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ANSI C37.51 3rd Edition, January 1, 2003
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For Switchgear - Metal-Enclosed Low-Voltage AC Power Circuit Breaker Switchgear Assemblies-Conformance Test Procedures
Includes all amendments and changes through Reaffirmation Notice , 2010
Additional Comments: FREE PDF * INCORPORATES ERRATA: 02/2011
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ANSI/NEMA MW 1000, 2014
This Standard is a conformance testing standard optionally applicable to all metal-enclosed low-voltage ac power circuit breaker switchgear assemblies designed, tested, and manufactured in accordance with ANSI/IEEE C37.20.1-2002, Metal-Enclosed Low-Voltage AC Power Circuit Breaker Switchgear. This standard covers selected tests to demonstrate conformance of the basic switchgear section (which includes the structure, circuit breaker compartments, instrument compartments, buses, and internal connections) with Section 6, Tests, of ANSI/IEEE C37.20.1-2002. See ANSI/IEEE C37.20.1-2002 for assigned ratings and usual service conditions.


LV switchgear assemblies usually include control and instrumentation components unique for the application that are not individually evaluated under this standard. However, these components, when utilized in circuits that obtain their energy from primary sources within the LV switchgear, must be suitably protected in accordance with 4.2.

NOTE—In this standard, the use of the term "LV switchgear" shall be considered to mean "metal-enclosed low-voltage alternating current power circuit breaker switchgear assemblies." The use of the term "circuit breaker" shall be considered to mean "low voltage alternating current power circuit breaker," unless qualified by other descriptive terms.


This standard does not cover equipment intended for use in installations under the exclusive control of electric utilities for the purposes of communication or metering, or for generation, control, transformation, transmission, and distribution of electric energy located in buildings used exclusively by utilities for such purposes, or located outdoors on property owned or leased by the utility or on public highways, street, roads, and the like, or located outdoors by established rights on private property.

NOTE—An electric utility is an entity that is overseen by a public utility commission, a public service commission, or other regulatory agency having jurisdiction for such installations.


This standard specifies the tests that shall be performed to demonstrate that the LV switchgear being tested conforms with the ratings assigned to it and meets the mechanical and electrical performance requirements specified in ANSI/IEEE C37.20.1-2002.