Wire Nut Size Chart: Guide for DIY Electrical Projects

Connecting electrical wires can be a little tricky, I get it.

It’s easy to join the wrong wires together for one thing. And on top of that, getting them to STAY together security is a must.

You usually can’t afford to make mistakes when working on an electrical project.

This is where wire nuts come in and can help keep you straight.

Wire nuts connect electric cables for in-home, commercial, and industrial wiring.

These handy connectors are also called winged wire nuts, twist-on-connectors, and Marettes.

But’s it’s not quite that easy…

There are a variety of types and sizes, and equipping yourself with the correct ones can lead to a lot of guess-work.

But don’t fret!

If you don’t have much experience working with wire nuts, you can use a wire nut size chart.

All you have to do is review both the size (or gauge) and number of cables you are working on and then cross-reference these to the correct wire nut sizes.

Accessing a wire nut size chart is one thing, but using the right nut for the job is crucial.

In this article, we’ll tell you exactly how to read these wire nut sizes charts, how to properly connect them, and answer any other related questions.

Overview of Wire Nut Sizes and Charts

When it comes to wire nuts, you need to know two things—the wire nut color code and wire nut sizes.

Understanding this is super easy:

Each of the colors, namely gray, blue, orange, yellow, and red, and the different sizes are intended to handle different amounts of gauge sizes and wire types.

#1. The Wire Nut Colors

The Gray Wire Nut

The gray wire nut can hold up to two 22AWG stranded wires or two solid 16AWG wires.

The gray nut is usually intended for fine-stranded wire applications.

The Blue Wire Nut

The blue one is slightly bigger than the gray wire nut.

The blue wire nut capacity can hold up to three 16 AWG solid wires.

This is the preferred wire of choice for ballast wire connections and is considered the largest wire nut.

The Orange Wire Nut

On the other hand, this bright wire nut is best if you need to connect at least one #18 and one #20 wire size.

It can hold up to 4 #16 and 1 #20 AWG wires. Usually, orange wire nuts are used to connect fans and lights to switch wires.

The Yellow Wire Nut

The yellow wire nut is your best choice if you need to connect four #14 and one #18 wire.

You can use these wire nuts for copper-to-copper, aluminum-to-aluminum, and copper-to-aluminum connections.

The Red Wire Nut

The last among the wire nut colors is red. The red wire nut capacity can accommodate up to 2 #10 and 2 #12.

If you need to get three #10 wires together, this is the wire nut of choice.

Like its yellow-colored counterpart, you can also use the red wire nut for copper-to-copper, aluminum-to-aluminum, and copper-to-aluminum connections.

#2. The Wire Nut Sizes

Since wire connections come in different sizes, the wire connectors are also designed to accommodate these different wire sizes.

A wrong wire nut size—either too big or too small for the number of wires you’ll connect—can lead to a weak connection.

What’s worse?

It can even cause a fire. And you can’t have that!

#3. The Wire Gauge

The wires are the ones that you will connect within or inside the wire nuts. This also refers to the thickness of the wire and is the one to identify the current that a wire can handle.

Your wire gauges can be the electrical and mechanical aspects of the current.

Today, two systems measure the gauge—the American Wire Gauge or AWG and the Standard Wire Gauge or SWG.

How to Use a Wire Nut Size Chart

Connecting wires is simple but fundamental electric work, and you need the right wire nut size.

For example, to install a ceiling light fixture, you’ll primarily work on three unscrewed wires in black, copper, and white.

A red wire connector usually (but not always) holds them in place.

Installation involves connecting three wires from the light fixture to the three wires coming out from your ceiling that connect to your primary power source.

These three cables are usually #14 AWG cables with a diameter of 1.628 mm.

The yellow wire nut size is the best wire nut that can provide a perfect fit.

You may wonder why:

It is not too tight that you can’t twist the wires together and not too loose that the wires come off easily.

The yellow wire nut capacity has a minimum of 2 #18 and a maximum of 4 #14 and 1 #18. You can use it for wires with a gauge of #18 to #12.

You may also consider using a wire nut on a breaker panel.

Is it even allowed?

Yes, as per the National Electric Code or (NEC), you can use wire nuts in your breaker panel!

Charts

The Wire Gauges

Before determining what color and size of wire nut to use, you must ensure that the total number of all the conductors in your wiring space is at most 40% of your cross-section.

Also, the overall conductors, splices, and/or taps installed on that specific cross-section should be less than 75% of the space.

Once you have checked these two parameters, you can check the wire gauge to pick the most appropriate wire nut to use.

In a breaker panel, orange and yellow are primarily used.

Here is another example.

You come across a package of blue wire nuts at Home Depot, and it is labeled four #10.

This means that in a single blue wire nut, you can twist and connect a maximum of 4 wires with a gauge size of #10 or an equivalent diameter of 2.588 mm, as shown in the table above.

You can’t exceed the capacity of wires, as this may cause an electrical malfunction in your system.

Wire Nut Size Chart with Minimum and Maximum AWG

Wire Nut Size Calculator

Frequently Asked Questions

#1. Does the Wire Nut Size Matter?

Yes, the size of the wire nut matters, and it makes a lot of difference in the reliability and safety of your wires.

Choosing an ill-fitting wire nut leads to loose or slack wire connectors and intermittent power problems. It may even lead to a fire.

To avoid this problem, select the right-sized wire nut based on the chart or your wire nut manufacturer’s recommendation.

It is also important to install the correct-sized wire nuts, and this video can serve as a refresher for you:

#2. Do You Need to Twist Wires Before the Wire Nut?

Today, most new wire connectors are already pre-twisted. Some don’t even need you to twist the wires.

But for a better mechanical joint, it is still best to twist the wires before setting in the wire nut.

This additional step can prevent the wires from prematurely being dislodged from your wire connectors.

Twisting the wires is especially recommended if you have multiple wire gauges or combined stranded and solid wires within just one connector.

#3. How Many Wires Can You Put in a Wire Nut?

The number of wires for a particular wire nut depends on its capacity. You must check the wire combinations for a particular wire nut color.

There is usually a standard wire combination for each color-coded wire nut.

However, check the enclosed wire nut size chart that the manufacturer sends with the product.

This still pays off, as there might be some slight deviations. Although, for most wire nuts, three wires are the safest combination for one wire nut.

Wire nuts play a critical part in electronics, but they can only serve their purpose effectively when you choose the right size and color.

You can have a better and well-organized electrical cabling system with the right wire nut choices.

You can also be confident that the connections within the wire nut are all safely assembled.

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