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Thread: Insulated Throat EMT Connectors and 300.4(G)

  1. #1
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    Insulated Throat EMT Connectors and 300.4(G)

    Having a discussion recently as to whether or not an EMT connector with an insulated throat meets the intent of 300.4(G) (when used with conductors #4 and larger) in lieu of a plastic bushing. My opinion is that they are complaint because they meet the requirement of the last sentence because they are fastened in place.

    300.4(G) Insulated Fittings. Where raceways contain 4 AWG or larger insulated circuit conductors, and these conductors enter a cabinet, a box, an enclosure, or a raceway, the conductors shall be protected by an identified fitting providing a smoothly rounded insulating surface, unless the conductors are separated from the fitting or raceway by identified insulating material that is securely fastened in place.
    Rob

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    All responses based on the 2014 NEC unless otherwise noted

  2. #2
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    Quote Originally Posted by infinity View Post
    Having a discussion recently as to whether or not an EMT connector with an insulated throat meets the intent of 300.4(G) (when used with conductors #4 and larger) in lieu of a plastic bushing. My opinion is that they are complaint because they meet the requirement of the last sentence because they are fastened in place.



    If I didn't know what a plastic bushing was, I'd say you just described the fitting in the picture.

    JAP>

  3. #3
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    If I were an inspector, I'd let the fitting you pictured slide... but on a personal level I don't think they should be permitted to be compliant. I say this because there is no rounded throat on that fitting, and deeper into the fitting, the fitting metal is not separated from the conductors by the insulating throat.

    Compare to rounding of this throat...

    I will have achieved my life's goal if I die with a smile on my face.

  4. #4
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    I would guess that the fitting in post #1 would keep the conductors from touching the actual fitting. The rounded insulating surface refers to an external bushing so I would see either of those pictured as being compliant.
    Rob

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    All responses based on the 2014 NEC unless otherwise noted

  5. #5
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    The fitting insulation is rounded in post #1.
    It just has a smaller radius that the fitting in post #2.
    There is no requirement for the rounded radius.
    Tim
    Master Electrician
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    Yesterday's Technology at Tomorrow's Prices

  6. #6
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    Quote Originally Posted by tkb View Post
    The fitting insulation is rounded in post #1.
    It just has a smaller radius that the fitting in post #2.
    There is no requirement for the rounded radius.
    I think the rounding should at least be discernible by the naked eye...
    I will have achieved my life's goal if I die with a smile on my face.

  7. #7
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    Quote Originally Posted by Smart $ View Post
    I think the rounding should at least be discernible by the naked eye...
    There is a very discernible rounding in the red plastic of the connector shown. Unfortunately that radiused part is on the outside of the indiscernibly rounded inner edge.

  8. #8
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    Quote Originally Posted by GoldDigger View Post
    There is a very discernible rounding in the red plastic of the connector shown. Unfortunately that radiused part is on the outside of the indiscernibly rounded inner edge.
    By golly you are correct.

    The section text is of no help. I inferred the rounded surface is to be the one the conductors make contact with.
    I will have achieved my life's goal if I die with a smile on my face.

  9. #9
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    Quote Originally Posted by infinity View Post
    Having a discussion recently as to whether or not an EMT connector with an insulated throat meets the intent of 300.4(G) (when used with conductors #4 and larger) in lieu of a plastic bushing. My opinion is that they are complaint because they meet the requirement of the last sentence because they are fastened in place.



    Compliant IMO also.
    "Electricity is really just organized lightning." George Carlin


    Derek

  10. #10
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    I've used these without an external plastic bushing on some larger EMT runs and found that the internal insulated throat didn't survive the rope and nose of the cable coming through it. Typically they popped right out and if you were lucky they didn't break and could be reinstalled.
    Rob

    Moderator

    All responses based on the 2014 NEC unless otherwise noted

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