An introduction to the National Electrical Code

If you spend any time around Electricians you will hear a lot of discussion about “The Code”

As Electricians, during the course of our work we are governed by the rules and regulations of the National Electrical Code and so it is vital that we have a working knowledge of it.

So why is it important for us to know about the NEC?

In order for us to understand this, we need to take a brief look back at the history of Electricity in America.

The first controlled use of electricity occurred in the mid 1800’s with the invention of electric generators and later on towards the end of the century inventors like Nikola Tesla and Thomas Edison developed systems for the distribution of electrical power.

The electric light was perfected for practical use in the 1880’s and from then on electricity began to make its way into more and more widespread use.

As electricity began to become commonplace and make its way into more and more places it became obvious that there needed to be some standardization of installation procedures due to the large number of electrical fires and electrical hazards being created and so the first National Electrical Code was published in 1897 by the National Fire Prevention Association and it has grown from a small booklet of 60 pages to today’s book of almost 1000 pages.

What is the National Electrical Code

The National Electrical Code is a national standard for the United States for the safe installation of Electrical infrastructure to include wiring and equipment. The NEC is not a federal law but it is commonly mandated by State and Local laws throughout the United States.

As Electricians, all aspects of our work are governed by strict adherence to the rules of the Electrical Code and Regional and Local State Code requirements.

If we don't follow the electrical code we don't pass inspection, and if we don't pass inspection we don't get paid for our work, so as Electricians we are incentivized to learn and practice the National Electrical Code.

The professional Electrician needs to consult at all times that he is following the correct guidelines in all practices and installations. It is not expected for the Electrician to internalize or memorize the entire codebook but it is generally accepted that interested persons will familiarize themselves with aspects of the code in common use during everyday Electrical work.

As a general rule we should be familiar with the basics of the main articles of code that we come across every day, for example we should all know the correct spacing and recommended heights for electrical outlets and switches

As stated earlier the NEC codebook is approximately 1000 pages so what is required from electricians is to know how to reference the codebook and to know where to find the information that you will need. It will be of great help to know something about the layout and structure of the Codebook in order to better understand where to look for the information when we need it.

The NEC Codebook comprises an introduction, nine chapters, annexes A through J and the index at the rear of the book.

Article 90: Introduction.

Purpose: To establish the practical safeguarding of people and property from electrical hazards.

Scope: It describes what installations are covered by the NEC including public and private premises.

Code Arrangement: Explains the structure and organization of the NEC

Enforcement: States that the authority having jurisdiction (AJH) is responsible for enforcing the code.

Explainations: Provides guidance on how to interpret the NEC requirements.

Chapter 1 - General rules.

Chapter 1 of the National Electrical Code explains the General Requirements for electrical installations.

Chapter 1 is divided into two topics.

Article 100 - Definitions

The purpose of Article 1 is to define and explain the terms and language used throughout the Codebook to ensure consistency of practice and clarity of understanding.

Article 110 - Requirements for Electrical Installations.

The purpose of Chapter 1 is to establish the general requirements, principles and practices that must be followed to ensure safe and Code compliant electrical installations.

It requires that electrical equipment be approved and suitable for their intended use.

It also provides direction as to clearances and access requirements around electrical equipment to ensure safe operation and maintenance of all equipment.

In addition it specifies requirements for proper mounting and cooling of electrical equipment to ensure safe and proper operation.

Chapter 1 establishes general requirements and definitions that ensure safe and reliable operation of electrical equipment and consistent understanding across a variety of applications.

Chapter 2 - Wiring and Protection

Chapter 2 of the NEC is dedicated to outlining the specific requirements for wiring and protection. It provides detailed rules to ensure the safe installation and protection of electrical wiring systems and the protective measures required to ensure safety and functionality.

These are the main articles and their focus.

• Article 200: Use and identification of grounded conductors

• Article 210: Branch Circuits

• Article 215: Feeders

• Article 220: Branch Circuit, Feeder, and Service Load Calculations

• Article 225: Outside Branch Circuits and Feeders

• Article 230: Services

• Article 240: Overcurrent Protection

• Article 250: Grounding and Bonding

Chapter 3 - Wiring Methods and Materials

Chapter 3 of the National

Electrical Code (NEC) covers "Wiring Methods and Materials."

This chapter provides guidelines and requirements for the installation of electrical wiring systems, including the types of wiring methods, materials allowed, and installation practices to ensure safety and compliance.

The topics addressed in this chapter include:

• General requirements for wiring methods and materials

• Use and identification of conductors

• Conduits, cables, and raceways

• Boxes and fittings

• Flexible cords and cables

• Installation practices for different types of wiring systems

Chapter 4 - Equipment for General Use

Chapter 4 of the National Electrical Code (NEC) addresses "Equipment for General Use."

This chapter provides regulations for the installation, use, and maintenance of electrical equipment to ensure its safe and proper operation.

Key topics typically covered in Chapter 4 include:

• Switches

• Receptacles and outlets

• Lighting fixtures, lampholders, and lamps

• Appliances

• Motors, motor circuits, and controllers

• Transformers and transformer vaults

• Capacitors

• Generators

• Storage batteries

• Photovoltaic systems

Chapter 5 - Special Occupancies

This chapter provides specific requirements and regulations for electrical installations in locations that are considered hazardous or unique.

The main articles in chapter 5 are,

• Article 500-506 Hazardous Locations, Aircraft hangars, Bulk Storage Plants & Fuel Dispensing Facilities.

• Article 510-516 Specific Occupancies and Equipment

• Article 517: Health Care Faclities, Hospitals, Clinics and Nursing Homes,

• Article 518: Assembly Occupancies, Theaters, Auditoriums and Sports Arenas.

• Article 520: Theaters, Audience areas of Motion Picture and Television Studios, Performance Areas and Similar Locations.

• Article 525: Carnivals, Circuses, Fairs, and Similar Events

• Article 530: Motion Picture and Television Studios and Similar Locations.

• Article 545: Manufactured Building and Relocatable Structures.

• Article 547: Agricultural Buildings

• Article 550: Mobile Homes, Manufactured Homes, and Mobile Home Parks.

• Article 550: Marinas, Boatyards, and Docking Facilities.

• Article 590: Temporary Installations.

Chapter 6 - Special Equipment

This Chapter addresses the specific requirements that do not fall under the general rules of Chapters 1 through 4.

The main articles are,

• Article 600: Electric Signs and Outline Lighting

• Article 604: Manufactured Wiring Systems

• Article 610: Cranes and Hoists

• Article 620 Elevators, Dumbwaiters, Escalators, Moving Walkways, Platform Lifts and Stairway Lifts,

• Article 625: Electric Vehicle Power Transfer Systems

• Article 630: Electric Welders

• Article 640: Audio Signal Processing, Amplification, and Reproduction Equipment.

• Article 645: Information Technology Equipment

• Article 660: X-Ray Equipment

• Article 670: Industrial Machinery

• Article 680: Swimming Pools

• Article 690: Solar Photovoltaic Systems

• Article 645: Fire Pumps
  

Chapter 7 - Special Conditions

This chapter includes specific requirements and provisions for electrical systems and equipment used in unusual or demanding conditions such as emergencies, hazardous locations, and special-purpose systems.

The main articles in Chapter 7 are,

• Article 700: Emergency Systems

• Article 701: Legally Required Standby Systems

• Article 705: Interconnected Electric Power Production Sources

• Article 706: Energy Storage Systems

• Article 708: Critical Operations Power Systems

• Article 710: Stand-Alone Systems, off grid solar PV systems

• Article 720: Circuits and Equipment Operating at less than 50 Volts

• Article 728: Fire-Resistive Cable Systems

• Article 750: Energy Management Systems

Chapter 8 - Communication Systems.

This chapter deals with the requirements for the intallation and maintenance of communication systems including telephone, radio, television and broadband.

The main articles in Chapter 8 are,

• Article 800: General Requirements for Communication Systems.

• Article 805: Communications Circuits

• Article 810: Radio and Television Equipment

• Article 820: Community Antenna Television and Radio Distribution Systems

• Article 830: Network Powered Broadband Communications Systems

• Article 840: Premises Powered Broadband Communications Systems

Chapter 9 - Tables

Chapter 9 provides various tables that are essential for the proper design and installation of electrical systems. These tables provide necessary information calculating conduit fill, conductor ampacities, voltage drops and other very important factors.

The main components of Chapter 9 are,

Table 1: Percentage of Cross-section section of Conduit and Tubing for Conductors.

Table 2: Radius of Conduit and Tubing Bends

Table 3: Dimensions of Conduits and Tubings

Table 4: Dimension of Rigid Metal Conduit. (RMC)

Table 5: Dimensions of Intermediate Metal Conduit

Table 5A: Dimensions of Aluminum Rigid Metal Conduit

Table 6: Dimensions of Electrical Metallic Tubing (EMT)

Table 7: Dimensions of Flexible Metal Conduit (FMC)

Table 8: Conductor Properties

Table 9: Alternating-Current Resistance and Reactance for 600-Volt Cables