## Basic Electrical Definitions

• Voltage (V): The electrical potential difference or electromotive force, measured in volts. It's the 'push' that makes current flow.
• Current (I): The flow of electrons through a conductor, measured in amperes (amps). It's the 'amount' of electricity flowing.
• Resistance (R): The opposition to the flow of current, measured in ohms (Ω). Materials with high resistance are insulators; low resistance are conductors.
• Power (P): The rate at which electrical energy is consumed or produced, measured in watts (W). It represents the work done by electricity.
• Conductor: A material that allows electric current to flow easily (e.g., copper, aluminum).
• Insulator: A material that resists the flow of electric current (e.g., rubber, plastic, glass).
• Ampacity: The maximum current in amperes that a conductor can carry continuously under specific conditions without exceeding its temperature rating.
• Overcurrent Protection Device (OCPD): A device, such as a circuit breaker or fuse, designed to automatically open a circuit when the current exceeds a predetermined safe level, protecting conductors and equipment.
• Grounding: The process of connecting an electrical system or equipment to the earth to provide a safe path for fault currents and limit voltage.
• Bonding: The permanent joining of metallic parts to form an electrically conductive path that ensures electrical continuity and the capacity to safely conduct any fault current likely to be imposed.

## Fundamental Electrical Laws and Calculations

• Ohm's Law: The foundational relationship between voltage, current, and resistance.
• V = I x R (Voltage = Current x Resistance)
• I = V / R (Current = Voltage / Resistance)
• R = V / I (Resistance = Voltage / Current)
• Power Law: Relates power to voltage and current.
• P = V x I (Power = Voltage x Current)
• Other forms: P = I² x R and P = V² / R
• Series Circuits: Components are connected end-to-end, forming a single path for current.
• Current (I) is the same throughout the circuit.
• Total Resistance (Rt) = R1 + R2 + ...
• Total Voltage (Vt) = V1 + V2 + ... (sum of individual voltage drops).
• Parallel Circuits: Components are connected across the same two points, providing multiple paths for current.
• Voltage (V) is the same across all branches.
• Total Current (It) = I1 + I2 + ... (sum of currents in each branch).
• Total Resistance (Rt) = 1 / (1/R1 + 1/R2 + ...) (for two resistors, Rt = (R1 x R2) / (R1 + R2)).

## Electrical Theory and Safety

• AC (Alternating Current): Electrical current that periodically reverses direction. This is the primary form of power supplied to homes and businesses.
• DC (Direct Current): Electrical current that flows in only one direction. Commonly found in batteries and electronic devices.
• National Electrical Code (NEC): The benchmark for safe electrical design, installation, and inspection to protect persons and property from electrical hazards. Texas Journeyman Electricians must adhere to the NEC.
• Voltage Drop: The reduction in electrical potential along the length of a conductor due to its resistance. Excessive voltage drop can lead to inefficient operation and damage to equipment.

## Services and Service Equipment

Services refer to the conductors and equipment that deliver electricity from the utility supply to the building's wiring system. The service point is the demarcation between utility and premises wiring. Service conductors are categorized as service-drop (overhead) or service-lateral (underground).

Service equipment consists of the main control and cutoff for the electrical supply. This typically includes a main circuit breaker(s) or switch(es) and fuses. Key requirements for service equipment include:

• Location: The service disconnect must be installed at a readily accessible location, either outside or inside the building, nearest the point of entrance of the service conductors.
• Number of Disconnects: A maximum of six main disconnects are permitted to serve as the service disconnect for a single service, grouped in one location.
• Rating: The service disconnect must have an ampere rating sufficient to carry the load.
• Identification: Each service disconnect must be permanently marked to identify it as a service disconnect.
• Working Space: Adequate working space must be maintained in front of the service equipment (NEC 110.26).

Grounding and Bonding for Services: Essential for safety and proper operation.

• Main Bonding Jumper: Required to connect the equipment grounding conductor(s) and the service-disconnect enclosure to the grounded service conductor (neutral) at the service entrance.
• Grounding Electrode Conductor (GEC): Connects the grounded service conductor (neutral) and the equipment grounding conductor(s) to the grounding electrode system.
• Grounding Electrode System: Must be established at each service, typically utilizing a metal underground water pipe, building steel, concrete-encased electrodes, or ground rods.

## Separately Derived Systems (SDS)

A separately derived system is an electrical source, such as a transformer, generator, or solar PV system, that has no direct electrical connection to the circuit conductors of any other electrical source other than through grounding and bonding connections. These systems essentially create a new electrical source within a premises.

Grounding and Bonding for SDS: Crucial for safety and fault clearing.

• System Bonding Jumper: Required to connect the grounded conductor (neutral) of the SDS to its equipment grounding conductor(s) and the metal enclosure of the first disconnecting means or overcurrent device. This establishes the first connection to ground for the SDS.
• Grounding Electrode Conductor (GEC) for SDS: Connects the grounded conductor of the SDS to a grounding electrode system for the SDS. This system can be an existing one or a newly installed one, ensuring proper earthing for the new source.
• Overcurrent Protection: SDS must have appropriate overcurrent protection for its output conductors.

Understanding the distinction between service grounding/bonding and SDS grounding/bonding is vital for compliance and safety. The service is the utility connection, while an SDS creates an independent source within the premises.

## Understanding Feeders

A feeder is defined in NEC Article 100 as all circuit conductors between the service equipment, the source of a separately derived system, or other power supply and the final branch-circuit overcurrent device. Essentially, feeders carry power from the main service panel to subpanels or other distribution points, but not directly to individual loads. Their primary purpose is to distribute power efficiently and safely within a building or facility.

## Feeder Sizing

Accurate feeder sizing is critical for safety and performance. It involves several steps, primarily guided by NEC Article 215 and Article 220.

• Load Calculations: Determine the total connected load. Loads are categorized as continuous (expected to operate for 3 hours or more) or non-continuous. Continuous loads must be calculated at 125% of their rating for sizing conductors and overcurrent devices, unless the assembly is listed for 100% operation (NEC 215.2(A)(1), 210.19(A)(1)).
• Demand Factors: For many occupancies (e.g., dwelling units, commercial kitchens), the NEC permits the application of demand factors (NEC Article 220, Parts III and IV). These factors acknowledge that not all loads will operate simultaneously or at full capacity, allowing for smaller, more economical feeder sizes while maintaining safety.
• Conductor Ampacity: Once the adjusted load is determined, select conductors from NEC Table 310.16 (or other relevant tables) based on the wire material (copper or aluminum), insulation type, and ambient temperature.
• Voltage Drop: While not a mandatory NEC requirement for minimum conductor size, the FPNs in NEC 215.2(A)(4) recommend that the maximum total voltage drop for feeders and branch circuits combined not exceed 5%, with 3% for the feeder itself, to ensure efficient operation of equipment.

## Feeder Overcurrent Protection

Feeders must be protected against overcurrent by an appropriately sized overcurrent protective device (OCPD), such as a circuit breaker or fuse, as per NEC Article 240 and 215.3.

• Rating: The OCPD must have a rating not greater than the ampacity of the feeder conductors, with specific exceptions (e.g., motor circuits, small conductors per NEC 240.4). Standard overcurrent device ratings are found in NEC 240.6(A).
• Location: The OCPD must be located at the supply end of the feeder, or at a point where the conductor size is reduced, unless specific tap rules apply (NEC 240.21).

Understanding these principles ensures feeders are installed safely and reliably, meeting the requirements of the NEC.

## Branch Circuits and Conductors: Key Concepts

Understanding branch circuits and conductors is fundamental for the Journeyman Electrician Exam. A branch circuit is the circuit conductors between the final overcurrent protective device and the outlets.

Conductor Sizing and Ampacity

Conductor sizing is critical for safety and efficiency. The ampacity of a conductor is the maximum current, in amperes, that it can continuously carry under the conditions of use without exceeding its temperature rating.

• NEC Table 310.16 is the primary reference for conductor ampacity for copper and aluminum conductors rated up to 2000V.
• Correction Factors: Ampacity must be adjusted for ambient temperature (when exceeding 86°F or 30°C) and for the number of current-carrying conductors in a raceway or cable (more than three). These factors reduce the allowable ampacity.
• Overcurrent Protection: The overcurrent device (e.g., circuit breaker or fuse) protects the conductor from excessive current. Generally, the overcurrent device rating must not exceed the conductor's ampacity (NEC 240.4). Smaller conductors (14, 12, 10 AWG) have specific overcurrent protection limits: 14 AWG (15A), 12 AWG (20A), 10 AWG (30A), unless specific exceptions apply.

Branch Circuit Requirements

• General Purpose Branch Circuits: Supply two or more receptacles or outlets for lighting and appliances.
• Appliance Branch Circuits: Supply energy to one or more outlets to which appliances are connected, with no permanently connected luminaires.
• Individual Branch Circuits: Supply only one piece of utilization equipment.
• Receptacle Outlets: Spacing requirements mandate that no point along the wall line in any room be more than 6 feet from a receptacle outlet (NEC 210.52).
• GFCI Protection (Ground-Fault Circuit Interrupter): Required in specific locations to protect against ground faults, such as bathrooms, garages, outdoors, kitchens (countertop receptacles), basements, and laundry areas (NEC 210.8).
• AFCI Protection (Arc-Fault Circuit Interrupter): Required for most 15A and 20A 120V branch circuits supplying outlets or devices in dwelling unit bedrooms, family rooms, dining rooms, living rooms, parlors, libraries, dens, sunrooms, recreation rooms, closets, hallways, and similar rooms (NEC 210.12).

Conductor Identification

• Grounded Conductor (Neutral): White or natural gray.
• Equipment Grounding Conductor: Green, green with yellow stripe, or bare.
• Ungrounded Conductors (Hot):: Any color other than white, gray, green, or bare.

## Wiring Methods and Materials: Key Concepts for the Journeyman Exam

The "Wiring Methods and Materials" section of the Journeyman Electrician Exam in Texas heavily relies on the National Electrical Code (NEC), specifically Chapter 3 and related articles. Understanding the appropriate use, installation, and limitations of various wiring methods is crucial.

## Common Wiring Methods

• Nonmetallic-Sheathed Cable (Type NM-B): Often called "Romex®," this cable is primarily permitted in normally dry locations (NEC 334.10(1)). It must be protected from physical damage and supported within 12 inches of boxes and at intervals not exceeding 4 1/2 feet (NEC 334.30). It is not permitted in wet or damp locations, or where exposed to corrosive fumes.
• Metal-Clad Cable (Type MC): This cable offers good physical protection and often includes an integral grounding conductor. It is permitted in most locations, including wet locations, direct burial, and hazardous locations when listed for such use (NEC 330.10). It's flexible and commonly used in commercial and industrial applications.
• Electrical Metallic Tubing (EMT): A lightweight, thin-walled raceway, EMT is suitable for exposed or concealed work in dry and damp locations (NEC 358.10). It must be supported within 3 feet of each box, cabinet, or termination, and then at intervals not exceeding 10 feet (NEC 358.30(A)). Bends must be made so that the conduit is not damaged, and the total number of 90-degree bends in a run between pulling points cannot exceed four (360 degrees total) (NEC 358.26).
• Rigid Metal Conduit (RMC): A heavy-duty, thick-walled raceway, RMC is suitable for all atmospheric conditions and occupancies, including hazardous locations when listed (NEC 344.10). It provides excellent physical protection and is often used outdoors or in demanding environments. Support requirements are typically within 3 feet of each termination and every 10 feet (NEC 344.30(A)).
• Flexible Metal Conduit (FMC) & Liquidtight Flexible Metal Conduit (LFMC): These are used where flexibility is required, such as for motor connections or to accommodate vibration. LFMC is specifically designed for wet locations and outdoor use (NEC 350.10).

## General Requirements and Materials

• Conductors (Article 310): Understand conductor sizing, insulation types (e.g., THHN, THWN, XHHW), and ampacity tables. All conductors of the same circuit, including the grounding or bonding conductor, must be contained within the same raceway, cable, or trench (NEC 300.3(B)).
• Boxes and Enclosures (Article 314): Proper box fill calculations are critical to prevent overcrowding and ensure safety. All conductors, devices, and fittings within a box contribute to the fill volume (NEC 314.16).
• Support and Protection (Article 300): All wiring methods must be adequately supported and protected from physical damage. Minimum cover requirements for underground installations are also covered here.
• Grounding and Bonding (Article 250): While a separate topic, proper grounding and bonding conductors are integral to safe wiring methods and material selection.

## Overcurrent Protective Devices (OCPDs)

Overcurrent Protective Devices (OCPDs) are essential safety components designed to protect conductors and equipment from excessive current. They include fuses and circuit breakers. OCPDs must be readily accessible and sized appropriately for the circuit's ampacity and the connected load, as per NEC Article 240.

• Fuses: Single-use devices that melt and open a circuit when current exceeds their rating. They offer excellent short-circuit protection and come in various types (e.g., time-delay, fast-acting).
• Circuit Breakers: Reusable devices that trip and open a circuit automatically upon overcurrent. They can be reset manually. Common types include Standard (Thermal-Magnetic), Ground-Fault Circuit Interrupters (GFCIs), and Arc-Fault Circuit Interrupters (AFCIs).
• GFCI: Protects against ground faults, typically required in wet or outdoor locations (e.g., bathrooms, kitchens, garages, outdoors, unfinished basements).
• AFCI: Protects against dangerous arc faults, required in most dwelling unit living areas (e.g., bedrooms, family rooms, dining rooms).

## Switches

Switches are used to make, break, or change the connections in an electrical circuit.

• Disconnecting Means: Required for all motors, appliances, and many other pieces of equipment to safely isolate them for maintenance or repair. Must be readily accessible and within sight of the equipment, or lockable in the open position.
• General-Use Switches: Designed for general switching of resistive loads not exceeding their ampere rating.
• Motor-Circuit Switches: Rated in horsepower and specifically designed for motor loads, which have high inrush currents.
• Snap Switches: Commonly used for lighting control. Must be connected such that the grounded conductor (neutral) is not switched.

## Receptacles

Receptacles provide a point of connection for portable electrical equipment.

• Grounding: All 15A and 20A, 125V receptacles must be of the grounding type and connected to an equipment grounding conductor.
• GFCI Protection: Required for 125-volt, single-phase, 15- and 20-ampere receptacles in specific locations like bathrooms, garages, outdoors, kitchens, basements, and laundry areas.
• AFCI Protection: Required for 120-volt, single-phase, 15- and 20-ampere branch circuits supplying outlets or devices in most dwelling unit rooms.
• Tamper-Resistant (TR) Receptacles: Required in dwelling units and many other locations to prevent insertion of foreign objects.

## General Equipment Requirements

• Clearances: Sufficient working space must be provided around electrical equipment (e.g., panels, switchboards) for safe operation and maintenance (NEC 110.26).
• Marking: All electrical equipment must be clearly marked with its manufacturer's name, trademark, or other descriptive marking, and its voltage, current, wattage, or other ratings.
• Enclosures: Must be suitable for the environment, specified by NEMA ratings (e.g., NEMA 1 for indoor, NEMA 3R for outdoor rain-tight).

## Motors and Generators: Core Concepts

Motors: Principles and Types

Motors are electromechanical devices that convert electrical energy into mechanical energy, typically rotational motion. Their operation is based on the interaction of magnetic fields. The most common type encountered by electricians is the AC Induction Motor, which uses electromagnetic induction to produce rotation without direct electrical connection to the rotor. Other types include DC Motors (requiring a commutator), Synchronous Motors (running at synchronous speed), and Universal Motors (operating on AC or DC).

Motor Nameplate Data

Understanding a motor's nameplate is crucial. Key information includes:

• Horsepower (HP): Mechanical output rating.
• Full Load Amps (FLA): Current drawn at rated HP and voltage. This is critical for sizing conductors and overloads.
• Voltage: Operating voltage.
• RPM: Revolutions per minute.
• Service Factor (SF): A multiplier that indicates how much overload a motor can safely handle for short periods.
• Code Letter: Indicates the locked-rotor kVA per horsepower, used for sizing branch-circuit short-circuit and ground-fault protection.

Motor Protection and Control (NEC Article 430)

NEC Article 430 is the primary reference for motors. Motors require protection against overload, short-circuit, and ground-faults.

• Overload Protection: Prevents motor damage from sustained overcurrents. This is typically provided by thermal overloads in a motor starter, sized per NEC 430.32. Overload devices must be set at no more than 125% of the motor nameplate FLA for motors with a service factor of 1.15 or greater, or a temperature rise not over 40°C.
• Short-Circuit and Ground-Fault Protection: Protects conductors and motor control equipment from high-magnitude fault currents. This is typically provided by circuit breakers or fuses, sized per NEC 430.52.
• Motor Control: Motor starters (manual or magnetic) are used to start, stop, and protect motors. A disconnecting means (switch or circuit breaker) must be located within sight of the motor and its driven machinery, or be capable of being locked in the open position.

Generators: Basic Principles

Generators perform the opposite function of motors, converting mechanical energy into electrical energy through electromagnetic induction. A conductor moving through a magnetic field, or a changing magnetic field through a conductor, induces an electromotive force (voltage). Generators can produce either AC (alternating current) or DC (direct current) depending on their design (e.g., slip rings for AC, commutators for DC).

## Special Occupancies, Equipment, and Conditions

This section of the Journeyman Electrician Exam covers specific requirements for installations in unique environments or involving specialized equipment, as outlined in the National Electrical Code (NEC) Articles 500-700s and others. Understanding these articles is crucial for safety and compliance.

## Hazardous (Classified) Locations (NEC Articles 500-517)

These locations are categorized by the presence of flammable gases, vapors, liquids, combustible dusts, or ignitable fibers/flyings. Proper wiring methods and equipment are essential to prevent explosions or fires.

• Class I Locations: Flammable gases or vapors are present or may be present in the air in quantities sufficient to produce explosive or ignitable mixtures.
• Group A: Acetylene
• Group B: Hydrogen, butadiene, ethylene oxide, propylene oxide, acrolein
• Group C: Ethylene, cyclopropane, ethyl ether
• Group D: Propane, natural gas, gasoline, hexane, benzene, butane, alcohol, acetone, lacquer solvent, naphtha
• Class II Locations: Combustible dusts are present or may be present.
• Group E: Metal dusts (e.g., magnesium, aluminum)
• Group F: Carbonaceous dusts (e.g., coal, carbon black, coke)
• Group G: Grain dusts, flour, starch, plastic, chemical dusts
• Class III Locations: Ignitable fibers or flyings are present (e.g., textile mills, woodworking).
• Divisions:
• Division 1: Ignitable concentrations are present continuously, intermittently, or periodically under normal operating conditions.
• Division 2: Ignitable concentrations are present only under abnormal conditions (e.g., equipment failure).
• Protection Techniques: Include explosion-proof enclosures, dust-ignition-proof enclosures, intrinsically safe systems, purged and pressurized enclosures, and hermetically sealed devices.
• Sealing: Conduit seals are required where conduits pass from a hazardous to a non-hazardous location or between different hazardous classifications to prevent the passage of gases, vapors, or flames.

## Emergency and Standby Systems (NEC Articles 700, 701, 702)

These systems provide power when the normal supply fails.

• Emergency Systems (Article 700): For life safety and critical loads. Requires immediate and automatic transfer. Examples: egress lighting, fire pumps, elevators.
• Legally Required Standby Systems (Article 701): For loads where interruption could endanger life or health, or hamper rescue or fire-fighting operations. Requires automatic transfer, but a delay is permitted. Examples: communication systems, ventilation.
• Optional Standby Systems (Article 702): For business or property protection. Transfer can be manual or automatic. Examples: data processing, industrial processes.
• Transfer Switches: Must be approved for the purpose and ensure no interconnection between normal and emergency sources.

## Special Equipment and Conditions

• Swimming Pools, Fountains, and Similar Installations (NEC Article 680): Requires extensive GFCI protection for receptacles, lighting, and pool equipment, as well as specific bonding and grounding requirements to minimize shock hazards.
• Solar Photovoltaic (PV) Systems (NEC Article 690): Covers wiring, overcurrent protection, grounding, and disconnects for PV arrays and associated equipment. Includes requirements for rapid shutdown to reduce shock hazards for emergency responders.
• Agricultural Buildings (NEC Article 547): Addresses wiring in corrosive and damp environments, often requiring nonmetallic sheathed cable or nonmetallic conduit.
• Marinas and Boatyards (NEC Article 555): Emphasizes GFCI protection for all receptacles supplying shore power and specific grounding/bonding requirements.

## Health Care Facilities (NEC Article 517)

• Specific requirements for patient care areas, including isolated power systems in critical care (wet procedure) areas, and essential electrical systems for life support and critical operations. Receptacles in patient care areas must be hospital grade.