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Thread: disconnect for transformers

  1. #1

    disconnect for transformers

    can't seem to find where a disconnect would be required on the primary side of the transformer. i know about the requirements on the secondary side of the transformer. the main for the transformer now is three floors above the transformer.
    thanks

  2. #2
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    You can't find it because it is not there. You have to have overcurrent protection on the primary windings, the primary feeder, the secondary windings, and the secondary conductors. A single circuit breaker on the primary and one on the secondary can between them do all those jobs. But there is no requirement for a local disconnecting means.
    Quote Originally Posted by boatfull View Post
    The main for the transformer now is three floors above the transformer.
    That is allowable.

    Charles E. Beck, P.E., Seattle
    Comments based on 2014 NEC unless otherwise noted.

  3. #3
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    This requirement will be modified in the 2011 NEC.

    450.14 Disconnecting Means. Transformers, other than
    Class 2 or Class 3 transformers, shall have a disconnecting
    means located either in sight of the transformer or in
    a remote location. Where located in a remote location,
    the disconnecting means shall be lockable, and the location
    shall be field marked on the transformer.
    Rob

    Chief Moderator

    All responses based on the 2011 NEC unless otherwise noted

  4. #4
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    Quote Originally Posted by infinity View Post
    This requirement will be modified in the 2011 NEC.

    This is one of the changes in the '11 that I see costing some contractor a ton of money.
    Instructor, Industry Advocate

  5. #5
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    Quote Originally Posted by Pierre C Belarge View Post
    This is one of the changes in the '11 that I see costing some contractor a ton of money.
    At first I thought that too but then I read it again. Since most disconnects are capable of being locked in the open position all the contractor would need to do is comply with the transformer labeling requirement. Not really a big thing.
    Rob

    Chief Moderator

    All responses based on the 2011 NEC unless otherwise noted

  6. #6
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    Quote Originally Posted by Pierre C Belarge View Post
    This is one of the changes in the '11 that I see costing some contractor a ton of money.
    Not with a breaker locking means.
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  7. #7
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    I was describing the contractors who do not pay attention to the NEC and the inspector comes along and tells them they need a disconnect......
    Instructor, Industry Advocate

  8. #8
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    Quote Originally Posted by Pierre C Belarge View Post
    I was describing the contractors who do not pay attention to the NEC and the inspector comes along and tells them they need a disconnect......
    ....... and they blindly obey without looking it up, or asking for an article.
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  9. #9
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    Quote Originally Posted by LarryFine View Post
    ....... and they blindly obey without looking it up, or asking for an article.
    I cannot speak for other areas, but by me, there are a lot of sheep in electrician's clothing.





    **sometimes I crack myself up!!!
    Instructor, Industry Advocate

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