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Siemens switchgear going into place at MWAA Headquarters at Regan Airport
Siemens switchgear going into place at MWAA Headquarters at Regan Airport (photo credit: imgur.com)

The Application of Switchgear and Switchboards

One important element of good power system design is the proper selection of the distribution equipment. The choice of using either switchgear or switchboard must be based on many different criteria and the design of the power system requires thought be given to each one.

Following are insights into just a few of the differences to help in making those decisions.


Standards and Testing

Switchgear and switchboard structures are built and tested to different standards:

  • Switchgear to ANSI standard C37.20.1, UL standard 1558, and NEMA standard SG-5,
  • Switchboards to NEMA PB-2, and UL -891.

Switchgear incorporates only low-voltage power circuit breakers (LVPCB) which conform with ANSI C37.13 , NEMA SG-3 and are listed per UL-1066, whereas switchboards may include any combination of protective devices including insulated case (ICCB), molded-case circuit breakers (MCCB) listed per UL-489, fusible switches listed per U L-508 and 977 and power circuit breakers listed to UL-106 6.

Unfused switchgear is short circuit tested at 15% power factor for a full 30 cycles, while switchboards are tested at 20% power factor for only 3 cycles .

Title: The Application of Switchgear and Switchboards by Jerry Milton, GE Systems Engineer
Format: PDF
Size: 92 Kb
Pages: 5
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Difference Between Switchgear and Switchboard
The Application of Switchgear and Switchboards by Jerry Milton, GE Systems Engineer

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Page edited by E.C. (Google).

2 Comments


  1. maxim klavansky
    Mar 31, 2014

    if you consider as a switchgear a low voltage unit, what is then medium voltage unit or what is an MCC?


  2. Henn Rebane
    Oct 21, 2012

    Regarding “The Application of Switchgear and Switchboards” by Jerry Milton, GE Systems Engineer. It is a good one! But, it also illustrates the need for adding dates to the articles published in E-E-P. It references NEMA SG-5 that is obsolete, and the content of the article is restriced to low-voltage systems only.
    Henn Rebane, P.E.

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