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Thread: Two wire sizes in residential box?

  1. #1
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    Two wire sizes in residential box?

    Hello All,
    I have a nail on box for a kitchen counter top recept. The box is the end of the line for one of the two small appliance circuits and fed with #12 on a 20A GFCI recept. I am also using the box as a junction for a 15A lighting circuit, thus two #14 romex's are connected together in this box.

    The question would be if this is ok per the NEC. Wire fill in the box seems fine, but didn't know if mixing the two sizes was prohibited.

    Thank you as always.

  2. #2
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    It is fine. For sizing the EGC, it will be the larger of the two, the #12.
    "Electricity is really just organized lightning." George Carlin


    Derek

  3. #3
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    Quote Originally Posted by jumper View Post
    It is fine. For sizing the EGC, it will be the larger of the two, the #12.
    Thank you very much. Also as a side note, I use your Carlin quote all the time... spot on... cheers

  4. #4
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    Quote Originally Posted by jumper View Post
    It is fine. .......
    ....as long as maximum box fill is not exceeded.

  5. #5
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    Quote Originally Posted by wrobotronic View Post
    Hello All,
    I have a nail on box for a kitchen counter top recept. The box is the end of the line for one of the two small appliance circuits and fed with #12 on a 20A GFCI recept. I am also using the box as a junction for a 15A lighting circuit, thus two #14 romex's are connected together in this box.

    The question would be if this is ok per the NEC. Wire fill in the box seems fine, but didn't know if mixing the two sizes was prohibited.

    Thank you as always.
    Keep in mind the code change for 250.148 when your jurisdiction adopts the 2017 NEC.

    250.148 Continuity and Attachment of Equipment Grounding Conductors to Boxes. If circuit conductors are spliced within a box or terminated on equipment within or supported by a box, all equipment grounding conductor(s) associated with any of those circuit conductors shall be connected within the box or to the box with devices suitable for the use in accordance with 250.8 and 250.148(A) through (E).

  6. #6
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    Quote Originally Posted by stevenje View Post
    Keep in mind the code change for 250.148 when your jurisdiction adopts the 2017 NEC.

    250.148 Continuity and Attachment of Equipment Grounding Conductors to Boxes. If circuit conductors are spliced within a box or terminated on equipment within or supported by a box, all equipment grounding conductor(s) associated with any of those circuit conductors shall be connected within the box or to the box with devices suitable for the use in accordance with 250.8 and 250.148(A) through (E).
    What is that jibberish?

  7. #7
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    Quote Originally Posted by Sierrasparky View Post
    What is that jibberish?
    I think you meant gibberish. (rapid and incoherent talk; unintelligible chatter; jargon) You are not far off the mark seeing that what I posted was a direct quote from the 2017 NEC.

  8. #8
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    Quote Originally Posted by Sierrasparky View Post
    What is that jibberish?
    Technically, it's 'legalese'. Meaning, language written as to withstand legal scrutiny.

  9. #9
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    Quote Originally Posted by stevenje View Post
    Keep in mind the code change for 250.148 when your jurisdiction adopts the 2017 NEC.

    250.148 Continuity and Attachment of Equipment Grounding Conductors to Boxes. If circuit conductors are spliced within a box or terminated on equipment within or supported by a box, all equipment grounding conductor(s) associated with any of those circuit conductors shall be connected within the box or to the box with devices suitable for the use in accordance with 250.8 and 250.148(A) through (E).
    The "or" part of this has always been confusing for me.

    This to me makes it sound as if you can connect the EGC's together within the box and not necessarily to the box.

    JAP>

  10. #10
    Join Date
    Jan 2007
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    to me it should say "and" to the box if it was their intention for us to bond to the box in all these cases.

    JAP>

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