How to Wire a Plug

Yes, there is a right way and one or more wrong ways to wire a two prong electrical plug. It’s simple to do correctly though.

  • Unplug the cord. It should go without saying, but we’re saying it anyway.
  • If you’re replacing an existing plug, there are two possibilities:
    • The existing plug is molded on and cannot be disassembled. In this case, cut the wire cleanly at the old plug.
    • The existing plug has one or more screws in it and be disassembled. In this case, disassemble and remove the old plug. Note which wire is connected to the neutral or wider blade on the plug if applicable.
  • Disassemble the new plug. It will have one or more screws in it, which may be hidden by a cardboard insert over the prongs.
  • Loosen the terminal screws in the new plug if it has screw terminals. They shouldn’t easily come all the way out, they should stop at some point. Don’t remove them all the way, or screw them back in a little if you already did :)
  • Route the wire through the new plug. This may mean threading it through the back of the plug, or laying into channels if the plug is a clam-type of assembly.
  • There needs to be some type of strain relief to hold the cable firm in the plug. Some people (surely not you) like to pull things out of the wall by their cords. You don’t want this to result in pulling the cord out of the plug, so you need a mechanical connection which protects and isn’t the same as the electrical connection.
    • Some plugs have a strain relief built into them, maybe around the cord as it exits the plug or through a system of channels in the plastic.
    • Some plugs don’t have any strain relief built into them. In this case, separate the two wires (on the prong side) and tie an Underwriter’s Knot in them to prevent the cord from being pulled out the plug.
  • Identify the neutral wire. Of the two insulated wires in your electrical cord, one of them will be marked in some manner so you can differentiate between them. The insulation on one wire may have a small ridge in it, or the insulation color may be different, or one may have a stripe on it, or the color of the wires themselves may be different.  The wire with the ridge, or stripe, or the white insulation, or the silver colored wire (if one is copper colored and one is silver colored) is the neutral wire. If you are replacing an existing plug, it will be the one which was connected to the wider blade on the plug.
  • Strip your wire in preparation for wiring – see our article on that topic at the link
  • Assuming your new plug uses screw terminals, form a hook in the stripped part of each wire.
Wiring a two prong plug

Wiring a two prong plug

 

  • The wire you identified as the neutral wire gets wrapped around the neutral terminal screw. This is the silver screw if one is silver and one is brass colored. It is the screw which connects to the wider blade of the plug. Wrap the wire around it, and screw the terminal in tight on the wire. Be sure that none of the strands of the wire end up sticking out. It might help to use a small flat-tip screwdriver to push them back under the screw head as you tighten it. No little whiskers should protrude from underneath the screw. Also, you want the insulation to come up to the screw, but not go under it. You want no bare wire exposed, but if the insulation goes under the screw it won’t be able to tighten down on the bare wire.
  • Now connect the other wire (called the hot wire) to the other screw terminal.
  • Make sure both connections are tight and any bare wire cannot touch another part of the plug or the other wire.
  • Re-assemble the plug
  • If you do have a multi-meter or continuity tester, you can check the connection by putting one probe on each blade of the plug. There should be no continuity. If there is, check to be sure it isn’t something on the other end of the cord, like a lamp which is switched to the on position. Otherwise, continuity between the blades means something is shorted somewhere, so don’t plug it in until you can identify the cause and clear it.