How to Connect Two Wires With a Wire Nut Connector Size Chart

Knowing how to connect two wires with a connector is critical in electrical work. Furthermore, knowing the proper method of using a wire nut as well as having access to a wire nut size chart, will be extremely helpful in the process.

Today, I will be covering the way I’ve always prepared and applied wires into a wire nut connector. this method has been field tested over the years and is widely known by experienced electricians all over the world. However, a lot of mistakes are made by homeowners and those who aren’t practicing the trade on a regular basis.

Wire Nut Size Chart

Before you jump to the connection, you must equip yourself with the right connectors. In case of home and many types of commercial and industrial wiring in North America, the standard is to use Wire Nuts. These connectors are extremely easy to use and are quite common in the industry. They are known by different names among electricians in different concentrations and areas.

Some examples of names are Marettes, Wire Nuts, Twist-On Connectors, Winged Wire Nuts, etc.

It is possible to consistently pick the right size of a connector with experience but to get you started, it’s always recommended to follow a chart. Identify the size of cables you’re dealing with and select the proper connector from the table below. Keep in mind that the number of cables, as well as their composition (stranded vs solid core), is also important.

how to connect two wires with a connector

Step 1 – Preparing The Wires

How to Connect Two Wires With a ConnectorOnce you have the right connectors on hand and a firm grasp on the type of cable you’re planning to deal with, it’s time to get started with the connection.

Begin by removing two inches of the outer insulation (if any) from the cable. By using a wire stripper, remove the insulation from each individual wire about a quarter of an inch (~1cm).

Lay the cable on a surface and identify the connections you’re looking to make. If you are planning to connect to a separate cable or set of wires, follow the step above to prepare the second cable and any other connections you are planning to make.

Step 2 – Mating The Copper

Wire Nut Connector Size ChartInexperienced electricians will often throw a wire nut on top of two copper conductors hoping that they will twist inside. Although the connectors are designed to guide the conductors in this fashion, a much more reliable connection is established by twisting them beforehand.

Simply place two or more exposed wires next to each other and twist the copper ends. By doing so, you are making sure that they will go further into the connector and stay bound for a very long time.

Warning: Using Copper & Aluminum

It’s not uncommon to see aluminum wiring in older residences and other electrical fields. Although it may seem like a good idea to leave such wires in place, a connection between copper and aluminum through a wire nut is not recommended. You will notice that with time, one of the metals will begin oxidizing and weakening the connection. Although this may last for years, this is how you get flickering lights that are extremely difficult to troubleshoot.

Step 3 – How to Use Wire Nuts

How to Connect Two Wires With a Wire Nut ConnectorOnce you’ve secured a handful of wire nuts, it becomes second nature. However, it’s not extremely obvious at first and will cause you to become frustrated.

The biggest pitfall of a wire nut connection is the orientation of the wire nut versus the twist on the wires. In other words, if you twisted the cables counter-clockwise in the previous step, the wire nut will go against the bond and “untwist” them instead of pushing them in.

If you’re looking at your wires from the top, remember to twist them in the clockwise direction and to apply the wire nut rotation in the same direction.

Common Issues While Making the Connection

I’ve seen absolutely everything in the field as an electrician. Here are some common issues people encounter when connecting two or more wires with a wire nut.

  • Wrong Wire Nut Size – You need to pay attention to the wire nut sizing chart posted above. Too large or too small of a connector will result in a poor connection which will release the cables prematurely.

  • Unstripped or Poorly Stripped Wires – Failing to remove the insulation completely from your conductors will most often result in a poor connection. Although even experienced individuals swear by sticking uninsulated wires into a wire nut, it’s definitely not the way to go based on my experience.

  • Twisting in the Wrong Direction – As mentioned above, twisting a wire nut onto cables which have been twisted in the opposite direction will result in a mess inside of the connector. Make sure that you are following the “spiral” inside of the connector with the twisting motion. You can definitely reuse the wire nut if you failed here.

  • Excessive Number of Wires – It’s quite common to see over 5 wires inside of a single wire nut. You’re creating a hazard by doing so. Remove such connection and consider a terminal strip for such a junction. I would not recommend using a wire nut for more than 3 wires.

Conclusion on How to Connect Two Wire with a Connector

Connecting wires is at the core of electrical work. You will encounter this task while installing lights, heaters, outlets and any other appliance within residences, commercial or industrial spaces. Although it may seem simple, it’s important to take a moment to review the reight steps of installing a wire nut.

A critical part of the process is selecting the right wire nut size from the chart provided above. Once that is done, you can safely remove the insulation from your wires, twist the pair and apply the wire nut creating a secure connection.