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What is the max amperage @120v that Romex 12/2 solid strand wire can take?

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  • What is the max amperage @120v that Romex 12/2 solid strand wire can take?

    Hey guys, I recently got a bunch of Romex 12/2 yellow solid strand wire on clearance at Walmart. I plan to use a bunch wiring my attic, but that's not the issue. I also am building a work bench and would like to be able to pull 20 amps @120v. I'll buy heavier gauge but would like to avoid it if possible. Also if not heavy enough, does anyone know if running parallel wire is against code in NY? Thanks in advance for the feedback.

  • #2
    You can?t double up wire to increase amperage/current rating. 12g is the correct wire size for 20amp service. Now, when figuring a constant load, a circuit should limited to 20% less than the amp rating. If you have a tool with a 20amp draw, it should be on a 30amp circuit.


    • #3
      12 gauge wire is usually protected with a 20 amp breaker, in home construction,
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      • #4
        Joshua, be careful. Please read and understand the code requirements and they're exceptions. Visit several forums that address this specific question in order to get a better picture of what the code means. Alphacowboy lays it for you in simple terms but try to understand what this means in the a typical situation. BHD Is generally correct on breaker size however they're are exceptions to that as well. Don't make changes until you cleared this all up in your planning and understand it well.

        It also might be a good time to review the procedures for solid makeups, many of us put a wire nut on a give it a few twist's. It's not that simple, and they're are many guys here that will help you out with these and other mundane but very important details.


        • #5
          No such thing as "solid stranded wire" Lol
          Read up on chapter 3 wiring methods. For instance use runner boards in attic to span across rafters in attic.
          Also read up where Nm cable is prohibited. For instance exposed areas.

          Also read up on when cable amperage must be derated. For instance bundling and ambient temp.