How to Wire a Plug

 



Why It’s Important to Connect Hot and Neutral Wires Correctly

 

You can attach the wires to a plug without paying attention to hot and neutral, and your plug will operate without anything seeming wrong. However, if your plug is on the other end of a wire from a socket or other electrical item, in order for the hot and neutral wiring to operate in a way that protects you, you must wire the plug correctly with regard to hot and neutral. For example, if your plug is on the other end of the wire from a socket, the chance of getting a shock when handling the socket – especially while changing the bulb -- is higher if you don’t connect the hot and neutral wires correctly on both ends.

Electricity creates a circuit through the bulb by running through the metal tab at the bottom of the socket, where the bulb sits, through the bulb, and through the metal threads where the bulb is screwed in.

When wired properly, the metal threads will never be “hot” or give you a shock, whether the switch is on or off. When wired incorrectly, the threads – and any metal touching the threads, including the outside of the socket, if it is conductive metal, or the threads of a light bulb – can give you a shock whether the switch is on or off. Therefore, it is important to follow the instructions for the hot and neutral wires carefully for both the plug and the socket.

However, some plugs are non-polarized. A polarized plug will have one prong wider than the other, which is the neutral, and usually silver-colored prong. The hot prong will be narrower and usually gold-colored. With a non-polarized plug, you can wire either wire to either prong.

 

Wiring the Plug

 

  1. VERY IMPORTANT: Make sure any electrical device being worked on is not connected to electricity. Turn off the circuit breaker, remove the fuse, or unplug the device before starting. If you have any questions about the safety of what you are doing, please contact an electrician rather than doing the job yourself.

  2. Cut the wire to the length you want plus 10 inches.

  3. Use a 1.5” piece of self-fusing silicone tape to tape the cloth braid down 2.5 inches from the end that will be attached to the plug. The silicone tape sticks to itself (a little like Saran Wrap) but isn’t sticky. It will stay on best if you stretch it as you wind it around the wire. Try to keep the taped area as small as possible (going around in the same place) and not more than two or three layers of tape deep. This will make it so that you can keep the tape hidden. If the wire is twisted pair wire, also go around both wires with the tape, holding the twist in place in addition to preventing the cloth from fraying.

  4. Cut the braid (cotton or rayon) off the wire from the end of the wire to the tape. Use the finest scissors you have to snip vertically along the braid, taking care not to cut into the plastic at all. When you get to the tape, trim up all loose threads.

  5. Strip ½” of the plastic off the ends of the wire.

     



    A wire stripper is the best tool for this because it doesn’t cut the copper, just the insulating plastic around the copper. Make sure you use the slot in the stripper that matches the gauge of the wire you are using.

     



  6. Now put the cap of the plug over the wire, making sure the end where the prongs go is facing the end of the wire that you are preparing to wire to the plug.

  7. If you are using the rubber or Bakelite rectangular plug or any of the button plugs, there is not enough room for an underwriter's knot in the plug, so you have to skip this step. You might want to make the leads shorter if you are not making the knot so there is not as much stripped wire that you have to fit in the shell.

    If you are using any of the other plugs (the Round Plug with Neck is the only one we have currently that will fit the knot, tie an underwriter’s knot in the wire. This helps keep the wires connected to the plug even with some tension applied to the plug. The picture on the left is intended to show how to make the knot. The picture on the right shows the knot in the taped cloth-covered wire. If your plug is a button plug, you will need to make the knot really tight to be able to fit it in the cap of the plug along with the interior.

     

       



  8. Twist the exposed end of the neutral wire so that the strands of copper are firmly twisted together. See the chart below for which wire is hot and which is neutral.


    Identifying the Hot, Neutral, and Ground Wires
      Hot Neutral Ground
    Parallel Cord smooth wire ribbed wire none
    Twisted Pair *plain (no stripe) wire *striped wire none
    Three-Conductor black wire white wire green wire
    Plug/Socket narrow prong/gold screw wide prong/silver screw n/a


    * This is a Sundial Wire convention. In non-Sundial Wire, the hot wire is black and the neutral white. Sundial Wire uses the stripe/no-stripe convention so that the color of the plastic does not show through the braid. Also, in some of our wires, there is no striped wire, but a beige wire, which is hot, and a white wire, which is neutral.

  9. Make a little hook out of the end of the wire.

     



  10. Put the hook of the neutral wire over the silver screw in the plug, with the hook going clockwise around the screw.

  11. Tighten the screw.

  12. Do the same with the hot wire and the gold screw.

  13. Slip the cap of the plug down the wire and over the plug interior.

  14. If the plug has a yellow, screw-on interior, screw it in tight. If the plug has a cardboard cover, put that on. Note that once you put the cardboard cover on, it can be very hard to remove, so be fairly sure you won't have to remove it. (We do sell replacements, however.)