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Thread: Duplex circuit breakers

  1. #1
    Join Date
    Mar 2003
    Location
    Massachusetts
    Posts
    6

    Duplex circuit breakers

    I am currently doing an electrical study at a library that is over 100 years old. The existing panels contain duplex breakers(twin or piggyback). What does the NEC say about the installation and use of these breakers? And more importantly, where in the code is this found? I've looked for a while but for some reason I am not having any luck.

  2. #2
    Join Date
    May 2003
    Location
    Salt Lake City, Utah
    Posts
    5,319

    Re: Duplex circuit breakers

    I don't beleive you will find it in the NEC. These are governed by the manufacturer of the panelboard. 110.3(B). Is there a more specific question that you have in mind?
    Ryan Jackson, Salt Lake City
    Inspector, Instructor

  3. #3
    Join Date
    Mar 2003
    Location
    Massachusetts
    Posts
    6

    Re: Duplex circuit breakers

    more specific? I beleive I recall something about no more than 20% (maybe it was 10%) of the breakers in a panel can be duplex breakers.

  4. #4
    Join Date
    May 2003
    Location
    Salt Lake City, Utah
    Posts
    5,319

    Re: Duplex circuit breakers

    In many panelboards, only the bottom 1/3 of the panel may contain these breakers. However, there are panels that will accomodate these throughout the panel. Take a look (if you can) at the information in the panel provided by the manufacturer. You may see a number such as "16-24". This would mean the panel contains 16 spaces but can have up to 24 circuits.
    Ryan Jackson, Salt Lake City
    Inspector, Instructor

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