scope:

Products and Applications Included

This standard describes the installation and maintenance procedures for single- and threephase general purpose dry-type transformers and associated accessories rated 1000 Volts AC or less, and 0.25 kVA or more.

This publication applies to indoor and outdoor, ventilated and non-ventilated, two-winding transformers used for supplying power, heating, and lighting loads for commercial, institutional, and industrial use in nonhazardous locations both indoors and outdoors.

It also covers periodic routine maintenance and troubleshooting procedures for transformers, and special procedures used after adverse operating conditions such as a short-circuit, ground-fault, or immersion in water.

Products and Applications Excluded

This standard does not include:

Transformers with one or more windings rated greater than 1000 Volts AC.

Liquid-filled transformers.

Autotransformers.

Current transformers.

Control transformers and transformers used with Class 2 and Class 3 circuits.

Dry-type transformers that constitute a component part of other apparatus and comply with the requirements for such apparatus, including an X-ray, high-frequency, or electrostatic-coating apparatus.

Transformers for sign and outline lighting, including electric-discharge lighting.

Transformers used for power-limited fire alarm circuits.

Regulatory and Other Requirements

All information in this publication is intended to conform to the National Electrical Code® (ANSI/ NFPA Standard 70). Installers shall follow the NEC^®, applicable state and local codes, and manufacturer instructions, and contract documents when installing dry-type transformers.

Only qualified persons as defined in the NEC familiar with the construction and installation of dry-type transformers shall perform the technical work described in this publication. Administrative functions such as receiving, handling and storing required in Section 4, 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. Mandatory requirements in manufacturer instructions, or of Codes or other mandatory Standards that may or 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 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. Permissive requirements of manufacturer instructions, or of Codes or other mandatory Standards that may or not be adopted into law, are those that identify actions that that are allowed but not required, 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 may not, or are permitted or are not required.

Quality and Performance Recommendations. Quality and performance recommendations identity 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 term should or should not.

Explanatory Material. Explanatory material, such as references to other Codes, Standards, or 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.

Informative Annexes. Non-mandatory information, 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.