integral to generating plants - Shore power installations for ships/watercraft - Vehicle-to-premises power export systems

Installations NOT Covered (Article 90.2(D)) The NEC does NOT apply to: - Ships, watercraft (except floating buildings), aircraft, automotive vehicles (except mobile homes/RVs) - Underground mining installations - Railway power systems for rolling stock operation - Communications equipment under exclusive utility control - Utility installations on utility-owned property or easements

Key Concepts

Feeder Definition & Scope (215.1) - Covers installation, overcurrent protection, minimum size, and ampacity requirements for feeders not over 1000V AC or 1500V DC - Feeders carry power from service equipment or other supply source to final branch-circuit overcurrent devices

Minimum Rating and Size Requirements (215.2) - Feeder conductors must have ampacity equal to the larger of two calculations: 1. Continuous/Noncontinuous Load Calculation: Noncontinuous load + 125% of continuous load 2. Adjustment/Correction Factor Calculation: Maximum load after applying 310.14 factors - Must comply with terminal temperature ratings per 110.14(C)

Key Exceptions for 100% Rated Equipment (215.2(A)(1) Exception 1) - If assembly and overcurrent devices are listed for 100% operation, conductors can be sized at continuous load + noncontinuous load (no 125% multiplier)

Grounded Conductor Sizing (215.2(B)) - Feeder grounded conductor cannot be smaller than equipment grounding conductor size 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 load from service conductors rated 55 amperes or less, feeder ampacity cannot be less than service conductor ampacity

Key Concepts

Article 300 Scope and Application - Article 300 covers general requirements for ALL wiring methods and materials unless specifically modified by other Chapter 3 articles. These requirements do NOT apply to conductors that are integral parts of equipment like motors or factory-assembled control equipment.

Voltage Limitations (300.2) - Wiring methods in Chapter 3 are used for systems 1000V AC or 1500V DC nominal or less. They can be used for higher voltages only where specifically permitted elsewhere in the Code.

Single Conductor Requirements (300.3(A)) - Single conductors from Table 310.4(1) are only permitted when installed as part of a recognized Chapter 3 wiring method. Exception: separate overhead conductors per 225.6.

Same Circuit Conductor Grouping (300.3(B)) - ALL conductors of the same circuit, including grounded conductors and equipment grounding conductors, must be contained within the same raceway, cable, or cord. This prevents inductive heating and ensures proper circuit operation.

Key Concepts

Article 400 Coverage and Scope (400.1-400.3) Article 400 covers general requirements, applications, and construction specifications for flexible cords and flexible cables. All flexible cords must comply with this article AND applicable provisions of other NEC articles. Flexible cords and cables must be suitable for the conditions of use and location where installed.

Cord Types and Applications (400.4) Flexible cords must conform to Table 400.4 specifications. Any cord not listed in Table 400.4 requires permission from the authority having jurisdiction. Key cord types include:

• Type C (Lamp Cord): 300V, 18-16 AWG, pendant/portable use, dry locations only, NOT hard usage
• Type S (Hard Service): 600V, 18-2 AWG, thermoset insulation, damp locations, extra-hard usage
• Type SJ (Junior Hard Service): 300V, 18-10 AWG, thermoset insulation, damp locations, hard usage
• Type SO/SOW: Oil-resistant versions for damp/wet locations
• Type G (Portable Power): 2000V, 12-500 kcmil, portable and extra-hard usage

Voltage and Usage Classifications - 300V ratings: Light-duty applications (lamp cords, junior service cords) - 600V ratings: Standard portable equipment and general use - 2000V ratings: Heavy-duty portable power applications

Key Concepts

Article 500 Classifications (NEC 500.5) Hazardous locations are classified by three main systems: - Class I: Flammable gases and vapors (gasoline, natural gas, propane) - Class II: Combustible dusts (grain dust, coal dust, metal powders) - Class III: Combustible fibers/flyings (cotton, wood shavings, textile fibers)

Each class has two divisions: - Division 1: Hazardous materials present under normal operating conditions - Division 2: Hazardous materials present only under abnormal conditions (leaks, accidents, equipment failure)

Documentation Requirements (NEC 500.4) All hazardous location designations must be documented on area classification drawings. This documentation must be available to the AHJ and authorized personnel for design, installation, inspection, maintenance, and operation.

Coverage Scope (NEC 500.1) Article 500 covers traditional Division classification but does NOT cover: - Zone classifications (Zone 0, 1, 2 for gases; Zone 20, 21, 22 for dusts) - Explosive/pyrotechnic locations - Pyrophoric materials - Non-electrical ignition sources

Individual Area Assessment (NEC 500.5(A)(1)) Each room, section, or area must be evaluated individually for classification. The presence and likelihood of flammable/combustible concentrations determines the specific classification.

What to Focus On

Key Concepts

Article 600 Scope and Coverage: Electric signs and outline lighting installations are covered regardless of voltage. This includes neon tubing, LED signs, HID lamps, fluorescent, incandescent, and electroluminescent systems (600.1).

Listing Requirements (600.3): All fixed, mobile, or portable electric signs, outline lighting, and retrofit kits must be listed and labeled with installation instructions. Key exceptions: field-installed skeleton tubing and outline lighting systems using listed luminaires wired per Chapter 3 are not required to be listed as complete systems.

Required Branch Circuit (600.5(A)): Every commercial building and commercial occupancy accessible to pedestrians must have at least one outlet at each entrance for sign use. This outlet must be supplied by a dedicated 20-ampere branch circuit that serves no other load. Exceptions include delivery/service entrances and loads directly related to sign control.

Branch Circuit Ratings (600.5(C)): - Neon signs: Maximum 30 amperes - All other signs: Maximum 20 amperes - All sign circuits are considered continuous loads for calculation purposes

Disconnecting Means (600.6): Each sign must have an externally operable disconnect that opens all ungrounded conductors and controls no other load. Exceptions: exit directional signs within buildings and cord-connected signs with attachment plugs don't require disconnects.

Key Concepts

Classification System (Article 500) Hazardous locations are classified by three main factors: - Class: Type of hazardous material (I = gases/vapors, II = dusts, III = fibers/flyings) - Division: Likelihood of hazardous concentration (1 = normal conditions, 2 = abnormal conditions) - Group: Specific material properties for equipment selection

Article 500 Scope (500.1) - Covers Classes I, II, and III, Divisions 1 and 2 locations - Does NOT cover Zone classifications (0, 1, 2, 20, 21, 22) - Excludes explosives, pyrotechnics, and blasting agents - Excludes non-electrical ignition sources (mechanical sparks, hot surfaces)

Documentation Requirements (500.4) All classified areas must have: - Area classification drawings - Associated documentation available to AHJ - Documentation accessible to design, install, inspect, maintain, and operate personnel

Classification Determination (500.5) Each room, section, or area must be individually evaluated based on: - Properties of hazardous materials present - Likelihood of flammable/combustible concentrations - Normal vs. abnormal operating conditions

Class Definitions: - Class I: Flammable gases, flammable liquid vapors, combustible liquid vapors - Class II: Combustible dusts - Class III: Combustible fibers/flyings or ignitible fibers/flyings