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Thread: Transformer not used to capacity

  1. #21
    Join Date
    Jul 2005
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    Tennessee
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    Quote Originally Posted by DrSparks View Post
    Yup but remember you can round up to the next higher standard ocpd rating if under 800a

    Sent from my A574BL using Tapatalk
    Quote Originally Posted by petersonra View Post
    only on the secondary side.
    I believe that is incorrect. 240.21 (C)

    (C) Transformer Secondary Conductors. ....... The provisions of 240.4(B) shall not be permitted for transformer secondary conductors.

    Next size up on primary is OK, not on secondary
    At my age, I'm accustomed to restaurants asking me to pay in advance, but now my bank has started sending me their calendar one month at a time.

  2. #22
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    Jun 2004
    Location
    Cherry Valley NY, Seattle, WA
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    Quote Originally Posted by augie47 View Post
    I believe that is incorrect. 240.21 (C)

    (C) Transformer Secondary Conductors. ....... The provisions of 240.4(B) shall not be permitted for transformer secondary conductors.

    Next size up on primary is OK, not on secondary
    There may have been some confusion about the transformer protection vs conductor protection. In post #17 I was referring to transformer protections. I understand Bobs response now.
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

  3. #23
    Join Date
    Jun 2014
    Location
    Madison, WI, USA
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    346
    Quote Originally Posted by augie47 View Post
    I believe that is incorrect. 240.21 (C)

    (C) Transformer Secondary Conductors. ....... The provisions of 240.4(B) shall not be permitted for transformer secondary conductors.

    Next size up on primary is OK, not on secondary
    Is that 2017? My 2014 doesn't have a section C. WI is still on 2011 lol

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    Tell me and I forget. Teach me and I remember. Involve me and I learn.

  4. #24
    Join Date
    Jul 2005
    Location
    Tennessee
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    Quote Originally Posted by DrSparks View Post
    Is that 2017? My 2014 doesn't have a section C. WI is still on 2011 lol

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    In 2017 it's on Pg 97, in 2014 it's on Pg 99.
    You must have a special DrSparks addition
    At my age, I'm accustomed to restaurants asking me to pay in advance, but now my bank has started sending me their calendar one month at a time.

  5. #25
    Join Date
    Feb 2003
    Location
    Wisconsin
    Posts
    9,888
    Quote Originally Posted by sameguy View Post
    If I recall, transformers run best when loaded to 80% &+.
    For the past decade or so, the DOE requirements for transformers requires their 'efficient operating point' to be designed for 35% loading.
    Just because you can, doesn't mean you should.

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