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Thread: Splicing different gauge wires and NEC codes

  1. #1
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    Splicing different gauge wires and NEC codes

    I have an application that requires splicing two large wires and one small one and can not find much on how this should be done correctly.

    I have devised that require to 10 gauge wires and a 20 gauge wire to be splices and have have found one wire nut that is rated to join these together. I assume there are more out there but I can not seem to locate them.

    The other two cases I have are joining two 6 gauge with a 20 gauge and two 2 gauge with a 20 gauge.

    The 20 ga wire isn't load carrying it's for a voltage sensor.

    Anyone help with some appropriate hardware to splice these combinations? is the only option to splice a larger wire onto the 20 gauge and than splice to the 6 gauge or 2 gauge wires?

    Thanks

  2. #2
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    Maybe a terminal block or bar of some sort?

    I'll confess, I don't think i have ever checked a wire combination to see if it was approved for a wire nut
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

  3. #3
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    the connections are within and existing switch enclosure so there is no easy way to use a terminal block and I don't think an AHJ would approve a TB hanging in space.

  4. #4
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    For no appreciable current, I'd consider split-bolting your sensing wire to one conductor.

    Do you have a termination point nearby where you can extend and add another wire?
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  5. #5
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    I'm thinking there should be some supplementary overcurrent protection as in 240.10 close to where the connection with the larger conductor is made.
    20 gauge wire will not be adequate to trip the branch breaker if there's a short circuit and the breakers are sized to the ampacities of 10, 6, or 2 gauge wire.
    Unless there's some allowance I'm not aware of for such sensing devices.

  6. #6
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    And if supplementary overcurrent protection was connected to the large wires using the minimum gauge required for an equipment grounding conductor on the branch circuit, then that should be adequate for short circuit faults occurring anywhere along the conductors to be cleared.

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