How to Find the Correct Wire Connector Nut Size

While doing electrical work it is important that the connections are safe and secure. Wire nuts are insulated plastic connectors with a metal coil that are twisted onto the bare, or stripped, ends of two or more wires to complete a circuit. These wire connector nuts can be purchased in many sizes. The color of the connector indicates the size of the wiring that can be connected using that particular nut. The correct combinations are written on the side of the wire nut package. However, manufacturers use their own color code, which is not standard for all brands of wire nuts.

Wire connectors nuts.
  1. Determine the gauge of the wires to be connected. Wire gauge indicates the diameter of the wire. The most common residential wiring is called sheathed wiring, where two or more insulated wires are enclosed in a plastic outer covering. The gauge of the wire is printed on the sheathing. If the numbers are illegible or behind the wall, wire strippers have gauges on the handles or near the cutting edge. A metal circular wire gauge is also available at home improvement stores.

  2. Pliers and wire cutter
  3. Strip one-half to three-fourths of an inch of insulation from the end of the wires to be connected. If the wires are bent or curled on the end, cut the curved piece off using a wire cutter. Place the wires that are to be joined together next to each other with the bare ends lined up. Twist the wires in a clockwise direction using the pliers.

  4. Read the chart on the package of wire nuts to determine the correct size to use. The chart will indicate the minimum and maximum number of wires that can be joined together using the specified connector.

    Once the correct wire nut is selected, twist the nut onto the spliced wires until no wire is exposed. Tug on the wires to test the splice. If any of the wires come loose, redo the splice so it is secure. Wrap electrical tape around the nut and approximately one inch up the spliced wires.


  • Be sure to turn off power to the circuit at the circuit breaker or fuse box before working on any wiring.
  • Special connectors are needed when splicing aluminum wiring. Check with a home improvement store for the proper connectors to use.