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47-548: The "authority having jurisdiction" inspects for compliance with the standards. The NEC should not be confused with the National Electrical Safety Code (NESC), published by the Institute of Electrical and Electronics Engineers (IEEE). The NESC is used for electric power and communication utility systems including overhead lines, underground lines, and power substations. The NEC is developed by NFPA's Committee on

94-912: A Label Service for certain product categories that require more frequent inspections. Products that passed UL's testing and regular inspections were given a UL label, which eventually evolved into the UL Mark. From 1905 to 1979, UL Headquarters was located at 207-231 East Ohio Street in Chicago. In 1979, the organization moved its headquarters to a 153-acre campus in Northbrook, Illinois, 25 miles north of its former downtown Chicago location. UL Solutions has evolved from its roots in electrical and fire safety to address broader safety issues, such as hazardous substances, water quality, food safety, performance testing, safety and compliance education, and environmental sustainability . On January 1, 2012, Underwriters Laboratories became

141-600: A change in between code editions are handled through a Tentative Interim Amendment (TIA) process. Original work on the NESC began in 1913. The NESC is structured into parts, sections, and rules. There are general sections at the beginning of the book covering the introduction, definitions, references, and grounding. Following the general section are four main parts including: substations rules (Part 1), overhead line rules (Part 2), underground line rules (Part 3), and work rules (Part 4). Underwriters Laboratories The UL enterprise

188-505: A given type of room, based upon the typical cord length of small appliances. As of 1962, the NEC required that new 120 Volt household receptacle outlets, for general purpose use, be both grounded and polarized . NEMA connectors implement these requirements. The NEC also permits grounding-type receptacles in non-grounded wiring protected by a GFCI; this only applies when old non-grounded receptacles are replaced with grounded receptacles, and

235-424: A greater heat dissipation rating than standard three-wire NM-2 cable , which includes two tightly bundled load and return wires. NEC, like many NFPA standards, relies on sales of its copyrighted standards to fund its development. In 2016, the group PUBLIC.RESOURCE.ORG, INC published copies of the code online free of cost, arguing that as a standard adopted as law, it should be publicly available. The case challenges

282-641: A growing potential in this field, Merrill stayed in Chicago to found Underwriters Laboratories. He received initial funding from the Chicago Fire Underwriters' Association and the Western Insurance Union, a local insurance organization. With $ 350 of equipment, he opened a small laboratory on the third floor of a local fire insurance patrol station, signing UL's first test report on March 24, 1894. Merrill soon went to work on developing safety standards, conducting tests, and uncovering hazards. In

329-542: A list of approved testing laboratories, which are known as Nationally Recognized Testing Laboratories . According to Lifehacker , UL Solutions is the best-known product safety and certification organization globally. Underwriters Laboratories Inc. was founded in 1894 by William Henry Merrill . After graduating from the Massachusetts Institute of Technology (MIT) with a degree in electrical engineering in 1889, Merrill went to work as an electrical inspector for

376-475: A new coding model and it is not yet accepted by any jurisdiction as law, it is still the private property of the standards organization and the reader may be restricted from downloading or printing the text for offline viewing. For that privilege, the coding model must still be purchased as either printed media or electronic format (e.g. PDF .) Once the coding model has been accepted as law, it loses copyright protection and may be freely obtained at no cost. The NEC

423-414: A system whereby a city can best avoid lawsuits by adopting a single standard set of building code laws. This has led to the NEC becoming the de facto standard set of electrical requirements. A licensed electrician will have spent years of apprenticeship studying and practicing the NEC requirements prior to obtaining their license. The Deactivation and Decommissioning (D&D) customized extension of

470-407: Is a United States standard of the safe installation, operation, and maintenance of electric power and communication utility systems including power substations, power and communication overhead lines, and power and communication underground lines. It is published by the Institute of Electrical and Electronics Engineers (IEEE). "National Electrical Safety Code" and "NESC" are registered trademarks of

517-671: Is a global private safety company headquartered in Northbrook, Illinois , composed of three organizations, UL Research Institutes , UL Standards & Engagement and UL Solutions . Established in 1894, the UL enterprise was founded as the Underwriters' Electrical Bureau (a bureau of the National Board of Fire Underwriters ), and was known throughout the 20th century as Underwriters Laboratories . On January 1, 2012, Underwriters Laboratories became

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564-692: Is composed of an introduction, nine chapters, annexes A through J, and the index. The introduction sets forth the purpose, scope, enforcement, and rules or information that are general in nature. The first four chapters cover definitions and rules for installations (voltages, connections, markings, etc.), circuits and circuit protection, methods and materials for wiring (wiring devices, conductors, cables, etc.), and general-purpose equipment (cords, receptacles, switches, heaters, etc.). The next three chapters deal with special occupancies (high risk to multiple persons), special equipment (signs, machinery, etc.) and special conditions (emergency systems, alarms, etc.). Chapter 8

611-446: Is not readily available and is not manufactured below size #8 AWG. Hence, copper wire is used almost exclusively in branch circuitry. A ground fault circuit interrupter (GFCI) is required for all receptacles in wet locations defined in the Code. The NEC also has rules about how many circuits and receptacles should be placed in a given residential dwelling, and how far apart they can be in

658-455: Is numbered based on the chapter it is in. Those wiring methods acceptable by the NEC are found in chapter 3, thus all approved wiring method code articles are in the 300s. Efforts have been underway for some time to make the code easier to use. Some of those efforts include using the same extension for both code articles and for the support of wiring methods. The NFPA also publishes a 1,497-page NEC Handbook (for each new NEC edition) that contains

705-440: Is specific to additional requirements for communications systems (telephone, radio/TV, etc.) and chapter 9 is composed of tables regarding conductor, cable and conduit properties, among other things. Annexes A-J relate to referenced standards, calculations, examples, additional tables for proper implementation of various code articles (for example, how many wires fit in a conduit) and a model adoption ordinance. The introduction and

752-460: The fill rating . If the accepted fill rating is exceeded, then all the cables in the conduit are derated , lowering their acceptable maximum ambient operating temperature . Derating is necessary because multiple conductors carrying full-load power generate heat that may exceed the normal insulation temperature rating. (NEC 310.16) The NEC also specifies adjustments of the ampacity for wires in circular raceways exposed to sunlight on rooftops, due to

799-406: The 1999 code is the arc-fault circuit interrupter (AFCI). This device detects arcs from hot to neutral that can develop when insulation between wires becomes frayed or damaged. While arcs from hot to neutral would not trip a GFCI device since current is still balanced, circuitry in an AFCI device detects those arcs and will shut down a circuit. AFCI devices generally replace the circuit breaker in

846-412: The 2023 edition being the most current. Most states adopt the most recent edition within a few of years of its publication. As with any "uniform" code, jurisdictions may regularly omit or modify some sections, or add their own requirements (sometimes based upon earlier versions of the NEC, or locally accepted practices). However, no court has faulted anyone for using the latest version of the NEC, even when

893-642: The Boston Board of Fire Underwriters. At the turn of the twentieth century, fire loss was on the rise in the United States, and the increasing use of electricity in homes and businesses posed a serious threat to property and human life. In order to determine and mitigate risk, Merrill proposed to open a laboratory where he would use scientific principles to test products for fire and electrical safety. The Boston Board of Fire Underwriters turned this idea down, perhaps due to Merrill's youth and relative inexperience at

940-601: The IEEE. The NESC should not be confused with the National Electrical Code (NEC), which is published by the National Fire Protection Association (NFPA) and intended to be used for residential, commercial, and industrial building wiring. The NESC is written as a voluntary standard. It is typically adopted as law by individual states or other governmental authorities. To determine the legal status of

987-491: The NESC, the state public service commission, public utility commission, or other governmental authority should be contacted. Most U.S. states adopt the NESC in some form or fashion. The state of California is an exception and writes its own utility codes, titled General Order 95 (GO95) for overhead lines and General Order 128 (GO128) for underground lines. The NESC is written by various sub committees. The organizations represented, subcommittees, and committee members are listed in

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1034-647: The National Electrical Code, which consists of twenty code-making panels and a technical correlating committee. Work on the NEC is sponsored by the National Fire Protection Association. The NEC is approved as an American national standard by the American National Standards Institute (ANSI). It is formally identified as ANSI/NFPA 70. First published in 1897, the NEC is updated and published every three years, with

1081-473: The aluminum wire used was manufactured to conform to the 1350 series aluminum alloy, but this alloy was eventually deemed unsuitable for branch circuits due to galvanic corrosion where the copper and aluminum touched, resulting in poor contact and resistance to current flow, connector overheating problems, and potential fire risk. Today, a new aluminum wire (AA-8000) has been approved for branch circuits that does not cause corrosion where it contacts copper, but it

1128-511: The authority having jurisdiction. The temperature rating of a wire or cable is generally the maximum safe ambient temperature that the wire can carry full-load power without the cable insulation melting, oxidizing, or self-igniting. A full-load wire does heat up slightly due to the metallic resistance of the wire, but this wire heating is factored into the cable's temperature rating. (NEC 310.10) The NEC specifies acceptable numbers of conductors in crowded areas such as inside conduit, referred to as

1175-559: The authority to deny approval for even listed and labeled products. Likewise, an AHJ may make a written approval of an installation or product that does not meet either NEC or listing requirements, although this is normally done only after an appropriate review of the specific conditions of a particular case or location. Article 210 addresses "branch circuits" (as opposed to service or feeder circuits) and receptacles and fixtures on branch circuits.Electrical Construction and Maintenance Magazine, Branch Circuits, Part 2. There are requirements for

1222-405: The circuit. As of the 1999 National Electrical Code, AFCI protection is required in new construction on all 15- and 20-amp, 125-volt circuits to bedrooms. The NEC requires that conductors of a circuit must be inside a raceway, cable, trench, cord, or cable tray. Additional protection such as NM cable inside raceway is needed if the installation method is subjected to physical damage as determined by

1269-530: The company at about $ 7   billion. The company is listed on the New York Stock Exchange . The Recognized Component Mark is a type of safety certification mark issued by UL Solutions. It is placed on components which are intended to be part of a UL certified end product, but which cannot bear the full UL mark themselves. The general public does not ordinarily come across it, as it is borne on components which make up finished products. UL offers

1316-525: The current exceeds a fixed value for a fixed time, a GFCI device will interrupt electrical service when more than 4 to 6 milliamperes of current in either conductor leaks to ground. A GFCI detects an imbalance between the current in the "hot" side and the current in the "neutral" side. One GFCI receptacle can serve as protection for several downstream conventional receptacles. GFCI devices come in many configurations including circuit-breakers, portable devices and receptacles. Another safety device introduced with

1363-487: The device. A fee is paid to the listing agency for each item so labeled, that is, for each label. Most NRTLs will also require that the manufacturer's facilities and processes be inspected as evidence that a product will be manufactured reliably and with the same qualities as the sample or samples submitted for evaluation. An NRTL may also conduct periodic sample testing of off-the-shelf products to confirm that safety design criteria are being upheld during production. Because of

1410-595: The early years, UL tested three main types of products: devices meant to stop fire (such as fire extinguishers), devices meant to resist fire (such as fire doors), and devices that frequently caused fire (like wires used for electrical installations). This work soon expanded, and throughout the twentieth century, UL certified many pivotal consumer technologies, such as vacuum cleaners, televisions, microwaves, personal computers, and more. UL published its first standard, "Tin Clad Fire Doors", in 1903. In 1906, UL established

1457-696: The electrical code standard defined by National Electrical Code was developed since current engineering standards and code requirements do not adequately address the unique situations arising during D&D activities at U.S. Department of Energy (DOE) facilities. The additional guidance is needed to clarify the current electrical code for these situations. The guidance document provides guidance on how to interpret selected articles of NFPA 70, “National Electrical Code” (NEC), in particular certain articles within Article 590, “Temporary Power,” for D&D electrical activities at DOE sites. The NEC also contains information about

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1504-419: The entire code, plus additional illustrations and explanations, and helpful cross-references within the code and to earlier versions of the code. The explanations are only for reference and are not enforceable. Many NEC requirements refer to "listed" or "labeled" devices and appliances, and this means that the item has been designed, manufactured, tested or inspected, and marked in accordance with requirements of

1551-892: The first 8 chapters contain numbered parts, articles, sections (or lists or tables), item, specifics, inclusions/exclusions, precise inclusion/exclusion, italicized exceptions, and explanatory material – explanations that are not part of the rules. Articles are coded with numerals and letters, as ###.###(A)(#)(a). For example, 805.133(A)(1)(a)(1), would be read as "article 805, section 133, item (A) Separation from Other Conductors, specific (1) In Raceways, cable Trays, Boxes,... inclusion (a) Other Circuits, precise inclusion (1) Class 2 and Class 3...." and would be found in Chapter 8, Part IV Installation Methods Within Buildings. For internal references, some lengthy articles are further broken into "parts" with Roman-numerals (parts I, II, III, etc.). Each code article

1598-406: The front of the code book. The NESC contains the procedure and time schedule for revising the NESC, which are described in the back of the code book. The NESC has an interpretation committee that issues formal interpretations. The process for obtaining a formal interpretation is outlined in the front of the code book. The NESC is currently published on a 5-year cycle. Urgent safety matters that require

1645-510: The heating effects of solar radiation. Electrical Construction and Maintenance Magazine, Conductors for General Use, Chapter 3 Articles in NEC, starting with Article 342 This section is expected to be modified to include cables in future editions. In certain situations, temperature rating can be higher than normal, such as for knob-and-tube wiring where two or more load-carrying wires are never likely to be in close proximity. A knob-and-tube installation uses wires suspended in air. This gives them

1692-441: The listing agency. To be listed , the device must meet testing and other requirements set by a listing agency such as Underwriters Laboratories (UL), SGS North America , Intertek (Formerly ETL), Canadian Standards Association (CSA), or FM Approvals (FM). These are examples of "national recognized testing laboratories" (NRTL) approved by the U.S. Department of Labor's Occupational Safety and Health Administration (OSHA) under

1739-627: The local code was not updated. In the United States , anyone, including the city issuing building permits, may face a civil liability lawsuit for negligently creating a situation that results in loss of life or property. Those who fail to adhere to well known best practices for safety have been held negligent. This liability and the desire to protect residents has motivated cities to adopt and enforce building codes that specify standards and practices for electrical systems (as well as other departments such as water and fuel-gas systems). That creates

1786-468: The minimum number of branches, and placement of receptacles, according to the location and purpose of the receptacle outlet. Ten important items in Article 210 have been summarized in a codebook. Feeder and branch circuit wiring systems are designed primarily for copper conductors . Aluminum wiring is listed by Underwriters Laboratories for interior wiring applications and became increasingly used around 1966 due to its lower cost. Prior to 1972, however,

1833-423: The nature of funding sources for development of the standards, which are often adopted as law, but created without taxpayer dollars. NFPA in response has pointed to its making a free version of its standards available online, albeit in a less convenient forum than the standard that is available for purchase. National Electrical Safety Code The National Electrical Safety Code ( NESC ) or ANSI Standard C2

1880-419: The new edition. The NEC is also available as a restricted, digitized coding model that can be read online free of charge on certain computing platforms that support the restricted viewer software; however this digital version cannot be saved, copied, or printed. In the United States , statutory law cannot be copyrighted and is freely accessible and copyable by anyone. When a standards organization develops

1927-403: The new receptacles must be marked with 'No equipment ground' and 'GFCI Protected' . The 1999 Code required that new 120/240 volt receptacles, such as those for electric ranges and dryers, be grounded also, which necessitates a fourth slot in their faces. Changes in standards often create problems for new work in old buildings. Unlike circuit breakers and fuses, which only open the circuit when

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1974-484: The official definition of HAZLOC and the related standards given by the Occupational Safety and Health Administration and dealing with hazardous locations such as explosive atmospheres. The NEC is available as a bound book containing approximately 1000 pages. It has been available in electronic form since the 1993 edition. Although the code is updated every three years, some jurisdictions do not immediately adopt

2021-533: The parent company of a for-profit company in the U.S named UL LLC, a limited liability corporation. The for-profit company took over the product testing and certification business. In 2022, the company revised their go-to-market strategy to include three separate organizations - UL Solutions, UL Standards & Engagement, and UL Research Institutes. UL Solutions became a public company via an initial public offering in April 2024 raising around $ 950   million, valuing

2068-450: The parent company of a for-profit company in the U.S. named UL LLC, a limited liability company , which took over the product testing and certification business. On June 26, 2022, the companies rebranded into three distinct organizations that make up the UL enterprise. The company is one of several companies approved to perform safety testing by the U.S. federal agency Occupational Safety and Health Administration (OSHA). OSHA maintains

2115-428: The reputation of these listing agencies, the "authority having jurisdiction" ( or "AHJ" – as they are commonly known) usually will quickly accept any device, appliance, or piece of equipment having such a label, provided that an end user or installer uses the product in accordance with manufacturer's instructions and the limitations of the listing standard. However, an AHJ, under the National Electrical Code provisions, has

2162-417: The requirements of 29 CFR 1910.7. Only a listed device can carry the listing brand (or "mark") of the listing agency. Upon payment of an investigation fee to determine suitability, an investigation is started. To be labeled as fit for a particular purpose (for example "wet locations", "domestic range") a device must be tested for that specific use by the listing agency and then the appropriate label applied to

2209-561: The time. In May 1893, Merrill moved to Chicago to work for the Chicago Fire Underwriters' Association. His task was to inspect the city's fire alarm systems. He was also sent to the 1893 World's Fair to inspect the Fair's electrical installations and the Palace of Electricity. In order to determine and mitigate risk in his role as an electrical inspector, Merrill found it necessary to conduct tests on building materials and electrical components. Upon seeing

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