General Requirements & Code Administration

Chapter 1: General Requirements & Code Administration

Learning Objectives

Upon completing this chapter, you will be able to:

1.1 The Purpose and Scope of the NEC (Article 90)

The National Electrical Code (NEC) is not a design specification; it is a safety standard. Its primary purpose is the practical safeguarding of persons and property from hazards arising from the use of electricity. The Code is not intended as an instruction manual for untrained individuals, nor is it intended to be a design guide for efficient or convenient electrical systems.

Key Concepts:

Exam Trap: Questions often ask about the purpose of the Code. The answer is always about safety, not about convenience, efficiency, or providing a design guide.

1.2 Code Structure and Mandatory vs. Permissive Rules

The NEC is organized into an Introduction (Article 90) and nine Chapters. Chapters 1–4 apply generally to all installations, while Chapters 5–7 apply to special occupancies, special equipment, and special conditions. Chapter 8 (Communications) is independent of the other chapters unless specifically referenced.

Mandatory Rules use the word "shall." This is a requirement that must be followed.

Permissive Rules use the word "shall be permitted." This is an allowance or an option that is acceptable but not required.

Explanatory Material is in the form of Fine Print Notes (FPNs). These are not mandatory; they are informational only. They often explain the reason behind a rule or provide guidance on how to comply.

Code Navigation:

Exam Trap: A question may state, "Per the NEC, it is permitted to..." This is a permissive rule. A question stating, "The NEC requires..." is a mandatory rule. Do not confuse the two.

1.3 General Installation Requirements (Article 110)

Article 110 is the foundation for all electrical installations. It covers the requirements for conductors, equipment, and the means of installation.

1.3.1 Conductor Identification (110.12)

Field Point: When pulling wire, always verify the neutral is white/gray and the ground is green/bare. Using white tape to re-identify a black conductor as a neutral is only permitted for specific applications (e.g., cable assemblies) and must be done at the terminations.

1.3.2 Available Fault Current (110.9, 110.10)

All equipment intended to interrupt current at fault levels must have an interrupting rating sufficient for the available fault current at its line terminals. Equipment must also be able to withstand the thermal and mechanical stresses of a fault.

Field Point: When replacing a panelboard, you must verify the available fault current on the label matches the new equipment's rating. This is a common inspection failure.

1.3.3 Mounting and Clearances (110.13, 110.26)

Exam Trap: The 36-inch depth is a minimum for equipment operating at 0–150 volts to ground with exposed live parts on one side and grounded parts on the other. If live parts are on both sides, the depth increases to 42 inches.

1.4 Voltage Drop (210.19, 215.2)

The NEC does not mandate a specific voltage drop for branch circuits or feeders as a hard rule, but it is a recommendation in the FPNs. The recommended maximum is 3% for a branch circuit and 5% total for feeders and branch circuits combined.

Calculation (Simplified):

Voltage Drop (VD) = (2 × Length (L) × Current (I) × Resistance (R)) / 1000

For single-phase circuits. For three-phase, the multiplier is √3 (1.732) instead of 2.

Field Point: For long runs, you must upsize conductors to compensate for voltage drop. Remember that when you upsize conductors for voltage drop, you must also upsize the equipment grounding conductor proportionally (per 250.122(B)).

Exam Trap: The NEC recommends voltage drop, but it does not require it. A question asking for the "maximum allowable voltage drop per the NEC" is a trap. The correct answer is that it is a recommendation, not a mandatory requirement.

1.5 Conductor Ampacity and Overcurrent Protection (Articles 240, 310)

1.5.1 Ampacity Tables

Conductor ampacity is determined from the tables in Article 310. The most common table is Table 310.16 (formerly 310.15(B)(16)), which provides ampacities for conductors rated 0–2000 volts, based on insulation type and ambient temperature of 30°C (86°F).

Key Columns:

Exam Trap: The ampacity of a conductor is limited by the lowest temperature rating of any termination, connection, or device in the circuit. You cannot use the 90°C column for the final ampacity unless the terminations are rated for 90°C. In most cases, you will use the 75°C column for terminations.

1.5.2 Overcurrent Protection (Article 240)

Overcurrent devices (fuses and circuit breakers) must protect conductors against overcurrent. The general rule is that the overcurrent device rating must not exceed the conductor's ampacity.

Standard Ratings (240.6): 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 125, 150, 175, 200, 225, 250, 300, 350, 400, 450, 500, 600, 700, 800, 1000, 1200, 1600, 2000, 2500, 3000, 4000, 5000, 6000.

Next Size Up Rule (240.4(B)): If the conductor ampacity does not correspond to a standard overcurrent device rating, you are permitted to use the next higher standard rating, provided:

Exam Trap: This rule applies to standard sizes. You cannot use it to protect a 14 AWG conductor (15A ampacity) with a 20A breaker if the load is 16A. The conductor ampacity must be at least equal to the load.

1.5.3 Derating (310.15)

When more than three current-carrying conductors are in a raceway or cable, the ampacity must be derated using the adjustment factors in Table 310.15(B)(3)(a) . For example, 4–6 conductors require an 80% adjustment factor.

Field Point: Neutrals are not counted as current-carrying conductors if they only carry the unbalanced current of a multi-wire branch circuit (shared neutral). However, neutrals in a single-phase 120/240V circuit are counted if they are part of a 2-wire circuit.

1.6 Services, Feeders, and Branch Circuits (Articles 210, 215, 230)

1.6.1 Branch Circuits (Article 210)

A branch circuit is the portion of the wiring system between the final overcurrent device and the outlets.

Multi-wire Branch Circuits (210.4): A multi-wire branch circuit consists of two or more ungrounded conductors (hots) that share a common grounded conductor (neutral). They must be provided with a means to simultaneously disconnect all ungrounded conductors.

Field Point: In a commercial kitchen, you might run a 3-phase, 4-wire multi-wire branch circuit to feed several 120V receptacles. The neutral is shared, but the breakers must be tied together (handle ties) to ensure all hots are disconnected simultaneously.

1.6.2 Feeders (Article 215)

Feeders are the conductors between the service equipment and the branch circuit overcurrent devices.

1.6.3 Services (Article 230)

The service is the conductors and equipment that deliver electricity from the utility to the service disconnecting means.

Service Disconnect (230.70, 230.71): Each service must have a disconnecting means that is readily accessible. The disconnect must be located at a readily accessible point nearest to the point of entrance of the service conductors.

Exam Trap: The service disconnect must be installed before the conductors enter the building, or immediately inside the point of entrance. You cannot run service conductors through a building to a disconnect in the back.

1.7 Grounding and Bonding (Article 250)

This is the most critical and complex article in the Code. The key difference:

Purpose: Grounding limits voltage surges and stabilizes voltage. Bonding ensures that fault current has a low-impedance path back to the source, which allows overcurrent devices to operate quickly.

Key Components:

Exam Trap: The neutral is only bonded to the grounding system at the first disconnecting means (the main service panel). In a sub-panel, the neutral must be isolated from the enclosure and the equipment grounding conductors.

1.8 Code Navigation: Quick Reference Table

1.9 Common Exam Traps and Field Pitfalls

1.10 Practical Field Application

As a journeyman, your daily work is governed by these general requirements. Before you pull a single wire, you should:

Mastering these foundational rules is the key to passing the Texas Journeyman exam. The questions will test your ability to apply these concepts to real-world scenarios, so always think about what you would do on a job site, and then find the specific code rule that supports that action.