Answering questions that may arise related to the meaning of portions of an IEEE standard concerning specific applications.

IEEE Standards Interpretation for IEEE Std C37.74™-2003 IEEE Standard Requirements for Subsurface, Vault, and Pad-Mounted Load-Interrupter Switchgear and Fused Load-Interrupter Switchgear for Alternating Current Systems Up to 38 kV

Copyright © 2004 by the Institute of Electrical and Electronics Engineers, Inc. 3 Park Avenue New York, New York 10016-5997 USA All Rights Reserved.

Interpretations are issued to explain and clarify the intent of a standard and do not constitute an alteration to the original standard. In addition, interpretations are not intended to supply consulting information. Permission is hereby granted to download and print one copy of this document. Individuals seeking permission to reproduce and/or distribute this document in its entirety or portions of this document must contact the IEEE Standards Department for the appropriate license. Use of the information contained in this document is at your own risk.

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26 February 2004

Interpretation Request #1
Topic: (1) Definition of "vault"

Please provide guidance as to where equipment covered by this standard is to be installed and how it's to be physically protected when installed in indoor locations. We need an explicit definition and explanation of a "vault" as used in C37 .74 and in manufacturers installation instructions.

Interpretation Response
The IEEE Standards are written to help assure safe and reliable application, installation, operation and maintenance of equipment for the electric power systems. As such, they are written in a specific standard IEEE format and cannot be written to follow a UL format.

The engineering application of the equipment stated in your letter is that which would normally be within the area of consultant services; i.e., not in the IEEE standards. Also, of course, all installations must follow the national, state, and local code requirements as applicable.

The following is the definition of a vault from the IEEE Standard Dictionary of Electrical and Electronics Terms, IEEE Std 100™-1997. Please note that this definition is also in the National Electric Safety Code®, C2®-1997. vault A structurally solid enclosure above or below ground with access limited to personnel qualified to install, maintain, operate, or inspect the equipment or cable enclosed. The enclosure may have openings for ventilation, personnel access, cable entrance, and other openings required for operation of equipment in the vault. (NESC®) C2-1997.