90.1 Purpose : www.NECcode.com Mike Holt Enterprises, Inc.© 1 90.1 Purpose (A) Practical Safeguarding. The purpose of the NEC is to ensure that electrical systems are installed in a manner that protects people and property by minimizing the risks associated with the use of electricity.
Slide 2 : www.NECcode.com Mike Holt Enterprises, Inc.© 2 90.1 Purpose (B) Adequacy. The Code contains requirements to ensure a safe electrical installation. Installation installed in compliance with the NEC, should be essentially free from electrical hazards.
The NEC is a safety standard, not a design guide, but…
90.1 Purpose : www.NECcode.com Mike Holt Enterprises, Inc.© 3 90.1 Purpose (B) Adequacy. NEC compliant installations are not always efficient, convenient, adequate for good service, or suitable for future expansion. Fig 90-1
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90.1 Purpose : www.NECcode.com Mike Holt Enterprises, Inc.© 5 90.1 Purpose (C) Intention. The Code is to be used by persons skilled and knowledgeable in electrical theory, electrical systems, and the installation and operation of electrical equipment.
It’s not a design standard or instruction manual.
90.2 Scope of NEC : www.NECcode.com Mike Holt Enterprises, Inc.© 6 90.2 Scope of NEC (A) What is Covered.
(1) Public and private premises.
(2) Carnivals and industrial substations.
(3) Conductors and equipment that connect to the utility supply.
(4) Installations used by an electric utility and electric utility buildings that are not an integral part of a utility's generating plant, substation or control center. Fig 90-4
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90.2 Scope of NEC : www.NECcode.com Mike Holt Enterprises, Inc.© 8 90.2 Scope of NEC (B) What isn't Covered.
(1) Cars, trucks, boats, ships and watercraft, planes, electric trains or underground mines.
(2) Underground and surface mining machinery.
(3) Railway power, signaling, and communications wiring.
90.2 Scope of NEC : www.NECcode.com Mike Holt Enterprises, Inc.© 9 90.2 Scope of NEC (B) What isn't Covered.
(4) Communications Utilities. Communications utility equipment under the exclusive control of the communications utility. Fig 90-5
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90.2 Scope of NEC : www.NECcode.com Mike Holt Enterprises, Inc.© 11 90.2 Scope of NEC (B) What isn't Covered.
Communications wiring and equipment not under utility control must be installed in accordance with Chapter 8. Fig 90-6
90.2 Scope of NEC : www.NECcode.com Mike Holt Enterprises, Inc.© 12 90.2 Scope of NEC (B) What isn't Covered.
(5) Electric Utilities. Installations under the exclusive control of an electric utility.
a. Service drops, service laterals, and associated metering. Fig 90-7
b. Wiring on legally established easements, rights-of-way, or property owned or leased by the electric utility. Fig 90-8
c. For the purpose of generation, transformation, transmission, distribution, or metering of electric energy.
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90.2 Scope of NEC : www.NECcode.com Mike Holt Enterprises, Inc.© 16 90.2 Scope of NEC (B) What isn't Covered.
(5) Electric Utilities.
Utility lighting on established easements or rights-of-way are NEC exempt, but lighting on private property must comply with the NEC. Fig 90-9
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90.3 Code Arrangement : www.NECcode.com Mike Holt Enterprises, Inc.© 19 90.3 Code Arrangement General Requirements: The requirements contained in Chapters 1, 2, 3, and 4 apply to all installations.
90.3 Code Arrangement : www.NECcode.com Mike Holt Enterprises, Inc.© 20 90.3 Code Arrangement Special Requirements: The requirements contained in Chapters 5, 6, and 7 apply to special occupancies, special equipment, or other special conditions. They can supplement or modify the requirements in Chapters 1 through 4.
90.3 Code Arrangement : www.NECcode.com Mike Holt Enterprises, Inc.© 21 90.3 Code Arrangement Communications Systems: Chapter 8 contains the requirements for communications systems, such as telephone, antenna wiring, CATV, and network-powered broadband systems.
Communications systems aren't subject to the requirements of Chapters 1 through 7, unless referenced in Chapter 8.
90.3 Code Arrangement : www.NECcode.com Mike Holt Enterprises, Inc.© 22 90.3 Code Arrangement Tables: Chapter 9 consists of tables necessary to calculate raceway sizing, conductor fill, and voltage drop.
90.3 Code Arrangement : www.NECcode.com Mike Holt Enterprises, Inc.© 23 90.3 Code Arrangement Annexes: Annexes aren't part of the Code.
Annex A. Product Safety Standards
Annex B. Conductor Ampacity - Engineering Supervision
Annex C. Raceway Size Tables
Annex D. Examples
Annex E. Types of Construction
Annex F. Cross-Reference Tables
90.4 Enforcement : www.NECcode.com Mike Holt Enterprises, Inc.© 24 90.4 Enforcement This Code is to be enforcement by governmental bodies that have legal jurisdiction over power, lighting, signaling circuits, and communications systems. Fig 90-11
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90.4 Enforcement : www.NECcode.com Mike Holt Enterprises, Inc.© 26 90.4 Enforcement Interpretation of the Requirements. The AHJ is responsible for interpreting the NEC, but his or her decisions must be based on a specific NEC requirement.
90.4 Enforcement : www.NECcode.com Mike Holt Enterprises, Inc.© 27 90.4 Enforcement Approval of Equipment and Materials. Only the AHJ has authority to approve the installation of equipment and materials.
The NEC doesn't require all equipment to be listed. Fig 90-12
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90.4 Enforcement : www.NECcode.com Mike Holt Enterprises, Inc.© 29 90.4 Enforcement Waiver of Requirements. By special permission, the AHJ can waive specific requirements in this Code or permit alternative methods where it's assured that equivalent safety can be achieved and maintained.
90.4 Enforcement : www.NECcode.com Mike Holt Enterprises, Inc.© 30 90.4 Enforcement Waiver of New Product Requirements. If the 2008 Code requires products that aren't yet available at the time the Code is adopted, the AHJ can allow products that were acceptable in the previous Code to continue to be used.
90.4 Enforcement : www.NECcode.com Mike Holt Enterprises, Inc.© 31 90.4 Enforcement Compliance with Listing Instructions. It's the AHJ's responsibility to ensure that electrical equipment is installed in accordance with equipment listing and/or labeling instructions [110.3(B)].
In addition, the AHJ can reject the installation of equipment modified in the field [90.7].
Article 100. Definitions : www.NECcode.com Mike Holt Enterprises, Inc.© 32 Article 100. Definitions Part I of Article 100 contains the definitions of terms used throughout the Code for systems that operate at 600V or less.
Article 100 contains the definitions terms used in two or more articles.
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Bonding Jumper, System : www.NECcode.com Mike Holt Enterprises, Inc.© 41 Bonding Jumper, System The conductor, screw, or strap that bonds the metal parts of a separately derived system to the separately derived system grounded conductor [250.28(A)]. Fig 100-?
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Bonding Jumper, System : www.NECcode.com Mike Holt Enterprises, Inc.© 43 Bonding Jumper, System The system bonding jumper provides the low-impedance path to the source to facilitate the clearing of a ground fault by opening the circuit protection device. New Graphic
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