scope:

This standard describes the application procedures for selecting and adjusting low-voltage overcurrent protective devices to achieve selective coordination.

Products and Applications Included

This standard covers the installation of low-voltage overcurrent protective devices rated 1000 volts and less, for selective coordination in electrical distribution systems for residential, commercial, and industrial applications. This applies to:

• Low voltage power circuit breakers

• Fuses

• Molded case circuit breakers

Products and Applications Excluded

This standard does not apply to:

• Overcurrent protective devices rated more than 1000 V

• Protective relays

• Protection of conductors, transformers, motors or other equipment

Regulatory and Other Requirements

All information in this publication is intended to conform to the National Electrical Code (ANSI/NFPA 70). Installers shall follow the NEC, applicable state and local codes, manufacturer instructions, and contract documents when installing overcurrent protective devices.

Only qualified persons as defined in the National Electrical Code familiar with the construction, installation, and operation of overcurrent protective devices shall perform the technical work described in this publication. Administrative functions such as receiving, handling, and storing overcurrent protective devices and other tasks may be performed under the supervision of a qualified person. All work shall be performed in accordance with NFPA 70E, Standard for Electrical Safety in the Workplace.

General requirements for installing electrical products and systems are described in NECA 1, Standard for Good Workmanship in Electrical Construction (ANSI). Other NEIS provide additional guidance for installing particular types of electrical products and systems. A complete list of NEIS is provided in Annex B.

Mandatory Requirements, Permissive Requirements, Quality and Performance Recommendations, Explanatory Material, and Informative Annexes

Mandatory requirements in manufacturer instructions, Codes or other mandatory Standards that may or may not be adopted into law, are those that identify actions that are specifically required or prohibited and are characterized by the use of the terms "must" or "must not," "shall" or "shall not," or "may not," or "are not permitted," or "are required," or by the use of positive phrasing of mandatory requirements. Examples of mandatory requirements may equally take the form of, "equipment must be protected . . .," "equipment shall be protected . . .," or "protect equipment . . .," with the latter interpreted (understood) as "(it is necessary to) protect equipment . . ."

Permissive requirements of manufacturer instructions, Codes or other mandatory Standards that may or may not be adopted into law, are those that identify actions that that are allowed but not required, or are normally used to describe options or alternative means and methods, and are characterized in this Standard by the use of the terms "may," or "are permitted," or "are not required."

Quality and performance recommendations identify actions that are recommended or not recommended to improve the overall quality or performance of the installation and are characterized by the use of the terms "should" or "should not."

Explanatory material, such as references to other Codes, Standards, documents, references to related sections of this Standard, information related to another Code, Standard, or document, and supplemental application and design information and data, is included throughout this Standard to expand the understanding of mandatory requirements, permissive requirements, and quality and performance recommendations. Such explanatory material is included for information only, and is identified by the use of the term "NOTE," or by the use of italicized text.

Non-mandatory information and other reference standards or documents relative to the application and use of materials, equipment, and systems covered by this Standard are provided in informative annexes. Informative annexes are not part of the enforceable requirements of this Standard, but are included for information purposes only.