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Electrical Systems

NEC(R) Overview 231

NEC(R) Overview provides information on the contents, purpose, history, and applications of the National Electrical Code(R). The NEC is the essential standard on minimum safe electrical installations and is intended for use by experienced electrical workers. While the NEC establishes safe practices for working with electrical systems, the Code is not the law unless it is adopted by local government. However, some form of the NEC is adopted as law in all 50 states.

Using and understanding the National Electrical Code is essential for anyone who works with electrical systems. After completing this course, users will be able to navigate the National Electric Code and understand its scope and function.

Difficulty Intermediate
Format Online
Number of Lessons 19
Language English

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The NEC(R)
The History of the Code
The NFPA
NFPA 70E(R) and OSHA
Electrical Standards and Organizations Review
Code Structure
Code Scope
Reading the Code
Code Introduction Review
Code Definitions
Code Measurements
Code Tables
Nationally Recognized Testing Laboratories
Code Details Review
The Code Development Process
Committee Members
Changes to the Code
How the Code Becomes Law
Final Review

Describe the National Electrical Code®.
Describe the history of the Code.
Describe the NFPA.
Describe the relationship between NFPA 70E® and OSHA.
Describe the structure of the Code.
Describe the scope of the Code.
Describe how to read the Code.
Explain how the Code defines terms.
Explain how the Code uses measurements.
Describe the tables in the Code.
Describe nationally recognized testing laboratories.
Describe how the Code is developed.
Identify the classifications for Code committee members.
Describe how changes to the Code are communicated.
Explain how the Code becomes law.

Vocabulary Term

Definition

adoption by reference

A method of entering the NEC into law by creating laws that point to specific sections of the NEC. Adoption by reference is the only method currently supported by the NEC.

adoption by transcription

A method of entering the NEC into law by reproducing the text of the NEC standards as law. Adoption by transcription is no longer supported by the NEC.

American Wire Gauge

AWG. A measurement system that expresses conductor thickness. The American Wire Gauge system assigns whole numbers to conductors that decrease in value as the thickness of conductors increases.

ampacity

The allowable current-carrying capacity of a conductor, measured in amps. Maximum safe ampacities are listed for each wire gauge in NEC tables.

annexes

Sections of a book or document that provide readers with supplemental material. Annexes A-J in the NEC provide readers with additional helpful information that is not part of the official requirements.

Article 100

An article of Chapter 1 that provides definitions of key terms used throughout the NEC. Article 100 consists of three parts that define terms as used in different applications.

Article 110.3

A section of Article 110 that calls for electrical devices and equipment to be labeled and/or listed to certify them as safe for use. The requirements in Article 110.3 are fulfilled by nationally recognized testing laboratories that have completed the OSHA recognition process.

Article 110.6

A section of Article 110 that states that conductor sizes are expressed in American Wire Gauge (AWG) or circular mils. Although Article 110.6 specifies circular mils, most conductor sizes are actually given in thousands of circular mils (kcmils).

Article 80

An article in Annex H that provides a model local ordinance for the administration and enforcement of the NEC. Article 80 is not a requirement but an example to help governments adopt the Code as law.

Article 90.2

A section of Article 90 that states what is and is not covered in the NEC. Article 90.2 also states that special permission may allow the Code to be used for installations that are listed as not covered.

Article 90.5

A section of Article 90 that describes the types of rules and material in the NEC. Article 90.5 explains the difference between mandatory and permissive rules.

Article 90.9

A section of Article 90 that explains the rules for units of measurement in the NEC. Article 90.9 states that the International System of Units (SI) should appear first and inch-pound, or English, units should appear afterwards in parentheses.

Canadian Standards Association

CSA. The major Canadian NRTL. The Canadian Standards Association usually certifies a device based on UL testing.

circular mils

The standard unit of measurement for a wire's cross-sectional area. Circular mils are the square of a conductor's diameter.

Code

The standard for minimum safe electrical installations in the United States. The Code, also referred to as the National Electrical Code or by the technical name NFPA 70, is adopted in some form as law in all 50 states.

conductor

A material that allows the free movement of electrons and electricity. Most conductors are metals.

consumers

A person who purchases products or services that are affected by the NEC. Consumers can provide input about the NEC online.

enforcing authorities

An organization that is in charge of enforcing the NEC. Enforcing authorities may issue citations to facilities that do not comply with NEC standards.

English system

A system of measurement based on the pound, gallon, and inch. The English system, also known as the inch-pound system, is used in only a few English-speaking countries.

General Duty Clause

A statement contained within OSHA's standards that requires employers to offer employment free from health and safety hazards. The General Duty Clause covers situations for which there are no specific standards.

ground fault circuit interrupter

GFCI. A protective device that de-energizes a circuit when a dangerous fault current occurs. Ground fault circuit interrupters should be used whenever there is a chance for electricity to come into contact with water.

hazards

A source of danger or possible injury. Hazards can pose risks to physical well-being or health.

inch-pound system

A system of measurement based on the pound, gallon, and inch. The inch-pound system, also known as the English system, is used in only a few English-speaking countries.

index

An alphabetized list of keywords that provides the locations where different subjects are discussed in a book or document. The index can be more helpful than the table of contents when trying to locate specific information in the NEC.

installers/maintainers

A person responsible for the installation and/or maintenance of electrical products or systems. Installers/maintainers must follow NEC guidelines to keep users safe.

insurance

A representative of the insurance industry. Insurance members work to financially protect facilities when damage from electrical products and systems occurs.

insurers

Members of insurance companies. Insurers work to financially protect facilities when damage from electrical products and systems occurs.

International System of Units

SI. An internationally recognized standard system of measurement based on the gram, liter, and meter. The International System of Units is also known as the metric system.

Intertek Testing Services

The NRTL that uses the ETL listing mark. Intertek Testing Services also uses the CE listing mark internationally.

kcmils

Thousands of circular mils. A unit of measurement for electrical conductors. Kcmils are used to express large conductor sizes.

labor

A person who is involved with increasing and maintaining workplace safety. Labor members are often part of unions or other organizations devoted to improving working conditions.

lockout/tagout

A method of protecting employees from accidental machine startup through proper locking and labeling of machines. Lockout/tagout is an essential practice for safe repair of machines.

mandatory rule

A rule in the NEC that must always be followed. A mandatory rule uses the words "shall" or "shall not."

manufacturers

An organization that makes an electrical product or system. Manufacturers often provide guides to help use their products.

Maryland Electrical Testing Laboratories

MET. The first NRTL listing organization to pass the OSHA recognition process. Maryland Electrical Testing Laboratories markings are accepted everywhere in the United States.

metric system

An internationally recognized standard system of measurement based on the gram, liter, and meter. The metric system is also known as the International System of Units (SI).

National Electrical Code

NEC. The standard for minimum safe electrical installations in the United States. The National Electrical Code, also referred to as the Code or by the technical name NFPA 70, is adopted in some form as law in all 50 states.

National Fire Protection Association

NFPA. A non-profit organization that maintains standards of public safety and fire prevention. The National Fire Protection Association was originally formed to develop standards for sprinkler systems.

nationally recognized testing laboratory

NRTL. An organization that certifies the safety of devices through listing and labeling. Nationally recognized testing laboratories must pass the OSHA recognition process before they can certify devices.

NEC

National Electrical Code. The standard for minimum safe electrical installations in the United States. The NEC, also referred to as the Code or by the technical name NFPA 70, is adopted in some form as law in all 50 states.

NFPA

National Fire Protection Association. A non-profit organization that maintains standards of public safety and fire prevention. The NFPA was originally formed to develop standards for sprinkler systems.

NFPA 70

The standard for minimum safe electrical installations in the United States. NFPA 70, also referred to as the National Electrical Code or the Code, is adopted in some form as law in all 50 states.

NFPA 70E

The standard for electrical safety in the workplace. NFPA 70E is a corollary to the NEC that OSHA uses to establish electrical work safety guidelines.

Occupational Safety and Health Administration

OSHA. A government agency that sets the standards for working conditions in the United States. The Occupational Safety and Health Administration ensures that employees work in safe and healthy environments.

optical cables

A conductor that contains fibers that carry light. Optical cables do not carry electricity, but they are covered by the NEC because they depend on electrical systems to function.

OSHA

Occupational Safety and Health Administration. A government agency that sets the standards for working conditions in the United States. OSHA ensures that employees work in safe and healthy environments.

OSHA recognition process

A thorough, formal process used to certify listing organizations as qualified to deem devices safe for use. The OSHA recognition process enables organizations to ensure that electrical products provide protection against known safety risks.

OSHA standards

An OSHA policy on a particular practice or method. OSHA standards have the same power as law, and non-compliance can result in fines or other penalties.

permissive rule

A rule in the NEC that is acceptable but not necessary. A permissive rule uses the words "shall be permitted" or "shall not be required."

research/testing

A representative of an independent lab that tests electrical products and systems. Research/testing members help develop the Code to include advancements in and new types of electrical equipment and systems.

special experts

A person with expertise in a specific area of the NEC. Special experts ensure that the different areas of the NEC contain accurate, updated information.

table of contents

A sequentially ordered list of topics found in the front of a book or document. The table of contents shows where the chapters and articles can be found in the NEC.

trade size

An industry-standard approximation for a given size. A trade size of 1/2 in. may have an actual measurement of up to 0.7 in. depending on the situation.

Underwriters Laboratories

UL. One of the most recognized NRTLs dedicated to product safety testing and certification. Underwriters Laboratories wrote many standards for safe devices before OSHA formalized the process.

union

A group that workers form in order to protect their positions and rights in the workplace. In the electrical industry, unions often strive to increase worker safety.

users

Any person who uses the NEC on a regular basis. Users may need guidelines or other assistance to use the NEC effectively.

utility company

An entity recognized by governmental law that installs, operates, and maintains electric supply. Most utility company installations are not covered under the scope of the NEC.

volts

V. A unit of measurement that indicates the amount of electrical force or pressure in a circuit. Volts measure voltage, which is also known as electromotive force.

wire gauge

A standard of measurement used to determine the diameter of a wire conductor. Wire gauge numbers increase as wire diameters get smaller.