Connecting Electrical Wires to Screw Terminals

Screw Terminal Connections On Electrical Switches and Receptacles

Light switches in the process of being wired
Quasipalm / Wikimedia Commons / Creative Commons

When connecting electrical wires to switches and receptacles, there are two ways to do it, and only one is recommended by professionals. 

Each switch and receptacle device has standard screw terminals on the sides of the device body. These are the connection terminals that are best to use, and the technique for using screw terminals is what is described in further detail in this article.

Push-In Connections

On the back side of the body of the switch or receptacle, you will also see slide-in connection holes that can allow you to simply push in the end of a bare wire to make the wire connections.

While this might seem like a very convenient way to do it, virtually no professional electricians and few experienced DIYers ever use these push-in fittings--mostly because they have had experience with these connections coming loose. While still allowed by Underwriters Laboratories (UL), these push-in connections are often not very secure to begin with, and over time, loose connections can cause arcing, pitting of the surface area around the connection, sparking and a buildup of heat. If you MUST use these push-in connections, always test the wires by tugging on them to make sure you indeed have a tight connection. 

How to Make Screw Terminal Connections

  1. First, use a pair of wire strippers or a combination tool to strip about 3/4" of wire insulation from each conductor to be connected. Take care not to nick the metal wire itself if you can help it; using the proper opening on the wire stripper will prevent this.
  1. Use a pair of long-nosed pliers to bend the exposed metal tip of the wire into a J-shaped hook This bend will allow the wire to wrap completely around the screw terminal without any insulation touching the screw head. 
  2. Now, loop the wire hook around the screw terminal in a manner so that when the screw is turned closed, the hook will tighten the wire closed, not force it open. This means, essentially, that the wire should be looped around the screw terminal in a clockwise direction as you look down at the screw head from above.  
  1. Tighten the screw terminal firmly down onto the wire. Make sure that there is no wire insulation under the head of the screw, and make sure that the wire is not resting on any part of the plastic housing of the switch or receptacle.
  2. TIP: Though not the subject of this article, always make sure you are connecting the right wires to the right screw terminals. On a receptacle, the screw terminals that are bronze or brass in color are meant to be attached to hot wires (which will usually have black or red insulation on them). The silver-colored screw terminals are meant for the neutral circuit wires (usually with white insulation), and the green colored screw terminal is meant for the circuit grounding wire, usually a bare copper wire or sometimes a wire with green insulation. 

If you have made these screw terminal connections correctly, there is a good likelihood you will not need to touch this receptacle or switch for many years. Poor electrical connections rank high as the biggest causes of electrical problems in the home. Keep you family safe and avoid electrical connection problems by mastering this simple solution of making tight, flawless electrical connections to switches and receptacles.