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Thread: Transformers

  1. #1
    Join Date
    Aug 2003


    Can anyone please help me with a technical question? I have a customer wanting to purchase a 25 KVA 1ph Encapsulated transformer. But, he needs ClassI, Div II rating. We are a manufacturers rep and sell transformers, and our factory technical "expert" cannot answer this one. To my knowledge, no manufacturer labels a dry type transfromer as ClassI, DivII.

    I believe that somewhere in the code the requirements for transformers installed in such a classified area are spelled out but don't know where to look. Can anyone help my customer out? I believe that if the winding tempature is below a certain level and the transformer is encapsulated, then it can be used in this setting. Any thoughts?


  2. #2

    Re: Transformers

    501.2 (B) states that "In Class I, Division 2 locations, transformers...shall comply with 450.21 and 450.27."

    450.21 deals with dry type transformers and 450.27 deals with oil filled outdoor transformers.

    I think your application would fall under 450.21 does not appear to need any special designation.

    Hope this helps

    Sam A. - PE
    Sam A. - P.E. :grin:
    Ann Arbor, MI

  3. #3
    Join Date
    Dec 2003

    Re: Transformers

    the transformer requires ventilation in order to cool it. a dust build up will interfere with the cooling process which could eventually cause the unit to fail and create a fire.

    if you could create a barrier wall that would eliminate the dust from the transformer, that might be enough. i would get a local pe or ahj to look at the problem.

  4. #4
    Join Date
    Mar 2003
    South Carolina

    Re: Transformers

    A Class 1, Div. 2 location is one where the hazardous liquid is handled or processed, but is normally confined, and would only be dangerous if an accident happened. Therefore, it appears your transformer would be acceptable to the NEC, however, IF I were doing design on this system, I would prefer to locate the transformer in a Non-Classified area, if possible.
    I believe Class 2 deals with dust. Class 3 deals with fibers and flyings.

  5. #5
    Join Date
    Feb 2003

    Re: Transformers

    The transformer may be encapsulated but the terminal compartment isn't so it is of my opinion that it wouldn't comply. Compare it to the terminal compartment of an EP motor which is not just a simple junction box.

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