NEC Overview 150

This class introduces the NEC codebook and explains how it is used by electrical workers. Includes an Interactive Lab.


Class Name:
NEC Overview 150
This class introduces the NEC codebook and explains how it is used by electrical workers. Includes an Interactive Lab.
Number of Lessons:
Additional Language:

Class Outline

  • Objectives
  • What Is the NEC?
  • NEC History
  • The NFPA
  • How the Code Is Developed
  • Changes to the Code
  • Code Scope
  • Code Structure
  • Code Definitions
  • How Code Becomes Law
  • How to Read the Code
  • Code Tables
  • Code Abbreviations
  • Code Measurements
  • NFPA 70E and OSHA
  • Nationally Recognized Testing Laboratories
  • Summary


  • Describe the NEC.
  • Describe the history of the NEC.
  • Describe the NFPA.
  • Describe how the NEC is developed.
  • Describe how changes to the code are communicated.
  • Describe the scope of the NEC.
  • Describe how the NEC is structured.
  • Explain how the NEC defines terms.
  • Explain how the NEC becomes law.
  • Describe ways to read the NEC.
  • Describe NEC tables.
  • Explain how the NEC uses abbreviations.
  • Explain how the NEC uses measurements.
  • Describe the relationship between NFPA 70E and OSHA.
  • Describe Nationally Recognized Testing Laboratories.


  • MSSC Maintenance Awareness


Vocabulary Term Definition
.2 The section number of articles of the NEC in which definitions appear. Not all articles have specific definitions.
AC Armored Cable. Type AC is a fabricated assembly of insulated conductors in a flexible metallic enclosure.
accessible A term the NEC defines for wiring methods as "capable of being removed or exposed without damaging the building structure or finish or not permanently closed in the structure or finish of the building."
adoption by reference Method of entering the NEC into law by creating laws that point to specific sections of the NEC.
adoption by transcription Method of entering the NEC into law by reproducing the NEC standards as law.
AFCI Abbreviation for arc-fault circuit interrupter. An AFCI is a device that deenergizes a circuit when an arc fault is detected.
annex A section of a book that provides supplimental material. The NEC has annexes A-G with additional helpful information.
Article 100 The first article of Chapter 1 of the NEC. Article 100 provides the NEC's definitions of the key terms used throughout the text.
Article 110 The article that covers general requirements for the examination and approval, installation, and use of electrical conductors and equipment.
Article 110.3 Section covering "Examination, Identification, Installation, and Use of Equipment." 110.3(B) calls for equipment to be listed or labeled.
Article 80 A model local ordinance for the administration and enforcement of the NEC. Article 80 was moved from the beginning to Annex G in the 2005 NEC.
Article 90 The introductory article of the NEC. Article 90 lays the groundwork for the writing and application of the NEC.
Article 90.2 Section of Article 90, titled "Scope," that states what the NEC will and will not cover.
Article 90.3 Section of Article 90, titled "Code Arrangement," that states how the NEC is structured.
Article 90.5 Section of Article 90 that explains mandatory and permissive rules.
Article 90.9 Section of Article 90 that explains NEC rules for units of measurement.
AWG American Wire Gage. AWG are units used to express conductor sizes, required in Article 110.6.
Canadian Standards Association The major Canadian listing agency. CSA usually certifies a device based on UL testing.
Chapter 9 The final chapter of the NEC, containing tables.
Code A standard that is an extensive compilation of provisions covering broad subject matter or that is suitable for adoption into law independently of other codes and standards. Also, when capitalized, used to stand for the NEC.
Code-Making Panel One of 19 groups responsible for producing sections of the NEC. Code making panels consist of elected volunteers from a variety of electrical backgrounds.
cross reference A reference from one part of a book to another part containing related material. NEC articles and the index are cross referenced.
English system The system of units used in the United States based on the inch, the pound, and Fahrenheit degrees.
ENT Electrical Non-metallic Tubing. ENT is used in raceways.
FPN Abbreviation for the fine-print notes that supplement the article rules. FPNs are not requirements and are for information purposes only.
General Duty Clause OSHA's main standard that requires "a place of employment free from recognized hazards that are causing or likely to cause death or serious physical harm."
GFCI Ground-fault circuit interrupter. A GFCI is a device that deenergizes a circuit when a dangerous current fault occurs.
inch-pound Another name for the English system of measurement. The United States is one of the few countries still using the inch-pound system.
index An alphabetized list of subjects discussed in a book, giving the page or pages on which each item is mentioned.
Intertek Testing Services The NRTL that uses the ETL and CE listing marks.
kcmil Abbreviation for circular mils. Kcmil is a unit used to express conductor size.
labeled Marked with an Indication that a device has been tested and deemed fit for a specific purpose by a listing agency, with the appropriate label applied to the device.
listed Indicated that a device has met the testing and other requirements set by a listing agency. NRTLs are listing agencies.
lockout/tagout A method of protecting employees from accidental machine startup through proper locking and labeling of machines that are undergoing maintenance.
mandatory rule A provision of the NEC that must be followed by law. Mandatory rules are marked by the word "shall."
MET Laboratories The first listing organization to pass the OSHA NRTL process.
metric system The international system of units based on the meter, kilogram, and Celsius degrees. The NEC uses the metric system to be universal.
National Electrical Code The standard for minimum safe electrical installations. The NEC is adopted in some form as law in all 50 states.
National Fire Protection Association The organization that produces the National Electric Code. The NFPA is primarily a volunteer organization.
Nationally Recognized Testing Laboratory A listing organization that has passed the OSHA Recognition Process. NRTLs certify the safety of devices through listing and labeling.
NFPA 70 The National Fire Protection Association's technical name for the National Electric Code.
NFPA 70E A corollary to the NEC known as Standard for Electrical Safety in the Workplace. NFPA 70E is used by OSHA for work safety guidelines.
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 to certify listing organizations as qualified to deem devices safe for use.
permissive rule A provision of the NEC that is suggested as one of several alternatives to meet the requirements of law. Permissive rules are marked by the words "shall be permitted."
raceway An enclosed channel of metal or nonmetallic materials designed expressly for holding wires or cables.
scope The range of subjects or topics covered by a given subject. The NEC in general and each article clearly state the range of material they will cover.
SI Abbreviation for metric system.
Table 310.16 Frequently used NEC table to find "Allowable Ampacities of Insulated Conductors."
table of contents A sequentially ordered list found in the front of a book that shows where general topics can be found.
tables A set of data arranged in rows and columns. Tables allow for the easy comparison of data.
trade size A term used to distinguish between actual sizes and industry standard approximation for that size. A trade size of ½ in. may reflect an actual size of up to .7 in.
Underwriters Laboratories Perhaps the most recognizable NRTL. UL wrote many of the standards for safe devices before OSHA formalized the process.
utility company An entity recognized by governmental law that installs, operates, and maintains electric supply. Most utility installations are not covered under the scope of the NEC.
wire gage The cross-section diameter of a wire, or simply, its thickness. The NEC expresses wire gage in AWG or kcmil units.