Wiring a Twist Lock 125V Plug

Twist lock plugs and receptacles give a level of security for devices, which are not accidentally unplugged. To lock it in place, the plug must be inserted into the receptacle and twisted. You will also need to push the plug in and turn it backward to remove the plug from the receptacle. It is easy to wire a twist lock but you will also need to follow the steps for proper wiring. Some plugs and receptacles are not grounded and the wiring is polarized. The cords are two or three separate insulated wires encased in a light rubber or plastic sheath. Here are the steps on how to wire the twist lock.

You will need:

  1. 2 Or 3 Wire Cord
  2. Stranded Wire Stripper
  3. Flat-Head/Phillips Screwdriver



  1. First, remove the two screws that hold the insulated plug case together and to expose the terminals. Search for the gold or brass hot terminal, terminal with green ground screw and the silver neutral terminal. Use a screwdriver to loosen all the three terminal screws.
  2. Then, expose the insulated conductors by stripping one inch of sheathing from the cord. Strip half to ¾ inch of insulation from each conductor.
  3. Twist the stranded conductor lightly to hold it together. Turn the green ground wire clockwise ¾ of a turn around the green grounding screw and use a screwdriver to tighten it.
  4. Connect the white neutral wire to the silver terminal screw, and apply the same way to the black or colored wire is connected to the brass terminal screw.
  5. Next, bring the cord out the back of the plug through the strain relief hole and close the plug case. With one hand, hold the case closed while you tighten the case screws using your other hand.
  6. Make sure that you screw them firmly so the plug case will grip the cord tightly to prevent the cord from being pulled out in the future. For medical equipment that uses twist lock plugs, it is best to take the equipment to a qualified repair or technician for proper wiring.

Image Credit:

Flickr CC

Additional Reading:

IEC 60906-2 Ed. 2.0 b:1997, IEC system of plugs and socket-outlets for household and similar purposes – Part 2: Plugs and socket-outlets 15 A 125 V a.c.