scope:

Products and Applications Included

This recommended practice describes installation procedures for pad-mounted, sealed, self-cooled, compartmental, single- and three-phase liquid-filled distribution and power transformers with primary windings rated from 2400 Volts to 35 kV AC, nominal, and rated from 75 kVA through 5000 kVA, and associated accessories, designed for outdoor installation at grade level with underground entrance of primary and secondary conductors, and used for supplying power, heating and lighting loads for commercial, institutional, and industrial use in nonhazardous locations.

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

Products and Applications Excluded

This publication does not apply to the following:

Dry-type transformers,

Specialty transformers such as control, industrial control, instrument, current, potential, metering, buck-boost transformers, or lighting and ballast transformers,

Autotransformers,

Cast coil transformers,

Arc furnace transformers,

Rectifier transformers,

Network transformers,

Unit substation transformers, or

Transformers with more than two sets of windings.

Regulatory and Other Requirements

All information in this publication is intended to conform to the National Electrical Code

(ANSI/NFPA 70). Installers should always follow the NEC, applicable state and local codes, manufacturer's instructions, and contract documents when installing liquid-filled transformers.

Only qualified persons familiar with the construction and installation of liquid-filled transformers should perform the work described in this publication.

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